Table of Contents
List of Examples
/dev/sda
(MBR)/dev/sda
(UEFI)/dev/sda
emacs.nix
)configuration.nix
~/.config/nixpkgs/config.nix
mkEnableOption
usagemkPackageOption
usagemkPackageOption
with explicit default and examplemkPackageOption
with additional description textservices.xserver.displayManager.enable
in the gdm
moduleservices.xserver.displayManager.enable
in the sddm
moduletypes.anything
settings
optionsettings
attributeThis manual describes how to install, use and extend NixOS, a Linux distribution based on the purely functional package management system Nix, that is composed using modules and packages defined in the Nixpkgs project.
Additional information regarding the Nix package manager and the Nixpkgs project can be found in respectively the Nix manual and the Nixpkgs manual.
If you encounter problems, please report them on the Discourse
, the Matrix room, or on the #nixos
channel on Libera.Chat. Alternatively, consider contributing to this manual. Bugs should be reported in NixOS’ GitHub issue tracker.
Commands prefixed with #
have to be run as root, either requiring to login as root user or temporarily switching to it using sudo
for example.
This section describes how to obtain, install, and configure NixOS for first-time use.
NixOS ISO images can be downloaded from the NixOS download page. Follow the instructions in the section called “Booting from a USB flash drive” to create a bootable USB flash drive.
If you have a very old system that can’t boot from USB, you can burn the image to an empty CD. NixOS might not work very well on such systems.
As an alternative to installing NixOS yourself, you can get a running NixOS system through several other means:
Using virtual appliances in Open Virtualization Format (OVF) that can be imported into VirtualBox. These are available from the NixOS download page.
Using AMIs for Amazon’s EC2. To find one for your region, please refer to the download page.
Using NixOps, the NixOS-based cloud deployment tool, which allows you to provision VirtualBox and EC2 NixOS instances from declarative specifications. Check out the NixOps homepage for details.
Table of Contents
To begin the installation, you have to boot your computer from the install drive.
Plug in the install drive. Then turn on or restart your computer.
Open the boot menu by pressing the appropriate key, which is usually shown on the display on early boot. Select the USB flash drive (the option usually contains the word “USB”). If you choose the incorrect drive, your computer will likely continue to boot as normal. In that case restart your computer and pick a different drive.
The key to open the boot menu is different across computer brands and even models. It can be F12, but also F1, F9, F10, Enter, Del, Esc or another function key. If you are unsure and don’t see it on the early boot screen, you can search online for your computers brand, model followed by “boot from usb”. The computer might not even have that feature, so you have to go into the BIOS/UEFI settings to change the boot order. Again, search online for details about your specific computer model.
For Apple computers with Intel processors press and hold the ⌥ (Option or Alt) key until you see the boot menu. On Apple silicon press and hold the power button.
If your computer supports both BIOS and UEFI boot, choose the UEFI option.
If you use a CD for the installation, the computer will probably boot from it automatically. If not, choose the option containing the word “CD” from the boot menu.
Shortly after selecting the appropriate boot drive, you should be presented with a menu with different installer options. Leave the default and wait (or press Enter to speed up).
The graphical images will start their corresponding desktop environment and the graphical installer, which can take some time. The minimal images will boot to a command line. You have to follow the instructions in the section called “Manual Installation” there.
The graphical installer is recommended for desktop users and will guide you through the installation.
In the “Welcome” screen, you can select the language of the Installer and the installed system.
Leaving the language as “American English” will make it easier to search for error messages in a search engine or to report an issue.
Next you should choose your location to have the timezone set correctly. You can actually click on the map!
The installer will use an online service to guess your location based on your public IP address.
Then you can select the keyboard layout. The default keyboard model should work well with most desktop keyboards. If you have a special keyboard or notebook, your model might be in the list. Select the language you are most comfortable typing in.
On the “Users” screen, you have to type in your display name, login name and password. You can also enable an option to automatically login to the desktop.
Then you have the option to choose a desktop environment. If you want to create a custom setup with a window manager, you can select “No desktop”.
If you don’t have a favorite desktop and don’t know which one to choose, you can stick to either GNOME or Plasma. They have a quite different design, so you should choose whichever you like better. They are both popular choices and well tested on NixOS.
You have the option to allow unfree software in the next screen.
The easiest option in the “Partitioning” screen is “Erase disk”, which will delete all data from the selected disk and install the system on it. Also select “Swap (with Hibernation)” in the dropdown below it. You have the option to encrypt the whole disk with LUKS.
At the top left you see if the Installer was booted with BIOS or UEFI. If you know your system supports UEFI and it shows “BIOS”, reboot with the correct option.
Make sure you have selected the correct disk at the top and that no valuable data is still on the disk! It will be deleted when formatting the disk.
Check the choices you made in the “Summary” and click “Install”.
The installation takes about 15 minutes. The time varies based on the selected desktop environment, internet connection speed and disk write speed.
When the install is complete, remove the USB flash drive and reboot into your new system!
NixOS can be installed on BIOS or UEFI systems. The procedure for a UEFI installation is broadly the same as for a BIOS installation. The differences are mentioned in the following steps.
The NixOS manual is available by running nixos-help
in the command line
or from the application menu in the desktop environment.
To have access to the command line on the graphical images, open Terminal (GNOME) or Konsole (Plasma) from the application menu.
You are logged-in automatically as nixos
. The nixos
user account has
an empty password so you can use sudo
without a password:
$ sudo -i
You can use loadkeys
to switch to your preferred keyboard layout.
(We even provide neo2 via loadkeys de neo
!)
If the text is too small to be legible, try setfont ter-v32n
to
increase the font size.
To install over a serial port connect with 115200n8
(e.g.
picocom -b 115200 /dev/ttyUSB0
). When the bootloader lists boot
entries, select the serial console boot entry.
The boot process should have brought up networking (check ip a
). Networking is necessary for the installer, since it will
download lots of stuff (such as source tarballs or Nixpkgs channel
binaries). It’s best if you have a DHCP server on your network.
Otherwise configure networking manually using ifconfig
.
On the graphical installer, you can configure the network, wifi
included, through NetworkManager. Using the nmtui
program, you can do
so even in a non-graphical session. If you prefer to configure the
network manually, disable NetworkManager with
systemctl stop NetworkManager
.
On the minimal installer, NetworkManager is not available, so
configuration must be performed manually. To configure the wifi, first
start wpa_supplicant with sudo systemctl start wpa_supplicant
, then
run wpa_cli
. For most home networks, you need to type in the following
commands:
> add_network
0
> set_network 0 ssid "myhomenetwork"
OK
> set_network 0 psk "mypassword"
OK
> set_network 0 key_mgmt WPA-PSK
OK
> enable_network 0
OK
For enterprise networks, for example eduroam, instead do:
> add_network
0
> set_network 0 ssid "eduroam"
OK
> set_network 0 identity "myname@example.com"
OK
> set_network 0 password "mypassword"
OK
> set_network 0 key_mgmt WPA-EAP
OK
> enable_network 0
OK
When successfully connected, you should see a line such as this one
<3>CTRL-EVENT-CONNECTED - Connection to 32:85:ab:ef:24:5c completed [id=0 id_str=]
you can now leave wpa_cli
by typing quit
.
If you would like to continue the installation from a different machine
you can use activated SSH daemon. You need to copy your ssh key to
either /home/nixos/.ssh/authorized_keys
or
/root/.ssh/authorized_keys
(Tip: For installers with a modifiable
filesystem such as the sd-card installer image a key can be manually
placed by mounting the image on a different machine). Alternatively you
must set a password for either root
or nixos
with passwd
to be
able to login.
The NixOS installer doesn’t do any partitioning or formatting, so you need to do that yourself.
The NixOS installer ships with multiple partitioning tools. The examples
below use parted
, but also provides fdisk
, gdisk
, cfdisk
, and
cgdisk
.
The recommended partition scheme differs depending if the computer uses Legacy Boot or UEFI.
Here’s an example partition scheme for UEFI, using /dev/sda
as the
device.
You can safely ignore parted
’s informational message about needing to
update /etc/fstab.
Create a GPT partition table.
# parted /dev/sda -- mklabel gpt
Add the root partition. This will fill the disk except for the end part, where the swap will live, and the space left in front (512MiB) which will be used by the boot partition.
# parted /dev/sda -- mkpart root ext4 512MB -8GB
Next, add a swap partition. The size required will vary according to needs, here a 8GB one is created.
# parted /dev/sda -- mkpart swap linux-swap -8GB 100%
The swap partition size rules are no different than for other Linux distributions.
Finally, the boot partition. NixOS by default uses the ESP (EFI system partition) as its /boot partition. It uses the initially reserved 512MiB at the start of the disk.
# parted /dev/sda -- mkpart ESP fat32 1MB 512MB
# parted /dev/sda -- set 3 esp on
In case you decided to not create a swap partition, replace 3
by 2
. To be sure of the id number of ESP, run parted --list
.
Once complete, you can follow with the section called “Formatting”.
Here’s an example partition scheme for Legacy Boot, using /dev/sda
as
the device.
You can safely ignore parted
’s informational message about needing to
update /etc/fstab.
Create a MBR partition table.
# parted /dev/sda -- mklabel msdos
Add the root partition. This will fill the the disk except for the end part, where the swap will live.
# parted /dev/sda -- mkpart primary 1MB -8GB
Set the root partition’s boot flag to on. This allows the disk to be booted from.
# parted /dev/sda -- set 1 boot on
Finally, add a swap partition. The size required will vary according to needs, here a 8GB one is created.
# parted /dev/sda -- mkpart primary linux-swap -8GB 100%
The swap partition size rules are no different than for other Linux distributions.
Once complete, you can follow with the section called “Formatting”.
Use the following commands:
For initialising Ext4 partitions: mkfs.ext4
. It is recommended
that you assign a unique symbolic label to the file system using the
option -L label
, since this makes the file system configuration
independent from device changes. For example:
# mkfs.ext4 -L nixos /dev/sda1
For creating swap partitions: mkswap
. Again it’s recommended to
assign a label to the swap partition: -L label
. For example:
# mkswap -L swap /dev/sda2
UEFI systems
For creating boot partitions: mkfs.fat
. Again it’s recommended
to assign a label to the boot partition: -n label
. For
example:
# mkfs.fat -F 32 -n boot /dev/sda3
For creating LVM volumes, the LVM commands, e.g., pvcreate
,
vgcreate
, and lvcreate
.
For creating software RAID devices, use mdadm
.
Mount the target file system on which NixOS should be installed on
/mnt
, e.g.
# mount /dev/disk/by-label/nixos /mnt
UEFI systems
Mount the boot file system on /mnt/boot
, e.g.
# mkdir -p /mnt/boot
# mount -o umask=077 /dev/disk/by-label/boot /mnt/boot
If your machine has a limited amount of memory, you may want to
activate swap devices now (swapon device
).
The installer (or rather, the build actions that it
may spawn) may need quite a bit of RAM, depending on your
configuration.
# swapon /dev/sda2
You now need to create a file /mnt/etc/nixos/configuration.nix
that specifies the intended configuration of the system. This is
because NixOS has a declarative configuration model: you create or
edit a description of the desired configuration of your system, and
then NixOS takes care of making it happen. The syntax of the NixOS
configuration file is described in Configuration Syntax,
while a list of available configuration options appears in
Appendix A. A minimal example is shown in
Example: NixOS Configuration.
The command nixos-generate-config
can generate an initial
configuration file for you:
# nixos-generate-config --root /mnt
You should then edit /mnt/etc/nixos/configuration.nix
to suit your
needs:
# nano /mnt/etc/nixos/configuration.nix
If you’re using the graphical ISO image, other editors may be
available (such as vim
). If you have network access, you can also
install other editors – for instance, you can install Emacs by
running nix-env -f '<nixpkgs>' -iA emacs
.
You must set the option boot.loader.grub.device
to
specify on which disk the GRUB boot loader is to be installed.
Without it, NixOS cannot boot.
If there are other operating systems running on the machine before
installing NixOS, the boot.loader.grub.useOSProber
option can be set to true
to automatically add them to the grub
menu.
You must select a boot-loader, either systemd-boot or GRUB. The recommended
option is systemd-boot: set the option boot.loader.systemd-boot.enable
to true
. nixos-generate-config
should do this automatically
for new configurations when booted in UEFI mode.
You may want to look at the options starting with
boot.loader.efi
and
boot.loader.systemd-boot
as well.
If you want to use GRUB, set boot.loader.grub.device
to nodev
and
boot.loader.grub.efiSupport
to true
.
With systemd-boot, you should not need any special configuration to detect
other installed systems. With GRUB, set boot.loader.grub.useOSProber
to true
, but this will only detect windows partitions, not other Linux
distributions. If you dual boot another Linux distribution, use systemd-boot
instead.
If you need to configure networking for your machine the
configuration options are described in Networking. In
particular, while wifi is supported on the installation image, it is
not enabled by default in the configuration generated by
nixos-generate-config
.
Another critical option is fileSystems
, specifying the file
systems that need to be mounted by NixOS. However, you typically
don’t need to set it yourself, because nixos-generate-config
sets
it automatically in /mnt/etc/nixos/hardware-configuration.nix
from
your currently mounted file systems. (The configuration file
hardware-configuration.nix
is included from configuration.nix
and will be overwritten by future invocations of
nixos-generate-config
; thus, you generally should not modify it.)
Additionally, you may want to look at Hardware configuration for
known-hardware at this
point or after installation.
Depending on your hardware configuration or type of file system, you
may need to set the option boot.initrd.kernelModules
to include
the kernel modules that are necessary for mounting the root file
system, otherwise the installed system will not be able to boot. (If
this happens, boot from the installation media again, mount the
target file system on /mnt
, fix /mnt/etc/nixos/configuration.nix
and rerun nixos-install
.) In most cases, nixos-generate-config
will figure out the required modules.
Do the installation:
# nixos-install
This will install your system based on the configuration you
provided. If anything fails due to a configuration problem or any
other issue (such as a network outage while downloading binaries
from the NixOS binary cache), you can re-run nixos-install
after
fixing your configuration.nix
.
As the last step, nixos-install
will ask you to set the password
for the root
user, e.g.
setting root password...
New password: ***
Retype new password: ***
For unattended installations, it is possible to use
nixos-install --no-root-passwd
in order to disable the password
prompt entirely.
If everything went well:
# reboot
You should now be able to boot into the installed NixOS. The GRUB boot menu shows a list of available configurations (initially just one). Every time you change the NixOS configuration (see Changing Configuration), a new item is added to the menu. This allows you to easily roll back to a previous configuration if something goes wrong.
You should log in and change the root
password with passwd
.
You’ll probably want to create some user accounts as well, which can
be done with useradd
:
$ useradd -c 'Eelco Dolstra' -m eelco
$ passwd eelco
You may also want to install some software. This will be covered in Package Management.
To summarise, Example: Commands for Installing NixOS on /dev/sda
shows a typical sequence of commands for installing NixOS on an empty hard
drive (here /dev/sda
). Example: NixOS Configuration shows a
corresponding configuration Nix expression.
/dev/sda
(MBR)# parted /dev/sda -- mklabel msdos
# parted /dev/sda -- mkpart primary 1MB -8GB
# parted /dev/sda -- mkpart primary linux-swap -8GB 100%
/dev/sda
(UEFI)# parted /dev/sda -- mklabel gpt
# parted /dev/sda -- mkpart root ext4 512MB -8GB
# parted /dev/sda -- mkpart swap linux-swap -8GB 100%
# parted /dev/sda -- mkpart ESP fat32 1MB 512MB
# parted /dev/sda -- set 3 esp on
/dev/sda
With a partitioned disk.
# mkfs.ext4 -L nixos /dev/sda1
# mkswap -L swap /dev/sda2
# swapon /dev/sda2
# mkfs.fat -F 32 -n boot /dev/sda3 # (for UEFI systems only)
# mount /dev/disk/by-label/nixos /mnt
# mkdir -p /mnt/boot # (for UEFI systems only)
# mount -o umask=077 /dev/disk/by-label/boot /mnt/boot # (for UEFI systems only)
# nixos-generate-config --root /mnt
# nano /mnt/etc/nixos/configuration.nix
# nixos-install
# reboot
{ config, pkgs, ... }: {
imports = [
# Include the results of the hardware scan.
./hardware-configuration.nix
];
boot.loader.grub.device = "/dev/sda"; # (for BIOS systems only)
boot.loader.systemd-boot.enable = true; # (for UEFI systems only)
# Note: setting fileSystems is generally not
# necessary, since nixos-generate-config figures them out
# automatically in hardware-configuration.nix.
#fileSystems."/".device = "/dev/disk/by-label/nixos";
# Enable the OpenSSH server.
services.sshd.enable = true;
}
The image has to be written verbatim to the USB flash drive for it to be bootable on UEFI and BIOS systems. Here are the recommended tools to do that.
Etcher is a popular and user-friendly tool. It works on Linux, Windows and macOS.
Download it from balena.io, start the program, select the downloaded NixOS ISO, then select the USB flash drive and flash it.
Etcher reports errors and usage statistics by default, which can be disabled in the settings.
An alternative is USBImager, which is very simple and does not connect to the internet. Download the version with write-only (wo) interface for your system. Start the program, select the image, select the USB flash drive and click “Write”.
Plug in the USB flash drive.
Find the corresponding device with lsblk
. You can distinguish them by
their size.
Make sure all partitions on the device are properly unmounted. Replace sdX
with your device (e.g. sdb
).
sudo umount /dev/sdX*
Then use the dd
utility to write the image to the USB flash drive.
sudo dd bs=4M conv=fsync oflag=direct status=progress if=<path-to-image> of=/dev/sdX
Plug in the USB flash drive.
Find the corresponding device with diskutil list
. You can distinguish them
by their size.
Make sure all partitions on the device are properly unmounted. Replace diskX
with your device (e.g. disk1
).
diskutil unmountDisk diskX
Then use the dd
utility to write the image to the USB flash drive.
sudo dd if=<path-to-image> of=/dev/rdiskX bs=4m
After dd
completes, a GUI dialog “The disk
you inserted was not readable by this computer” will pop up, which can
be ignored.
Using the ‘raw’ rdiskX
device instead of diskX
with dd completes in
minutes instead of hours.
Eject the disk when it is finished.
diskutil eject /dev/diskX
Advanced users may wish to install NixOS using an existing PXE or iPXE setup.
These instructions assume that you have an existing PXE or iPXE infrastructure and want to add the NixOS installer as another option. To build the necessary files from your current version of nixpkgs, you can run:
nix-build -A netboot.x86_64-linux '<nixpkgs/nixos/release.nix>'
This will create a result
directory containing: * bzImage
– the
Linux kernel * initrd
– the initrd file * netboot.ipxe
– an
example ipxe script demonstrating the appropriate kernel command line
arguments for this image
If you’re using plain PXE, configure your boot loader to use the
bzImage
and initrd
files and have it provide the same kernel command
line arguments found in netboot.ipxe
.
If you’re using iPXE, depending on how your HTTP/FTP/etc. server is
configured you may be able to use netboot.ipxe
unmodified, or you may
need to update the paths to the files to match your server’s directory
layout.
In the future we may begin making these files available as build products from hydra at which point we will update this documentation with instructions on how to obtain them either for placing on a dedicated TFTP server or to boot them directly over the internet.
In some cases, your system might already be booted into/preinstalled with another Linux distribution, and booting NixOS by attaching an installation image is quite a manual process.
This is particularly useful for (cloud) providers where you can’t boot a custom image, but get some Debian or Ubuntu installation.
In these cases, it might be easier to use kexec
to “jump into NixOS” from the
running system, which only assumes bash
and kexec
to be installed on the
machine.
Note that kexec may not work correctly on some hardware, as devices are not fully re-initialized in the process. In practice, this however is rarely the case.
To build the necessary files from your current version of nixpkgs, you can run:
nix-build -A kexec.x86_64-linux '<nixpkgs/nixos/release.nix>'
This will create a result
directory containing the following:
bzImage
(the Linux kernel)
initrd
(the initrd file)
kexec-boot
(a shellscript invoking kexec
)
These three files are meant to be copied over to the other already running Linux Distribution.
Note its symlinks pointing elsewhere, so cd
in, and use
scp * root@$destination
to copy it over, rather than rsync.
Once you finished copying, execute kexec-boot
on the destination, and after
some seconds, the machine should be booting into an (ephemeral) NixOS
installation medium.
In case you want to describe your own system closure to kexec into, instead of
the default installer image, you can build your own configuration.nix
:
{ modulesPath, ... }: {
imports = [
(modulesPath + "/installer/netboot/netboot-minimal.nix")
];
services.openssh.enable = true;
users.users.root.openssh.authorizedKeys.keys = [
"my-ssh-pubkey"
];
}
nix-build '<nixpkgs/nixos>' \
--arg configuration ./configuration.nix
--attr config.system.build.kexecTree
Make sure your configuration.nix
does still import netboot-minimal.nix
(or
netboot-base.nix
).
Installing NixOS into a VirtualBox guest is convenient for users who want to try NixOS without installing it on bare metal. If you want to use a pre-made VirtualBox appliance, it is available at the downloads page. If you want to set up a VirtualBox guest manually, follow these instructions:
Add a New Machine in VirtualBox with OS Type “Linux / Other Linux”
Base Memory Size: 768 MB or higher.
New Hard Disk of 8 GB or higher.
Mount the CD-ROM with the NixOS ISO (by clicking on CD/DVD-ROM)
Click on Settings / System / Processor and enable PAE/NX
Click on Settings / System / Acceleration and enable “VT-x/AMD-V” acceleration
Click on Settings / Display / Screen and select VMSVGA as Graphics Controller
Save the settings, start the virtual machine, and continue installation like normal
There are a few modifications you should make in configuration.nix. Enable booting:
{
boot.loader.grub.device = "/dev/sda";
}
Also remove the fsck that runs at startup. It will always fail to run,
stopping your boot until you press *
.
{
boot.initrd.checkJournalingFS = false;
}
Shared folders can be given a name and a path in the host system in the
VirtualBox settings (Machine / Settings / Shared Folders, then click on
the “Add” icon). Add the following to the
/etc/nixos/configuration.nix
to auto-mount them. If you do not add
"nofail"
, the system will not boot properly.
{ config, pkgs, ...} :
{
fileSystems."/virtualboxshare" = {
fsType = "vboxsf";
device = "nameofthesharedfolder";
options = [ "rw" "nofail" ];
};
}
The folder will be available directly under the root directory.
Because Nix (the package manager) & Nixpkgs (the Nix packages collection) can both be installed on any (most?) Linux distributions, they can be used to install NixOS in various creative ways. You can, for instance:
Install NixOS on another partition, from your existing Linux distribution (without the use of a USB or optical device!)
Install NixOS on the same partition (in place!), from your existing
non-NixOS Linux distribution using NIXOS_LUSTRATE
.
Install NixOS on your hard drive from the Live CD of any Linux distribution.
The first steps to all these are the same:
Install the Nix package manager:
Short version:
$ curl -L https://nixos.org/nix/install | sh
$ . $HOME/.nix-profile/etc/profile.d/nix.sh # …or open a fresh shell
More details in the Nix manual
Switch to the NixOS channel:
If you’ve just installed Nix on a non-NixOS distribution, you will
be on the nixpkgs
channel by default.
$ nix-channel --list
nixpkgs https://nixos.org/channels/nixpkgs-unstable
As that channel gets released without running the NixOS tests, it
will be safer to use the nixos-*
channels instead:
$ nix-channel --add https://nixos.org/channels/nixos-<version> nixpkgs
Where <version>
corresponds to the latest version available on channels.nixos.org.
You may want to throw in a nix-channel --update
for good measure.
Install the NixOS installation tools:
You’ll need nixos-generate-config
and nixos-install
, but this
also makes some man pages and nixos-enter
available, just in case
you want to chroot into your NixOS partition. NixOS installs these
by default, but you don’t have NixOS yet…
$ nix-env -f '<nixpkgs>' -iA nixos-install-tools
The following 5 steps are only for installing NixOS to another
partition. For installing NixOS in place using NIXOS_LUSTRATE
,
skip ahead.
Prepare your target partition:
At this point it is time to prepare your target partition. Please refer to the partitioning, file-system creation, and mounting steps of Installing NixOS
If you’re about to install NixOS in place using NIXOS_LUSTRATE
there is nothing to do for this step.
Generate your NixOS configuration:
$ sudo `which nixos-generate-config` --root /mnt
You’ll probably want to edit the configuration files. Refer to the
nixos-generate-config
step in Installing NixOS for more
information.
Consider setting up the NixOS bootloader to give you the ability to
boot on your existing Linux partition. For instance, if you’re
using GRUB and your existing distribution is running Ubuntu, you may
want to add something like this to your configuration.nix
:
{
boot.loader.grub.extraEntries = ''
menuentry "Ubuntu" {
search --set=ubuntu --fs-uuid 3cc3e652-0c1f-4800-8451-033754f68e6e
configfile "($ubuntu)/boot/grub/grub.cfg"
}
'';
}
(You can find the appropriate UUID for your partition in
/dev/disk/by-uuid
)
Create the nixbld
group and user on your original distribution:
$ sudo groupadd -g 30000 nixbld
$ sudo useradd -u 30000 -g nixbld -G nixbld nixbld
Download/build/install NixOS:
Once you complete this step, you might no longer be able to boot on existing systems without the help of a rescue USB drive or similar.
On some distributions there are separate PATHS for programs intended
only for root. In order for the installation to succeed, you might
have to use PATH="$PATH:/usr/sbin:/sbin"
in the following command.
$ sudo PATH="$PATH" NIX_PATH="$NIX_PATH" `which nixos-install` --root /mnt
Again, please refer to the nixos-install
step in
Installing NixOS for more information.
That should be it for installation to another partition!
Optionally, you may want to clean up your non-NixOS distribution:
$ sudo userdel nixbld
$ sudo groupdel nixbld
If you do not wish to keep the Nix package manager installed either,
run something like sudo rm -rv ~/.nix-* /nix
and remove the line
that the Nix installer added to your ~/.profile
.
The following steps are only for installing NixOS in place using
NIXOS_LUSTRATE
:
Generate your NixOS configuration:
$ sudo `which nixos-generate-config`
Note that this will place the generated configuration files in
/etc/nixos
. You’ll probably want to edit the configuration files.
Refer to the nixos-generate-config
step in
Installing NixOS for more information.
You’ll likely want to set a root password for your first boot using
the configuration files because you won’t have a chance to enter a
password until after you reboot. You can initialize the root password
to an empty one with this line: (and of course don’t forget to set
one once you’ve rebooted or to lock the account with
sudo passwd -l root
if you use sudo
)
{
users.users.root.initialHashedPassword = "";
}
Build the NixOS closure and install it in the system
profile:
$ nix-env -p /nix/var/nix/profiles/system -f '<nixpkgs/nixos>' -I nixos-config=/etc/nixos/configuration.nix -iA system
Change ownership of the /nix
tree to root (since your Nix install
was probably single user):
$ sudo chown -R 0:0 /nix
Set up the /etc/NIXOS
and /etc/NIXOS_LUSTRATE
files:
/etc/NIXOS
officializes that this is now a NixOS partition (the
bootup scripts require its presence).
/etc/NIXOS_LUSTRATE
tells the NixOS bootup scripts to move
everything that’s in the root partition to /old-root
. This will
move your existing distribution out of the way in the very early
stages of the NixOS bootup. There are exceptions (we do need to keep
NixOS there after all), so the NixOS lustrate process will not
touch:
The /nix
directory
The /boot
directory
Any file or directory listed in /etc/NIXOS_LUSTRATE
(one per
line)
Support for NIXOS_LUSTRATE
was added in NixOS 16.09. The act of
“lustrating” refers to the wiping of the existing distribution.
Creating /etc/NIXOS_LUSTRATE
can also be used on NixOS to remove
all mutable files from your root partition (anything that’s not in
/nix
or /boot
gets “lustrated” on the next boot.
lustrate /ˈlʌstreɪt/ verb.
purify by expiatory sacrifice, ceremonial washing, or some other ritual action.
Let’s create the files:
$ sudo touch /etc/NIXOS
$ sudo touch /etc/NIXOS_LUSTRATE
Let’s also make sure the NixOS configuration files are kept once we reboot on NixOS:
$ echo etc/nixos | sudo tee -a /etc/NIXOS_LUSTRATE
Finally, move the /boot
directory of your current distribution out
of the way (the lustrate process will take care of the rest once you
reboot, but this one must be moved out now because NixOS needs to
install its own boot files:
Once you complete this step, your current distribution will no longer be bootable! If you didn’t get all the NixOS configuration right, especially those settings pertaining to boot loading and root partition, NixOS may not be bootable either. Have a USB rescue device ready in case this happens.
$ sudo mv -v /boot /boot.bak &&
sudo /nix/var/nix/profiles/system/bin/switch-to-configuration boot
Cross your fingers, reboot, hopefully you should get a NixOS prompt!
If for some reason you want to revert to the old distribution, you’ll need to boot on a USB rescue disk and do something along these lines:
# mkdir root
# mount /dev/sdaX root
# mkdir root/nixos-root
# mv -v root/* root/nixos-root/
# mv -v root/nixos-root/old-root/* root/
# mv -v root/boot.bak root/boot # We had renamed this by hand earlier
# umount root
# reboot
This may work as is or you might also need to reinstall the boot loader.
And of course, if you’re happy with NixOS and no longer need the old distribution:
sudo rm -rf /old-root
It’s also worth noting that this whole process can be automated. This is especially useful for Cloud VMs, where provider do not provide NixOS. For instance, nixos-infect uses the lustrate process to convert Digital Ocean droplets to NixOS from other distributions automatically.
To install NixOS behind a proxy, do the following before running
nixos-install
.
Update proxy configuration in /mnt/etc/nixos/configuration.nix
to
keep the internet accessible after reboot.
{
networking.proxy.default = "http://user:password@proxy:port/";
networking.proxy.noProxy = "127.0.0.1,localhost,internal.domain";
}
Setup the proxy environment variables in the shell where you are
running nixos-install
.
# proxy_url="http://user:password@proxy:port/"
# export http_proxy="$proxy_url"
# export HTTP_PROXY="$proxy_url"
# export https_proxy="$proxy_url"
# export HTTPS_PROXY="$proxy_url"
If you are switching networks with different proxy configurations, use
the specialisation
option in configuration.nix
to switch proxies at
runtime. Refer to Appendix A for more information.
The file /etc/nixos/configuration.nix
contains the current
configuration of your machine. Whenever you’ve changed
something in that file, you should do
# nixos-rebuild switch
to build the new configuration, make it the default configuration for booting, and try to realise the configuration in the running system (e.g., by restarting system services).
This command doesn’t start/stop user services
automatically. nixos-rebuild
only runs a daemon-reload
for each user with running
user services.
These commands must be executed as root, so you should either run them
from a root shell or by prefixing them with sudo -i
.
You can also do
# nixos-rebuild test
to build the configuration and switch the running system to it, but without making it the boot default. So if (say) the configuration locks up your machine, you can just reboot to get back to a working configuration.
There is also
# nixos-rebuild boot
to build the configuration and make it the boot default, but not switch to it now (so it will only take effect after the next reboot).
You can make your configuration show up in a different submenu of the GRUB 2 boot screen by giving it a different profile name, e.g.
# nixos-rebuild switch -p test
which causes the new configuration (and previous ones created using
-p test
) to show up in the GRUB submenu “NixOS - Profile ‘test’”.
This can be useful to separate test configurations from “stable”
configurations.
A repl, or read-eval-print loop, is also available. You can inspect your configuration and use the Nix language with
# nixos-rebuild repl
Your configuration is loaded into the config
variable. Use tab for autocompletion, use the :r
command to reload the configuration files. See :?
or nix repl
in the Nix manual to learn more.
Finally, you can do
$ nixos-rebuild build
to build the configuration but nothing more. This is useful to see whether everything compiles cleanly.
If you have a machine that supports hardware virtualisation, you can also test the new configuration in a sandbox by building and running a QEMU virtual machine that contains the desired configuration. Just do
$ nixos-rebuild build-vm
$ ./result/bin/run-*-vm
The VM does not have any data from your host system, so your existing
user accounts and home directories will not be available unless you have
set mutableUsers = false
. Another way is to temporarily add the
following to your configuration:
{
users.users.your-user.initialHashedPassword = "test";
}
Important: delete the $hostname.qcow2 file if you have started the virtual machine at least once without the right users, otherwise the changes will not get picked up. You can forward ports on the host to the guest. For instance, the following will forward host port 2222 to guest port 22 (SSH):
$ QEMU_NET_OPTS="hostfwd=tcp:127.0.0.1:2222-:22" ./result/bin/run-*-vm
allowing you to log in via SSH (assuming you have set the appropriate passwords or SSH authorized keys):
$ ssh -p 2222 localhost
Such port forwardings connect via the VM’s virtual network interface.
Thus they cannot connect to ports that are only bound to the VM’s
loopback interface (127.0.0.1
), and the VM’s NixOS firewall
must be configured to allow these connections.
Table of Contents
The best way to keep your NixOS installation up to date is to use one of the NixOS channels. A channel is a Nix mechanism for distributing Nix expressions and associated binaries. The NixOS channels are updated automatically from NixOS’s Git repository after certain tests have passed and all packages have been built. These channels are:
Stable channels, such as nixos-23.11
.
These only get conservative bug fixes and package upgrades. For
instance, a channel update may cause the Linux kernel on your system
to be upgraded from 4.19.34 to 4.19.38 (a minor bug fix), but not
from 4.19.x to 4.20.x (a major change that has the potential to break things).
Stable channels are generally maintained until the next stable
branch is created.
The unstable channel, nixos-unstable
.
This corresponds to NixOS’s main development branch, and may thus see
radical changes between channel updates. It’s not recommended for
production systems.
Small channels, such as nixos-23.11-small
or nixos-unstable-small
.
These are identical to the stable and unstable channels described above,
except that they contain fewer binary packages. This means they get updated
faster than the regular channels (for instance, when a critical security patch
is committed to NixOS’s source tree), but may require more packages to be
built from source than usual. They’re mostly intended for server environments
and as such contain few GUI applications.
To see what channels are available, go to https://channels.nixos.org. (Note that the URIs of the various channels redirect to a directory that contains the channel’s latest version and includes ISO images and VirtualBox appliances.) Please note that during the release process, channels that are not yet released will be present here as well. See the Getting NixOS page https://nixos.org/download/ to find the newest supported stable release.
When you first install NixOS, you’re automatically subscribed to the
NixOS channel that corresponds to your installation source. For
instance, if you installed from a 23.11 ISO, you will be subscribed to
the nixos-23.11
channel. To see which NixOS channel you’re subscribed
to, run the following as root:
# nix-channel --list | grep nixos
nixos https://channels.nixos.org/nixos-unstable
To switch to a different NixOS channel, do
# nix-channel --add https://channels.nixos.org/channel-name nixos
(Be sure to include the nixos
parameter at the end.) For instance, to
use the NixOS 23.11 stable channel:
# nix-channel --add https://channels.nixos.org/nixos-23.11 nixos
If you have a server, you may want to use the “small” channel instead:
# nix-channel --add https://channels.nixos.org/nixos-23.11-small nixos
And if you want to live on the bleeding edge:
# nix-channel --add https://channels.nixos.org/nixos-unstable nixos
You can then upgrade NixOS to the latest version in your chosen channel by running
# nixos-rebuild switch --upgrade
which is equivalent to the more verbose nix-channel --update nixos; nixos-rebuild switch
.
Channels are set per user. This means that running nix-channel --add
as a non root user (or without sudo) will not affect
configuration in /etc/nixos/configuration.nix
It is generally safe to switch back and forth between channels. The only exception is that a newer NixOS may also have a newer Nix version, which may involve an upgrade of Nix’s database schema. This cannot be undone easily, so in that case you will not be able to go back to your original channel.
You can keep a NixOS system up-to-date automatically by adding the
following to configuration.nix
:
{
system.autoUpgrade.enable = true;
system.autoUpgrade.allowReboot = true;
}
This enables a periodically executed systemd service named
nixos-upgrade.service
. If the allowReboot
option is false
, it runs
nixos-rebuild switch --upgrade
to upgrade NixOS to the latest version
in the current channel. (To see when the service runs, see systemctl list-timers
.)
If allowReboot
is true
, then the system will automatically reboot if
the new generation contains a different kernel, initrd or kernel
modules. You can also specify a channel explicitly, e.g.
{
system.autoUpgrade.channel = "https://channels.nixos.org/nixos-23.11";
}
Table of Contents
Default live installer configurations are available inside nixos/modules/installer/cd-dvd
.
For building other system images, nixos-generators is a good place to start looking at.
You have two options:
Use any of those default configurations as is
Combine them with (any of) your host config(s)
System images, such as the live installer ones, know how to enforce configuration settings on which they immediately depend in order to work correctly.
However, if you are confident, you can opt to override those
enforced values with mkForce
.
To build an ISO image for the channel nixos-unstable
:
$ git clone https://github.com/NixOS/nixpkgs.git
$ cd nixpkgs/nixos
$ git switch nixos-unstable
$ nix-build -A config.system.build.isoImage -I nixos-config=modules/installer/cd-dvd/installation-cd-minimal.nix default.nix
To check the content of an ISO image, mount it like so:
# mount -o loop -t iso9660 ./result/iso/cd.iso /mnt/iso
If you need additional (non-distributable) drivers or firmware in the installer, you might want to extend these configurations.
For example, to build the GNOME graphical installer ISO, but with support for
certain WiFi adapters present in some MacBooks, you can create the following
file at modules/installer/cd-dvd/installation-cd-graphical-gnome-macbook.nix
:
{ config, ... }:
{
imports = [ ./installation-cd-graphical-gnome.nix ];
boot.initrd.kernelModules = [ "wl" ];
boot.kernelModules = [ "kvm-intel" "wl" ];
boot.extraModulePackages = [ config.boot.kernelPackages.broadcom_sta ];
}
Then build it like in the example above:
$ git clone https://github.com/NixOS/nixpkgs.git
$ cd nixpkgs/nixos
$ export NIXPKGS_ALLOW_UNFREE=1
$ nix-build -A config.system.build.isoImage -I nixos-config=modules/installer/cd-dvd/installation-cd-graphical-gnome-macbook.nix default.nix
The config value enforcement is implemented via mkImageMediaOverride = mkOverride 60;
and therefore primes over simple value assignments, but also yields to mkForce
.
This property allows image designers to implement in semantically correct ways those configuration values upon which the correct functioning of the image depends.
For example, the iso base image overrides those file systems which it needs at a minimum for correct functioning, while the installer base image overrides the entire file system layout because there can’t be any other guarantees on a live medium than those given by the live medium itself. The latter is especially true before formatting the target block device(s). On the other hand, the netboot iso only overrides its minimum dependencies since netboot images are always made-to-target.
systemd-repart
Table of Contents
You can build disk images in NixOS with the image.repart
option provided by
the module image/repart.nix. This module uses systemd-repart
to build the
images and exposes it’s entire interface via the repartConfig
option.
An example of how to build an image:
{ config, modulesPath, ... }: {
imports = [ "${modulesPath}/image/repart.nix" ];
image.repart = {
name = "image";
partitions = {
"esp" = {
contents = {
# ...
};
repartConfig = {
Type = "esp";
# ...
};
};
"root" = {
storePaths = [ config.system.build.toplevel ];
repartConfig = {
Type = "root";
Label = "nixos";
# ...
};
};
};
};
}
You can define a partition that only contains the Nix store and then mount it
under /nix/store
. Because the /nix/store
part of the paths is already
determined by the mount point, you have to set stripNixStorePrefix = true;
so
that the prefix is stripped from the paths before copying them into the image.
{
fileSystems."/nix/store".device = "/dev/disk/by-partlabel/nix-store";
image.repart.partitions = {
"store" = {
storePaths = [ config.system.build.toplevel ];
stripNixStorePrefix = true;
repartConfig = {
Type = "linux-generic";
Label = "nix-store";
# ...
};
};
};
}
The image/repart.nix
module can also be used to build self-contained software
appliances.
The generation based update mechanism of NixOS is not suited for appliances.
Updates of appliances are usually either performed by replacing the entire
image with a new one or by updating partitions via an A/B scheme. See the
Chrome OS update process for an example of how to achieve
this. The appliance image built in the following example does not contain a
configuration.nix
and thus you will not be able to call nixos-rebuild
from
this system. Furthermore, it uses a Unified Kernel Image.
let
pkgs = import <nixpkgs> { };
efiArch = pkgs.stdenv.hostPlatform.efiArch;
in
(pkgs.nixos [
({ config, lib, pkgs, modulesPath, ... }: {
imports = [ "${modulesPath}/image/repart.nix" ];
boot.loader.grub.enable = false;
fileSystems."/".device = "/dev/disk/by-label/nixos";
image.repart = {
name = "image";
partitions = {
"esp" = {
contents = {
"/EFI/BOOT/BOOT${lib.toUpper efiArch}.EFI".source =
"${pkgs.systemd}/lib/systemd/boot/efi/systemd-boot${efiArch}.efi";
"/EFI/Linux/${config.system.boot.loader.ukiFile}".source =
"${config.system.build.uki}/${config.system.boot.loader.ukiFile}";
};
repartConfig = {
Type = "esp";
Format = "vfat";
SizeMinBytes = "96M";
};
};
"root" = {
storePaths = [ config.system.build.toplevel ];
repartConfig = {
Type = "root";
Format = "ext4";
Label = "nixos";
Minimize = "guess";
};
};
};
};
})
]).image
This chapter describes how to configure various aspects of a NixOS machine through the configuration file /etc/nixos/configuration.nix
. As described in Changing the Configuration, changes to this file only take effect after you run nixos-rebuild.
Table of Contents
Table of Contents
The NixOS configuration file /etc/nixos/configuration.nix
is actually
a Nix expression, which is the Nix package manager’s purely functional
language for describing how to build packages and configurations. This
means you have all the expressive power of that language at your
disposal, including the ability to abstract over common patterns, which
is very useful when managing complex systems. The syntax and semantics
of the Nix language are fully described in the Nix
manual, but
here we give a short overview of the most important constructs useful in
NixOS configuration files.
The NixOS configuration file generally looks like this:
{ config, pkgs, ... }:
{ /* option definitions */
}
The first line ({ config, pkgs, ... }:
) denotes that this is actually
a function that takes at least the two arguments config
and pkgs
.
(These are explained later, in chapter Writing NixOS Modules) The
function returns a set of option definitions ({ ... }
).
These definitions have the form name = value
, where name
is the
name of an option and value
is its value. For example,
{ config, pkgs, ... }:
{ services.httpd.enable = true;
services.httpd.adminAddr = "alice@example.org";
services.httpd.virtualHosts.localhost.documentRoot = "/webroot";
}
defines a configuration with three option definitions that together
enable the Apache HTTP Server with /webroot
as the document root.
Sets can be nested, and in fact dots in option names are shorthand for
defining a set containing another set. For instance,
services.httpd.enable
defines a set named
services
that contains a set named httpd
, which in turn contains an
option definition named enable
with value true
. This means that the
example above can also be written as:
{ config, pkgs, ... }:
{ services = {
httpd = {
enable = true;
adminAddr = "alice@example.org";
virtualHosts = {
localhost = {
documentRoot = "/webroot";
};
};
};
};
}
which may be more convenient if you have lots of option definitions that
share the same prefix (such as services.httpd
).
NixOS checks your option definitions for correctness. For instance, if
you try to define an option that doesn’t exist (that is, doesn’t have a
corresponding option declaration), nixos-rebuild
will give an error
like:
The option `services.httpd.enable' defined in `/etc/nixos/configuration.nix' does not exist.
Likewise, values in option definitions must have a correct type. For
instance, services.httpd.enable
must be a Boolean (true
or false
).
Trying to give it a value of another type, such as a string, will cause
an error:
The option value `services.httpd.enable' in `/etc/nixos/configuration.nix' is not a boolean.
Options have various types of values. The most important are:
Strings are enclosed in double quotes, e.g.
{
networking.hostName = "dexter";
}
Special characters can be escaped by prefixing them with a backslash
(e.g. \"
).
Multi-line strings can be enclosed in double single quotes, e.g.
{
networking.extraHosts =
''
127.0.0.2 other-localhost
10.0.0.1 server
'';
}
The main difference is that it strips from each line a number of
spaces equal to the minimal indentation of the string as a whole
(disregarding the indentation of empty lines), and that characters
like "
and \
are not special (making it more convenient for
including things like shell code). See more info about this in the
Nix manual here.
These can be true
or false
, e.g.
{
networking.firewall.enable = true;
networking.firewall.allowPing = false;
}
For example,
{
boot.kernel.sysctl."net.ipv4.tcp_keepalive_time" = 60;
}
(Note that here the attribute name net.ipv4.tcp_keepalive_time
is
enclosed in quotes to prevent it from being interpreted as a set
named net
containing a set named ipv4
, and so on. This is
because it’s not a NixOS option but the literal name of a Linux
kernel setting.)
Sets were introduced above. They are name/value pairs enclosed in braces, as in the option definition
{
fileSystems."/boot" =
{ device = "/dev/sda1";
fsType = "ext4";
options = [ "rw" "data=ordered" "relatime" ];
};
}
The important thing to note about lists is that list elements are separated by whitespace, like this:
{
boot.kernelModules = [ "fuse" "kvm-intel" "coretemp" ];
}
List elements can be any other type, e.g. sets:
{
swapDevices = [ { device = "/dev/disk/by-label/swap"; } ];
}
Usually, the packages you need are already part of the Nix Packages
collection, which is a set that can be accessed through the function
argument pkgs
. Typical uses:
{
environment.systemPackages =
[ pkgs.thunderbird
pkgs.emacs
];
services.postgresql.package = pkgs.postgresql_14;
}
The latter option definition changes the default PostgreSQL package used by NixOS’s PostgreSQL service to 14.x. For more information on packages, including how to add new ones, see the section called “Adding Custom Packages”.
If you find yourself repeating yourself over and over, it’s time to abstract. Take, for instance, this Apache HTTP Server configuration:
{
services.httpd.virtualHosts =
{ "blog.example.org" = {
documentRoot = "/webroot/blog.example.org";
adminAddr = "alice@example.org";
forceSSL = true;
enableACME = true;
};
"wiki.example.org" = {
documentRoot = "/webroot/wiki.example.org";
adminAddr = "alice@example.org";
forceSSL = true;
enableACME = true;
};
};
}
It defines two virtual hosts with nearly identical configuration; the only difference is the document root directories. To prevent this duplication, we can use a let
:
let
commonConfig =
{ adminAddr = "alice@example.org";
forceSSL = true;
enableACME = true;
};
in
{
services.httpd.virtualHosts =
{ "blog.example.org" = (commonConfig // { documentRoot = "/webroot/blog.example.org"; });
"wiki.example.org" = (commonConfig // { documentRoot = "/webroot/wiki.example.org"; });
};
}
The let commonConfig = ...
defines a variable named commonConfig
. The //
operator merges two attribute sets, so the configuration of the second virtual host is the set commonConfig
extended with the document root option.
You can write a let
wherever an expression is allowed. Thus, you also could have written:
{
services.httpd.virtualHosts =
let commonConfig = { /* ... */ }; in
{ "blog.example.org" = (commonConfig // { /* ... */ });
"wiki.example.org" = (commonConfig // { /* ... */ });
};
}
but not { let commonConfig = ...; in ...; }
since attributes (as opposed to attribute values) are not expressions.
Functions provide another method of abstraction. For instance, suppose that we want to generate lots of different virtual hosts, all with identical configuration except for the document root. This can be done as follows:
{
services.httpd.virtualHosts =
let
makeVirtualHost = webroot:
{ documentRoot = webroot;
adminAddr = "alice@example.org";
forceSSL = true;
enableACME = true;
};
in
{ "example.org" = (makeVirtualHost "/webroot/example.org");
"example.com" = (makeVirtualHost "/webroot/example.com");
"example.gov" = (makeVirtualHost "/webroot/example.gov");
"example.nl" = (makeVirtualHost "/webroot/example.nl");
};
}
Here, makeVirtualHost
is a function that takes a single argument webroot
and returns the configuration for a virtual host. That function is then called for several names to produce the list of virtual host configurations.
The NixOS configuration mechanism is modular. If your
configuration.nix
becomes too big, you can split it into multiple
files. Likewise, if you have multiple NixOS configurations (e.g. for
different computers) with some commonality, you can move the common
configuration into a shared file.
Modules have exactly the same syntax as configuration.nix
. In fact,
configuration.nix
is itself a module. You can use other modules by
including them from configuration.nix
, e.g.:
{ config, pkgs, ... }:
{ imports = [ ./vpn.nix ./kde.nix ];
services.httpd.enable = true;
environment.systemPackages = [ pkgs.emacs ];
# ...
}
Here, we include two modules from the same directory, vpn.nix
and
kde.nix
. The latter might look like this:
{ config, pkgs, ... }:
{ services.xserver.enable = true;
services.displayManager.sddm.enable = true;
services.xserver.desktopManager.plasma5.enable = true;
environment.systemPackages = [ pkgs.vim ];
}
Note that both configuration.nix
and kde.nix
define the option
environment.systemPackages
. When multiple modules define an
option, NixOS will try to merge the definitions. In the case of
environment.systemPackages
the lists of packages will be
concatenated. The value in configuration.nix
is
merged last, so for list-type options, it will appear at the end of the
merged list. If you want it to appear first, you can use mkBefore
:
{
boot.kernelModules = mkBefore [ "kvm-intel" ];
}
This causes the kvm-intel
kernel module to be loaded before any other
kernel modules.
For other types of options, a merge may not be possible. For instance,
if two modules define services.httpd.adminAddr
,
nixos-rebuild
will give an error:
The unique option `services.httpd.adminAddr' is defined multiple times, in `/etc/nixos/httpd.nix' and `/etc/nixos/configuration.nix'.
When that happens, it’s possible to force one definition take precedence over the others:
{
services.httpd.adminAddr = pkgs.lib.mkForce "bob@example.org";
}
When using multiple modules, you may need to access configuration values
defined in other modules. This is what the config
function argument is
for: it contains the complete, merged system configuration. That is,
config
is the result of combining the configurations returned by every
module. (If you’re wondering how it’s possible that the (indirect) result
of a function is passed as an input to that same function: that’s
because Nix is a “lazy” language — it only computes values when
they are needed. This works as long as no individual configuration
value depends on itself.)
For example, here is a module that adds some packages to
environment.systemPackages
only if
services.xserver.enable
is set to true
somewhere else:
{ config, pkgs, ... }:
{ environment.systemPackages =
if config.services.xserver.enable then
[ pkgs.firefox
pkgs.thunderbird
]
else
[ ];
}
With multiple modules, it may not be obvious what the final value of a
configuration option is. The command nixos-option
allows you to find
out:
$ nixos-option services.xserver.enable
true
$ nixos-option boot.kernelModules
[ "tun" "ipv6" "loop" ... ]
Interactive exploration of the configuration is possible using nix repl
, a read-eval-print loop for Nix expressions. A typical use:
$ nix repl '<nixpkgs/nixos>'
nix-repl> config.networking.hostName
"mandark"
nix-repl> map (x: x.hostName) config.services.httpd.virtualHosts
[ "example.org" "example.gov" ]
While abstracting your configuration, you may find it useful to generate modules using code, instead of writing files. The example below would have the same effect as importing a file which sets those options.
{ config, pkgs, ... }:
let netConfig = hostName: {
networking.hostName = hostName;
networking.useDHCP = false;
};
in
{ imports = [ (netConfig "nixos.localdomain") ]; }
Table of Contents
This section describes how to add additional packages to your system. NixOS has two distinct styles of package management:
Declarative, where you declare what packages you want in your
configuration.nix
. Every time you run nixos-rebuild
, NixOS will
ensure that you get a consistent set of binaries corresponding to
your specification.
Ad hoc, where you install, upgrade and uninstall packages via the
nix-env
command. This style allows mixing packages from different
Nixpkgs versions. It’s the only choice for non-root users.
With declarative package management, you specify which packages you want
on your system by setting the option
environment.systemPackages
. For instance, adding the
following line to configuration.nix
enables the Mozilla Thunderbird
email application:
{
environment.systemPackages = [ pkgs.thunderbird ];
}
The effect of this specification is that the Thunderbird package from
Nixpkgs will be built or downloaded as part of the system when you run
nixos-rebuild switch
.
Some packages require additional global configuration such as D-Bus or
systemd service registration so adding them to
environment.systemPackages
might not be sufficient. You are
advised to check the list of options whether a NixOS
module for the package does not exist.
You can get a list of the available packages as follows:
$ nix-env -qaP '*' --description
nixos.firefox firefox-23.0 Mozilla Firefox - the browser, reloaded
...
The first column in the output is the attribute name, such as
nixos.thunderbird
.
Note: the nixos
prefix tells us that we want to get the package from
the nixos
channel and works only in CLI tools. In declarative
configuration use pkgs
prefix (variable).
To “uninstall” a package, remove it from
environment.systemPackages
and run nixos-rebuild switch
.
The Nixpkgs configuration for a NixOS system is set by the nixpkgs.config
option.
{
nixpkgs.config = {
allowUnfree = true;
};
}
This only allows unfree software in the given NixOS configuration.
For users invoking Nix commands such as nix-build
, Nixpkgs is configured independently.
See the Nixpkgs manual section on global configuration for details.
Some packages in Nixpkgs have options to enable or disable optional functionality, or change other aspects of the package.
Unfortunately, Nixpkgs currently lacks a way to query available package configuration options.
For example, many packages come with extensions one might add. Examples include:
You can use them like this:
{
environment.systemPackages = with pkgs; [
sl
(pass.withExtensions (subpkgs: with subpkgs; [
pass-audit
pass-otp
pass-genphrase
]))
(python3.withPackages (subpkgs: with subpkgs; [
requests
]))
cowsay
];
}
Apart from high-level options, it’s possible to tweak a package in almost arbitrary ways, such as changing or disabling dependencies of a package. For instance, the Emacs package in Nixpkgs by default has a dependency on GTK 2. If you want to build it against GTK 3, you can specify that as follows:
{
environment.systemPackages = [ (pkgs.emacs.override { gtk = pkgs.gtk3; }) ];
}
The function override
performs the call to the Nix function that
produces Emacs, with the original arguments amended by the set of
arguments specified by you. So here the function argument gtk
gets the
value pkgs.gtk3
, causing Emacs to depend on GTK 3. (The parentheses
are necessary because in Nix, function application binds more weakly
than list construction, so without them,
environment.systemPackages
would be a list with two elements.)
Even greater customisation is possible using the function
overrideAttrs
. While the override
mechanism above overrides the
arguments of a package function, overrideAttrs
allows changing the
attributes passed to mkDerivation
. This permits changing any aspect
of the package, such as the source code. For instance, if you want to
override the source code of Emacs, you can say:
{
environment.systemPackages = [
(pkgs.emacs.overrideAttrs (oldAttrs: {
name = "emacs-25.0-pre";
src = /path/to/my/emacs/tree;
}))
];
}
Here, overrideAttrs
takes the Nix derivation specified by pkgs.emacs
and produces a new derivation in which the original’s name
and src
attribute have been replaced by the given values by re-calling
stdenv.mkDerivation
. The original attributes are accessible via the
function argument, which is conventionally named oldAttrs
.
The overrides shown above are not global. They do not affect the original package; other packages in Nixpkgs continue to depend on the original rather than the customised package. This means that if another package in your system depends on the original package, you end up with two instances of the package. If you want to have everything depend on your customised instance, you can apply a global override as follows:
{
nixpkgs.config.packageOverrides = pkgs:
{ emacs = pkgs.emacs.override { gtk = pkgs.gtk3; };
};
}
The effect of this definition is essentially equivalent to modifying the
emacs
attribute in the Nixpkgs source tree. Any package in Nixpkgs
that depends on emacs
will be passed your customised instance.
(However, the value pkgs.emacs
in nixpkgs.config.packageOverrides
refers to the original rather than overridden instance, to prevent an
infinite recursion.)
It’s possible that a package you need is not available in NixOS. In that case, you can do two things. Either you can package it with Nix, or you can try to use prebuilt packages from upstream. Due to the peculiarities of NixOS, it is important to note that building software from source is often easier than using pre-built executables.
This can be done either in-tree or out-of-tree. For an in-tree build, you can clone the Nixpkgs repository, add the package to your clone, and (optionally) submit a patch or pull request to have it accepted into the main Nixpkgs repository. This is described in detail in the Nixpkgs manual. In short, you clone Nixpkgs:
$ git clone https://github.com/NixOS/nixpkgs
$ cd nixpkgs
Then you write and test the package as described in the Nixpkgs manual.
Finally, you add it to environment.systemPackages
, e.g.
{
environment.systemPackages = [ pkgs.my-package ];
}
and you run nixos-rebuild
, specifying your own Nixpkgs tree:
# nixos-rebuild switch -I nixpkgs=/path/to/my/nixpkgs
The second possibility is to add the package outside of the Nixpkgs
tree. For instance, here is how you specify a build of the
GNU Hello package directly in
configuration.nix
:
{
environment.systemPackages =
let
my-hello = with pkgs; stdenv.mkDerivation rec {
name = "hello-2.8";
src = fetchurl {
url = "mirror://gnu/hello/${name}.tar.gz";
hash = "sha256-5rd/gffPfa761Kn1tl3myunD8TuM+66oy1O7XqVGDXM=";
};
};
in
[ my-hello ];
}
Of course, you can also move the definition of my-hello
into a
separate Nix expression, e.g.
{
environment.systemPackages = [ (import ./my-hello.nix) ];
}
where my-hello.nix
contains:
with import <nixpkgs> {}; # bring all of Nixpkgs into scope
stdenv.mkDerivation rec {
name = "hello-2.8";
src = fetchurl {
url = "mirror://gnu/hello/${name}.tar.gz";
hash = "sha256-5rd/gffPfa761Kn1tl3myunD8TuM+66oy1O7XqVGDXM=";
};
}
This allows testing the package easily:
$ nix-build my-hello.nix
$ ./result/bin/hello
Hello, world!
Most pre-built executables will not work on NixOS. There are two notable
exceptions: flatpaks and AppImages. For flatpaks see the dedicated
section. AppImages will not run “as-is” on NixOS.
First you need to install appimage-run
: add to /etc/nixos/configuration.nix
{
environment.systemPackages = [ pkgs.appimage-run ];
}
Then instead of running the AppImage “as-is”, run appimage-run foo.appimage
.
To make other pre-built executables work on NixOS, you need to package them
with Nix and special helpers like autoPatchelfHook
or buildFHSEnv
. See
the Nixpkgs manual for details. This
is complex and often doing a source build is easier.
With the command nix-env
, you can install and uninstall packages from
the command line. For instance, to install Mozilla Thunderbird:
$ nix-env -iA nixos.thunderbird
If you invoke this as root, the package is installed in the Nix profile
/nix/var/nix/profiles/default
and visible to all users of the system;
otherwise, the package ends up in
/nix/var/nix/profiles/per-user/username/profile
and is not visible to
other users. The -A
flag specifies the package by its attribute name;
without it, the package is installed by matching against its package
name (e.g. thunderbird
). The latter is slower because it requires
matching against all available Nix packages, and is ambiguous if there
are multiple matching packages.
Packages come from the NixOS channel. You typically upgrade a package by updating to the latest version of the NixOS channel:
$ nix-channel --update nixos
and then running nix-env -i
again. Other packages in the profile are
not affected; this is the crucial difference with the declarative
style of package management, where running nixos-rebuild switch
causes
all packages to be updated to their current versions in the NixOS
channel. You can however upgrade all packages for which there is a newer
version by doing:
$ nix-env -u '*'
A package can be uninstalled using the -e
flag:
$ nix-env -e thunderbird
Finally, you can roll back an undesirable nix-env
action:
$ nix-env --rollback
nix-env
has many more flags. For details, see the nix-env(1) manpage or
the Nix manual.
Table of Contents
NixOS supports both declarative and imperative styles of user
management. In the declarative style, users are specified in
configuration.nix
. For instance, the following states that a user
account named alice
shall exist:
{
users.users.alice = {
isNormalUser = true;
home = "/home/alice";
description = "Alice Foobar";
extraGroups = [ "wheel" "networkmanager" ];
openssh.authorizedKeys.keys = [ "ssh-dss AAAAB3Nza... alice@foobar" ];
};
}
Note that alice
is a member of the wheel
and networkmanager
groups, which allows her to use sudo
to execute commands as root
and
to configure the network, respectively. Also note the SSH public key
that allows remote logins with the corresponding private key. Users
created in this way do not have a password by default, so they cannot
log in via mechanisms that require a password. However, you can use the
passwd
program to set a password, which is retained across invocations
of nixos-rebuild
.
If you set users.mutableUsers
to
false, then the contents of /etc/passwd
and /etc/group
will be congruent
to your NixOS configuration. For instance, if you remove a user from
users.users
and run nixos-rebuild, the user
account will cease to exist. Also, imperative commands for managing users and
groups, such as useradd, are no longer available. Passwords may still be
assigned by setting the user’s
hashedPassword option. A
hashed password can be generated using mkpasswd
.
A user ID (uid) is assigned automatically. You can also specify a uid manually by adding
{
uid = 1000;
}
to the user specification.
Groups can be specified similarly. The following states that a group
named students
shall exist:
{
users.groups.students.gid = 1000;
}
As with users, the group ID (gid) is optional and will be assigned automatically if it’s missing.
In the imperative style, users and groups are managed by commands such
as useradd
, groupmod
and so on. For instance, to create a user
account named alice
:
# useradd -m alice
To make all nix tools available to this new user use `su - USER` which opens a login shell (==shell that loads the profile) for given user. This will create the ~/.nix-defexpr symlink. So run:
# su - alice -c "true"
The flag -m
causes the creation of a home directory for the new user,
which is generally what you want. The user does not have an initial
password and therefore cannot log in. A password can be set using the
passwd
utility:
# passwd alice
Enter new UNIX password: ***
Retype new UNIX password: ***
A user can be deleted using userdel
:
# userdel -r alice
The flag -r
deletes the user’s home directory. Accounts can be
modified using usermod
. Unix groups can be managed using groupadd
,
groupmod
and groupdel
.
systemd-sysusers
This is experimental.
Instead of using a custom perl script to create users and groups, you can use systemd-sysusers:
{
systemd.sysusers.enable = true;
}
The primary benefit of this is to remove a dependency on perl.
Table of Contents
You can define file systems using the fileSystems
configuration
option. For instance, the following definition causes NixOS to mount the
Ext4 file system on device /dev/disk/by-label/data
onto the mount
point /data
:
{
fileSystems."/data" =
{ device = "/dev/disk/by-label/data";
fsType = "ext4";
};
}
This will create an entry in /etc/fstab
, which will generate a
corresponding systemd.mount
unit via systemd-fstab-generator.
The filesystem will be mounted automatically unless "noauto"
is
present in options. "noauto"
filesystems can be mounted explicitly using systemctl
e.g.
systemctl start data.mount
. Mount points are created automatically if they don’t
already exist. For device
, it’s best to use the topology-independent
device aliases in /dev/disk/by-label
and /dev/disk/by-uuid
, as these
don’t change if the topology changes (e.g. if a disk is moved to another
IDE controller).
You can usually omit the file system type (fsType
), since mount
can
usually detect the type and load the necessary kernel module
automatically. However, if the file system is needed at early boot (in
the initial ramdisk) and is not ext2
, ext3
or ext4
, then it’s best
to specify fsType
to ensure that the kernel module is available.
System startup will fail if any of the filesystems fails to mount,
dropping you to the emergency shell. You can make a mount asynchronous
and non-critical by adding options = [ "nofail" ];
.
NixOS supports file systems that are encrypted using LUKS (Linux
Unified Key Setup). For example, here is how you create an encrypted
Ext4 file system on the device
/dev/disk/by-uuid/3f6b0024-3a44-4fde-a43a-767b872abe5d
:
# cryptsetup luksFormat /dev/disk/by-uuid/3f6b0024-3a44-4fde-a43a-767b872abe5d
WARNING!
========
This will overwrite data on /dev/disk/by-uuid/3f6b0024-3a44-4fde-a43a-767b872abe5d irrevocably.
Are you sure? (Type uppercase yes): YES
Enter LUKS passphrase: ***
Verify passphrase: ***
# cryptsetup luksOpen /dev/disk/by-uuid/3f6b0024-3a44-4fde-a43a-767b872abe5d crypted
Enter passphrase for /dev/disk/by-uuid/3f6b0024-3a44-4fde-a43a-767b872abe5d: ***
# mkfs.ext4 /dev/mapper/crypted
The LUKS volume should be automatically picked up by
nixos-generate-config
, but you might want to verify that your
hardware-configuration.nix
looks correct. To manually ensure that the
system is automatically mounted at boot time as /
, add the following
to configuration.nix
:
{
boot.initrd.luks.devices.crypted.device = "/dev/disk/by-uuid/3f6b0024-3a44-4fde-a43a-767b872abe5d";
fileSystems."/".device = "/dev/mapper/crypted";
}
Should grub be used as bootloader, and /boot
is located on an
encrypted partition, it is necessary to add the following grub option:
{
boot.loader.grub.enableCryptodisk = true;
}
NixOS also supports unlocking your LUKS-Encrypted file system using a FIDO2 compatible token.
In the following example, we will create a new
FIDO2 credential and add it as a new key to our existing device
/dev/sda2
:
# export FIDO2_LABEL="/dev/sda2 @ $HOSTNAME"
# fido2luks credential "$FIDO2_LABEL"
f1d00200108b9d6e849a8b388da457688e3dd653b4e53770012d8f28e5d3b269865038c346802f36f3da7278b13ad6a3bb6a1452e24ebeeaa24ba40eef559b1b287d2a2f80b7
# fido2luks -i add-key /dev/sda2 f1d00200108b9d6e849a8b388da457688e3dd653b4e53770012d8f28e5d3b269865038c346802f36f3da7278b13ad6a3bb6a1452e24ebeeaa24ba40eef559b1b287d2a2f80b7
Password:
Password (again):
Old password:
Old password (again):
Added to key to device /dev/sda2, slot: 2
To ensure that this file system is decrypted using the FIDO2 compatible
key, add the following to configuration.nix
:
{
boot.initrd.luks.fido2Support = true;
boot.initrd.luks.devices."/dev/sda2".fido2.credential = "f1d00200108b9d6e849a8b388da457688e3dd653b4e53770012d8f28e5d3b269865038c346802f36f3da7278b13ad6a3bb6a1452e24ebeeaa24ba40eef559b1b287d2a2f80b7";
}
You can also use the FIDO2 passwordless setup, but for security reasons, you might want to enable it only when your device is PIN protected, such as Trezor.
{
boot.initrd.luks.devices."/dev/sda2".fido2.passwordLess = true;
}
If systemd stage 1 is enabled, it handles unlocking of LUKS-enrypted volumes
during boot. The following example enables systemd stage1 and adds support for
unlocking the existing LUKS2 volume root
using any enrolled FIDO2 compatible
tokens.
{
boot.initrd = {
luks.devices.root = {
crypttabExtraOpts = [ "fido2-device=auto" ];
device = "/dev/sda2";
};
systemd.enable = true;
};
}
All tokens that should be used for unlocking the LUKS2-encrypted volume must first be enrolled using systemd-cryptenroll. In the following example, a new key slot for the first discovered token is added to the LUKS volume.
# systemd-cryptenroll --fido2-device=auto /dev/sda2
Existing key slots are left intact, unless --wipe-slot=
is specified. It is
recommened to add a recovery key that should be stored in a secure physical
location and can be entered wherever a password would be entered.
# systemd-cryptenroll --recovery-key /dev/sda2
SSHFS is a FUSE filesystem that allows easy access to directories on a remote machine using the SSH File Transfer Protocol (SFTP). It means that if you have SSH access to a machine, no additional setup is needed to mount a directory.
In NixOS, SSHFS is packaged as sshfs
.
Once installed, mounting a directory interactively is simple as running:
$ sshfs my-user@example.com:/my-dir /mnt/my-dir
Like any other FUSE file system, the directory is unmounted using:
$ fusermount -u /mnt/my-dir
Mounting non-interactively requires some precautions because sshfs
will run at boot and under a different user (root).
For obvious reason, you can’t input a password, so public key authentication using an unencrypted key is needed.
To create a new key without a passphrase you can do:
$ ssh-keygen -t ed25519 -P '' -f example-key
Generating public/private ed25519 key pair.
Your identification has been saved in example-key
Your public key has been saved in example-key.pub
The key fingerprint is:
SHA256:yjxl3UbTn31fLWeyLYTAKYJPRmzknjQZoyG8gSNEoIE my-user@workstation
To keep the key safe, change the ownership to root:root
and make sure the permissions are 600
:
OpenSSH normally refuses to use the key if it’s not well-protected.
The file system can be configured in NixOS via the usual fileSystems option. Here’s a typical setup:
{
fileSystems."/mnt/my-dir" = {
device = "my-user@example.com:/my-dir/";
fsType = "sshfs";
options =
[ # Filesystem options
"allow_other" # for non-root access
"_netdev" # this is a network fs
"x-systemd.automount" # mount on demand
# SSH options
"reconnect" # handle connection drops
"ServerAliveInterval=15" # keep connections alive
"IdentityFile=/var/secrets/example-key"
];
};
}
More options from ssh_config(5)
can be given as well, for example you can change the default SSH port or specify a jump proxy:
{
options =
[ "ProxyJump=bastion@example.com"
"Port=22"
];
}
It’s also possible to change the ssh
command used by SSHFS to connect to the server.
For example:
{
options =
[ (builtins.replaceStrings [" "] ["\\040"]
"ssh_command=${pkgs.openssh}/bin/ssh -v -L 8080:localhost:80")
];
}
The escaping of spaces is needed because every option is written to the /etc/fstab
file, which is a space-separated table.
If you’re having a hard time figuring out why mounting is failing, you can add the option "debug"
.
This enables a verbose log in SSHFS that you can access via:
$ journalctl -u $(systemd-escape -p /mnt/my-dir/).mount
Jun 22 11:41:18 workstation mount[87790]: SSHFS version 3.7.1
Jun 22 11:41:18 workstation mount[87793]: executing <ssh> <-x> <-a> <-oClearAllForwardings=yes> <-oServerAliveInterval=15> <-oIdentityFile=/var/secrets/wrong-key> <-2> <my-user@example.com> <-s> <sftp>
Jun 22 11:41:19 workstation mount[87793]: my-user@example.com: Permission denied (publickey).
Jun 22 11:41:19 workstation mount[87790]: read: Connection reset by peer
Jun 22 11:41:19 workstation systemd[1]: mnt-my\x2ddir.mount: Mount process exited, code=exited, status=1/FAILURE
Jun 22 11:41:19 workstation systemd[1]: mnt-my\x2ddir.mount: Failed with result 'exit-code'.
Jun 22 11:41:19 workstation systemd[1]: Failed to mount /mnt/my-dir.
Jun 22 11:41:19 workstation systemd[1]: mnt-my\x2ddir.mount: Consumed 54ms CPU time, received 2.3K IP traffic, sent 2.7K IP traffic.
If the mount point contains special characters it needs to be escaped using systemd-escape
.
This is due to the way systemd converts paths into unit names.
NixOS offers a convenient abstraction to create both read-only as well writable overlays.
{
fileSystems = {
"/writable-overlay" = {
overlay = {
lowerdir = [ writableOverlayLowerdir ];
upperdir = "/.rw-writable-overlay/upper";
workdir = "/.rw-writable-overlay/work";
};
# Mount the writable overlay in the initrd.
neededForBoot = true;
};
"/readonly-overlay".overlay.lowerdir = [
writableOverlayLowerdir
writableOverlayLowerdir2
];
};
}
If upperdir
and workdir
are not null, they will be created before the
overlay is mounted.
To mount an overlay as read-only, you need to provide at least two lowerdir
s.
Table of Contents
The X Window System (X11) provides the basis of NixOS’ graphical user interface. It can be enabled as follows:
{
services.xserver.enable = true;
}
The X server will automatically detect and use the appropriate video
driver from a set of X.org drivers (such as vesa
and intel
). You can
also specify a driver manually, e.g.
{
services.xserver.videoDrivers = [ "r128" ];
}
to enable X.org’s xf86-video-r128
driver.
You also need to enable at least one desktop or window manager.
Otherwise, you can only log into a plain undecorated xterm
window.
Thus you should pick one or more of the following lines:
{
services.xserver.desktopManager.plasma5.enable = true;
services.xserver.desktopManager.xfce.enable = true;
services.xserver.desktopManager.gnome.enable = true;
services.xserver.desktopManager.mate.enable = true;
services.xserver.windowManager.xmonad.enable = true;
services.xserver.windowManager.twm.enable = true;
services.xserver.windowManager.icewm.enable = true;
services.xserver.windowManager.i3.enable = true;
services.xserver.windowManager.herbstluftwm.enable = true;
}
NixOS’s default display manager (the program that provides a graphical login prompt and manages the X server) is LightDM. You can select an alternative one by picking one of the following lines:
{
services.displayManager.sddm.enable = true;
services.xserver.displayManager.gdm.enable = true;
}
You can set the keyboard layout (and optionally the layout variant):
{
services.xserver.xkb.layout = "de";
services.xserver.xkb.variant = "neo";
}
The X server is started automatically at boot time. If you don’t want this to happen, you can set:
{
services.xserver.autorun = false;
}
The X server can then be started manually:
# systemctl start display-manager.service
On 64-bit systems, if you want OpenGL for 32-bit programs such as in Wine, you should also set the following:
{
hardware.opengl.driSupport32Bit = true;
}
The x11 login screen can be skipped entirely, automatically logging you into your window manager and desktop environment when you boot your computer.
This is especially helpful if you have disk encryption enabled. Since you already have to provide a password to decrypt your disk, entering a second password to login can be redundant.
To enable auto-login, you need to define your default window manager and desktop environment. If you wanted no desktop environment and i3 as your your window manager, you’d define:
{
services.displayManager.defaultSession = "none+i3";
}
Every display manager in NixOS supports auto-login, here is an example
using lightdm for a user alice
:
{
services.xserver.displayManager.lightdm.enable = true;
services.displayManager.autoLogin.enable = true;
services.displayManager.autoLogin.user = "alice";
}
There are two choices for Intel Graphics drivers in X.org: modesetting
(included in the xorg-server itself) and intel
(provided by the
package xf86-video-intel).
The default and recommended is modesetting
. It is a generic driver
which uses the kernel mode
setting (KMS) mechanism. It
supports Glamor (2D graphics acceleration via OpenGL) and is actively
maintained but may perform worse in some cases (like in old chipsets).
The second driver, intel
, is specific to Intel GPUs, but not
recommended by most distributions: it lacks several modern features (for
example, it doesn’t support Glamor) and the package hasn’t been
officially updated since 2015.
The results vary depending on the hardware, so you may have to try both
drivers. Use the option
services.xserver.videoDrivers
to set one. The recommended configuration for modern systems is:
{
services.xserver.videoDrivers = [ "modesetting" ];
}
If you experience screen tearing no matter what, this configuration was reported to resolve the issue:
{
services.xserver.videoDrivers = [ "intel" ];
services.xserver.deviceSection = ''
Option "DRI" "2"
Option "TearFree" "true"
'';
}
Note that this will likely downgrade the performance compared to
modesetting
or intel
with DRI 3 (default).
NVIDIA provides a proprietary driver for its graphics cards that has better 3D performance than the X.org drivers. It is not enabled by default because it’s not free software. You can enable it as follows:
{
services.xserver.videoDrivers = [ "nvidia" ];
}
If you have an older card, you may have to use one of the legacy drivers:
{
hardware.nvidia.package = config.boot.kernelPackages.nvidiaPackages.legacy_470;
hardware.nvidia.package = config.boot.kernelPackages.nvidiaPackages.legacy_390;
hardware.nvidia.package = config.boot.kernelPackages.nvidiaPackages.legacy_340;
}
You may need to reboot after enabling this driver to prevent a clash with other kernel modules.
AMD provides a proprietary driver for its graphics cards that is not enabled by default because it’s not Free Software, is often broken in nixpkgs and as of this writing doesn’t offer more features or performance. If you still want to use it anyway, you need to explicitly set:
{
services.xserver.videoDrivers = [ "amdgpu-pro" ];
}
You will need to reboot after enabling this driver to prevent a clash with other kernel modules.
Support for Synaptics touchpads (found in many laptops such as the Dell Latitude series) can be enabled as follows:
{
services.libinput.enable = true;
}
The driver has many options (see Appendix A). For instance, the following disables tap-to-click behavior:
{
services.libinput.touchpad.tapping = false;
}
Note: the use of services.xserver.synaptics
is deprecated since NixOS
17.09.
GTK themes can be installed either to user profile or system-wide (via
environment.systemPackages
). To make Qt 5 applications look similar to
GTK ones, you can use the following configuration:
{
qt.enable = true;
qt.platformTheme = "gtk2";
qt.style = "gtk2";
}
It is possible to install custom XKB
keyboard layouts
using the option services.xserver.xkb.extraLayouts
.
As a first example, we are going to create a layout based on the basic US layout, with an additional layer to type some greek symbols by pressing the right-alt key.
Create a file called us-greek
with the following content (under a
directory called symbols
; it’s an XKB peculiarity that will help with
testing):
xkb_symbols "us-greek"
{
include "us(basic)" // includes the base US keys
include "level3(ralt_switch)" // configures right alt as a third level switch
key <LatA> { [ a, A, Greek_alpha ] };
key <LatB> { [ b, B, Greek_beta ] };
key <LatG> { [ g, G, Greek_gamma ] };
key <LatD> { [ d, D, Greek_delta ] };
key <LatZ> { [ z, Z, Greek_zeta ] };
};
A minimal layout specification must include the following:
{
services.xserver.xkb.extraLayouts.us-greek = {
description = "US layout with alt-gr greek";
languages = [ "eng" ];
symbolsFile = /yourpath/symbols/us-greek;
};
}
The name (after extraLayouts.
) should match the one given to the
xkb_symbols
block.
Applying this customization requires rebuilding several packages, and a broken XKB file can lead to the X session crashing at login. Therefore, you’re strongly advised to test your layout before applying it:
$ nix-shell -p xorg.xkbcomp
$ setxkbmap -I/yourpath us-greek -print | xkbcomp -I/yourpath - $DISPLAY
You can inspect the predefined XKB files for examples:
$ echo "$(nix-build --no-out-link '<nixpkgs>' -A xorg.xkeyboardconfig)/etc/X11/xkb/"
Once the configuration is applied, and you did a logout/login cycle, the
layout should be ready to use. You can try it by e.g. running
setxkbmap us-greek
and then type <alt>+a
(it may not get applied in
your terminal straight away). To change the default, the usual
services.xserver.xkb.layout
option can still be used.
A layout can have several other components besides xkb_symbols
, for
example we will define new keycodes for some multimedia key and bind
these to some symbol.
Use the xev utility from pkgs.xorg.xev
to find the codes of the keys
of interest, then create a media-key
file to hold the keycodes
definitions
xkb_keycodes "media"
{
<volUp> = 123;
<volDown> = 456;
}
Now use the newly define keycodes in media-sym
:
xkb_symbols "media"
{
key.type = "ONE_LEVEL";
key <volUp> { [ XF86AudioLowerVolume ] };
key <volDown> { [ XF86AudioRaiseVolume ] };
}
As before, to install the layout do
{
services.xserver.xkb.extraLayouts.media = {
description = "Multimedia keys remapping";
languages = [ "eng" ];
symbolsFile = /path/to/media-key;
keycodesFile = /path/to/media-sym;
};
}
The function pkgs.writeText <filename> <content>
can be useful if you
prefer to keep the layout definitions inside the NixOS configuration.
Unfortunately, the Xorg server does not (currently) support setting a
keymap directly but relies instead on XKB rules to select the matching
components (keycodes, types, …) of a layout. This means that
components other than symbols won’t be loaded by default. As a
workaround, you can set the keymap using setxkbmap
at the start of the
session with:
{
services.xserver.displayManager.sessionCommands = "setxkbmap -keycodes media";
}
If you are manually starting the X server, you should set the argument
-xkbdir /etc/X11/xkb
, otherwise X won’t find your layout files. For
example with xinit
run
$ xinit -- -xkbdir /etc/X11/xkb
To learn how to write layouts take a look at the XKB documentation . More example layouts can also be found here .
While X11 (see X Window System) is still the primary display technology on NixOS, Wayland support is steadily improving. Where X11 separates the X Server and the window manager, on Wayland those are combined: a Wayland Compositor is like an X11 window manager, but also embeds the Wayland ‘Server’ functionality. This means it is sufficient to install a Wayland Compositor such as sway without separately enabling a Wayland server:
{
programs.sway.enable = true;
}
This installs the sway compositor along with some essential utilities. Now you can start sway from the TTY console.
If you are using a wlroots-based compositor, like sway, and want to be able to share your screen, you might want to activate this option:
{
xdg.portal.wlr.enable = true;
}
and configure Pipewire using
services.pipewire.enable
and related options.
Table of Contents
NixOS provides various APIs that benefit from GPU hardware acceleration, such as VA-API and VDPAU for video playback; OpenGL and Vulkan for 3D graphics; and OpenCL for general-purpose computing. This chapter describes how to set up GPU hardware acceleration (as far as this is not done automatically) and how to verify that hardware acceleration is indeed used.
Most of the aforementioned APIs are agnostic with regards to which display server is used. Consequently, these instructions should apply both to the X Window System and Wayland compositors.
OpenCL is a general compute API. It is used by various applications such as Blender and Darktable to accelerate certain operations.
OpenCL applications load drivers through the Installable Client Driver
(ICD) mechanism. In this mechanism, an ICD file specifies the path to
the OpenCL driver for a particular GPU family. In NixOS, there are two
ways to make ICD files visible to the ICD loader. The first is through
the OCL_ICD_VENDORS
environment variable. This variable can contain a
directory which is scanned by the ICL loader for ICD files. For example:
$ export \
OCL_ICD_VENDORS=`nix-build '<nixpkgs>' --no-out-link -A rocmPackages.clr.icd`/etc/OpenCL/vendors/
The second mechanism is to add the OpenCL driver package to
hardware.opengl.extraPackages
.
This links the ICD file under /run/opengl-driver
, where it will be visible
to the ICD loader.
The proper installation of OpenCL drivers can be verified through the
clinfo
command of the clinfo package. This command will report the
number of hardware devices that is found and give detailed information
for each device:
$ clinfo | head -n3
Number of platforms 1
Platform Name AMD Accelerated Parallel Processing
Platform Vendor Advanced Micro Devices, Inc.
Modern AMD Graphics Core
Next (GCN) GPUs are
supported through the rocmPackages.clr.icd package. Adding this package to
hardware.opengl.extraPackages
enables OpenCL support:
{
hardware.opengl.extraPackages = [
rocmPackages.clr.icd
];
}
Intel Gen8 and later GPUs are supported by the Intel NEO OpenCL runtime that is provided by the intel-compute-runtime package. The proprietary Intel OpenCL runtime, in the intel-ocl package, is an alternative for Gen7 GPUs.
The intel-compute-runtime or intel-ocl package can be added to
hardware.opengl.extraPackages
to enable OpenCL support. For example, for Gen8 and later GPUs, the following
configuration can be used:
{
hardware.opengl.extraPackages = [
intel-compute-runtime
];
}
Vulkan is a graphics and compute API for GPUs. It is used directly by games or indirectly though compatibility layers like DXVK.
By default, if hardware.opengl.driSupport
is enabled, mesa is installed and provides Vulkan for supported hardware.
Similar to OpenCL, Vulkan drivers are loaded through the Installable Client Driver (ICD) mechanism. ICD files for Vulkan are JSON files that specify the path to the driver library and the supported Vulkan version. All successfully loaded drivers are exposed to the application as different GPUs. In NixOS, there are two ways to make ICD files visible to Vulkan applications: an environment variable and a module option.
The first option is through the VK_ICD_FILENAMES
environment variable.
This variable can contain multiple JSON files, separated by :
. For
example:
$ export \
VK_ICD_FILENAMES=`nix-build '<nixpkgs>' --no-out-link -A amdvlk`/share/vulkan/icd.d/amd_icd64.json
The second mechanism is to add the Vulkan driver package to
hardware.opengl.extraPackages
.
This links the ICD file under /run/opengl-driver
, where it will be
visible to the ICD loader.
The proper installation of Vulkan drivers can be verified through the
vulkaninfo
command of the vulkan-tools package. This command will
report the hardware devices and drivers found, in this example output
amdvlk and radv:
$ vulkaninfo | grep GPU
GPU id : 0 (Unknown AMD GPU)
GPU id : 1 (AMD RADV NAVI10 (LLVM 9.0.1))
...
GPU0:
deviceType = PHYSICAL_DEVICE_TYPE_DISCRETE_GPU
deviceName = Unknown AMD GPU
GPU1:
deviceType = PHYSICAL_DEVICE_TYPE_DISCRETE_GPU
A simple graphical application that uses Vulkan is vkcube
from the
vulkan-tools package.
Modern AMD Graphics Core
Next (GCN) GPUs are
supported through either radv, which is part of mesa, or the amdvlk
package. Adding the amdvlk package to
hardware.opengl.extraPackages
makes amdvlk the default driver and hides radv and lavapipe from the device list.
A specific driver can be forced as follows:
{
hardware.opengl.extraPackages = [
pkgs.amdvlk
];
# To enable Vulkan support for 32-bit applications, also add:
hardware.opengl.extraPackages32 = [
pkgs.driversi686Linux.amdvlk
];
# Force radv
environment.variables.AMD_VULKAN_ICD = "RADV";
# Or
environment.variables.VK_ICD_FILENAMES =
"/run/opengl-driver/share/vulkan/icd.d/radeon_icd.x86_64.json";
}
VA-API (Video Acceleration API) is an open-source library and API specification, which provides access to graphics hardware acceleration capabilities for video processing.
VA-API drivers are loaded by libva
. The version in nixpkgs is built to search
the opengl driver path, so drivers can be installed in
hardware.opengl.extraPackages
.
VA-API can be tested using:
$ nix-shell -p libva-utils --run vainfo
Modern Intel GPUs use the iHD driver, which can be installed with:
{
hardware.opengl.extraPackages = [
intel-media-driver
];
}
Older Intel GPUs use the i965 driver, which can be installed with:
{
hardware.opengl.extraPackages = [
intel-vaapi-driver
];
}
Except where noted explicitly, it should not be necessary to adjust user
permissions to use these acceleration APIs. In the default
configuration, GPU devices have world-read/write permissions
(/dev/dri/renderD*
) or are tagged as uaccess
(/dev/dri/card*
). The
access control lists of devices with the uaccess
tag will be updated
automatically when a user logs in through systemd-logind
. For example,
if the user alice is logged in, the access control list should look as
follows:
$ getfacl /dev/dri/card0
# file: dev/dri/card0
# owner: root
# group: video
user::rw-
user:alice:rw-
group::rw-
mask::rw-
other::---
If you disabled (this functionality of) systemd-logind
, you may need
to add the user to the video
group and log in again.
The Installable Client Driver (ICD) mechanism used by OpenCL and
Vulkan loads runtimes into its address space using dlopen
. Mixing an
ICD loader mechanism and runtimes from different version of nixpkgs may
not work. For example, if the ICD loader uses an older version of glibc
than the runtime, the runtime may not be loadable due to missing
symbols. Unfortunately, the loader will generally be quiet about such
issues.
If you suspect that you are running into library version mismatches
between an ICL loader and a runtime, you could run an application with
the LD_DEBUG
variable set to get more diagnostic information. For
example, OpenCL can be tested with LD_DEBUG=files clinfo
, which should
report missing symbols.
Table of Contents
To enable the Xfce Desktop Environment, set
{
services.xserver.desktopManager.xfce.enable = true;
services.displayManager.defaultSession = "xfce";
}
Optionally, picom can be enabled for nice graphical effects, some example settings:
{
services.picom = {
enable = true;
fade = true;
inactiveOpacity = 0.9;
shadow = true;
fadeDelta = 4;
};
}
Some Xfce programs are not installed automatically. To install them
manually (system wide), put them into your
environment.systemPackages
from pkgs.xfce
.
Thunar (the Xfce file manager) is automatically enabled when Xfce is
enabled. To enable Thunar without enabling Xfce, use the configuration
option programs.thunar.enable
instead of adding
pkgs.xfce.thunar
to environment.systemPackages
.
If you’d like to add extra plugins to Thunar, add them to
programs.thunar.plugins
. You shouldn’t just add them to
environment.systemPackages
.
Even after enabling udisks2, volume management might not work. Thunar
and/or the desktop takes time to show up. Thunar will spit out this kind
of message on start (look at journalctl --user -b
).
Thunar:2410): GVFS-RemoteVolumeMonitor-WARNING **: remote volume monitor with dbus name org.gtk.Private.UDisks2VolumeMonitor is not supported
This is caused by some needed GNOME services not running. This is all fixed by enabling “Launch GNOME services on startup” in the Advanced tab of the Session and Startup settings panel. Alternatively, you can run this command to do the same thing.
$ xfconf-query -c xfce4-session -p /compat/LaunchGNOME -s true
It is necessary to log out and log in again for this to take effect.
Table of Contents
This section describes how to configure networking components on your NixOS machine.
To facilitate network configuration, some desktop environments use NetworkManager. You can enable NetworkManager by setting:
{
networking.networkmanager.enable = true;
}
some desktop managers (e.g., GNOME) enable NetworkManager automatically for you.
All users that should have permission to change network settings must
belong to the networkmanager
group:
{
users.users.alice.extraGroups = [ "networkmanager" ];
}
NetworkManager is controlled using either nmcli
or nmtui
(curses-based terminal user interface). See their manual pages for
details on their usage. Some desktop environments (GNOME, KDE) have
their own configuration tools for NetworkManager. On XFCE, there is no
configuration tool for NetworkManager by default: by enabling
programs.nm-applet.enable
, the graphical applet will be
installed and will launch automatically when the graphical session is
started.
networking.networkmanager
and networking.wireless
(WPA Supplicant)
can be used together if desired. To do this you need to instruct
NetworkManager to ignore those interfaces like:
{
networking.networkmanager.unmanaged = [
"*" "except:type:wwan" "except:type:gsm"
];
}
Refer to the option description for the exact syntax and references to external documentation.
Secure shell (SSH) access to your machine can be enabled by setting:
{
services.openssh.enable = true;
}
By default, root logins using a password are disallowed. They can be
disabled entirely by setting
services.openssh.settings.PermitRootLogin
to "no"
.
You can declaratively specify authorised RSA/DSA public keys for a user as follows:
{
users.users.alice.openssh.authorizedKeys.keys =
[ "ssh-dss AAAAB3NzaC1kc3MAAACBAPIkGWVEt4..." ];
}
By default, NixOS uses DHCP (specifically, dhcpcd
) to automatically
configure network interfaces. However, you can configure an interface
manually as follows:
{
networking.interfaces.eth0.ipv4.addresses = [ {
address = "192.168.1.2";
prefixLength = 24;
} ];
}
Typically you’ll also want to set a default gateway and set of name servers:
{
networking.defaultGateway = "192.168.1.1";
networking.nameservers = [ "8.8.8.8" ];
}
Statically configured interfaces are set up by the systemd service
interface-name-cfg.service
. The default gateway and name server
configuration is performed by network-setup.service
.
The host name is set using networking.hostName
:
{
networking.hostName = "cartman";
}
The default host name is nixos
. Set it to the empty string (""
) to
allow the DHCP server to provide the host name.
IPv6 is enabled by default. Stateless address autoconfiguration is used
to automatically assign IPv6 addresses to all interfaces, and Privacy
Extensions (RFC 4946) are enabled by default. You can adjust the default
for this by setting networking.tempAddresses
. This option
may be overridden on a per-interface basis by
networking.interfaces.<name>.tempAddress
. You can disable
IPv6 support globally by setting:
{
networking.enableIPv6 = false;
}
You can disable IPv6 on a single interface using a normal sysctl (in
this example, we use interface eth0
):
{
boot.kernel.sysctl."net.ipv6.conf.eth0.disable_ipv6" = true;
}
As with IPv4 networking interfaces are automatically configured via DHCPv6. You can configure an interface manually:
{
networking.interfaces.eth0.ipv6.addresses = [ {
address = "fe00:aa:bb:cc::2";
prefixLength = 64;
} ];
}
For configuring a gateway, optionally with explicitly specified interface:
{
networking.defaultGateway6 = {
address = "fe00::1";
interface = "enp0s3";
};
}
See the section called “IPv4 Configuration” for similar examples and additional information.
NixOS has a simple stateful firewall that blocks incoming connections and other unexpected packets. The firewall applies to both IPv4 and IPv6 traffic. It is enabled by default. It can be disabled as follows:
{
networking.firewall.enable = false;
}
If the firewall is enabled, you can open specific TCP ports to the outside world:
{
networking.firewall.allowedTCPPorts = [ 80 443 ];
}
Note that TCP port 22 (ssh) is opened automatically if the SSH daemon is
enabled (services.openssh.enable = true
). UDP ports can be opened through
networking.firewall.allowedUDPPorts
.
To open ranges of TCP ports:
{
networking.firewall.allowedTCPPortRanges = [
{ from = 4000; to = 4007; }
{ from = 8000; to = 8010; }
];
}
Similarly, UDP port ranges can be opened through
networking.firewall.allowedUDPPortRanges
.
For a desktop installation using NetworkManager (e.g., GNOME), you just
have to make sure the user is in the networkmanager
group and you can
skip the rest of this section on wireless networks.
NixOS will start wpa_supplicant for you if you enable this setting:
{
networking.wireless.enable = true;
}
NixOS lets you specify networks for wpa_supplicant declaratively:
{
networking.wireless.networks = {
echelon = { # SSID with no spaces or special characters
psk = "abcdefgh";
};
"echelon's AP" = { # SSID with spaces and/or special characters
psk = "ijklmnop";
};
echelon = { # Hidden SSID
hidden = true;
psk = "qrstuvwx";
};
free.wifi = {}; # Public wireless network
};
}
Be aware that keys will be written to the nix store in plaintext! When
no networks are set, it will default to using a configuration file at
/etc/wpa_supplicant.conf
. You should edit this file yourself to define
wireless networks, WPA keys and so on (see wpa_supplicant.conf(5)).
If you are using WPA2 you can generate pskRaw key using
wpa_passphrase
:
$ wpa_passphrase ESSID PSK
network={
ssid="echelon"
#psk="abcdefgh"
psk=dca6d6ed41f4ab5a984c9f55f6f66d4efdc720ebf66959810f4329bb391c5435
}
{
networking.wireless.networks = {
echelon = {
pskRaw = "dca6d6ed41f4ab5a984c9f55f6f66d4efdc720ebf66959810f4329bb391c5435";
};
};
}
or you can use it to directly generate the wpa_supplicant.conf
:
# wpa_passphrase ESSID PSK > /etc/wpa_supplicant.conf
After you have edited the wpa_supplicant.conf
, you need to restart the
wpa_supplicant service.
# systemctl restart wpa_supplicant.service
You can use networking.localCommands
to
specify shell commands to be run at the end of network-setup.service
. This
is useful for doing network configuration not covered by the existing NixOS
modules. For instance, to statically configure an IPv6 address:
{
networking.localCommands =
''
ip -6 addr add 2001:610:685:1::1/64 dev eth0
'';
}
NixOS uses the udev predictable naming
scheme to assign names
to network interfaces. This means that by default cards are not given
the traditional names like eth0
or eth1
, whose order can change
unpredictably across reboots. Instead, relying on physical locations and
firmware information, the scheme produces names like ens1
, enp2s0
,
etc.
These names are predictable but less memorable and not necessarily
stable: for example installing new hardware or changing firmware
settings can result in a name
change.
If this is undesirable, for example if you have a single ethernet card,
you can revert to the traditional scheme by setting
networking.usePredictableInterfaceNames
to false
.
In case there are multiple interfaces of the same type, it’s better to
assign custom names based on the device hardware address. For example,
we assign the name wan
to the interface with MAC address
52:54:00:12:01:01
using a netword link unit:
{
systemd.network.links."10-wan" = {
matchConfig.PermanentMACAddress = "52:54:00:12:01:01";
linkConfig.Name = "wan";
};
}
Note that links are directly read by udev, not networkd, and will work even if networkd is disabled.
Alternatively, we can use a plain old udev rule:
{
boot.initrd.services.udev.rules = ''
SUBSYSTEM=="net", ACTION=="add", DRIVERS=="?*", \
ATTR{address}=="52:54:00:12:01:01", KERNEL=="eth*", NAME="wan"
'';
}
The rule must be installed in the initrd using
boot.initrd.services.udev.rules
, not the usual services.udev.extraRules
option. This is to avoid race conditions with other programs controlling
the interface.
Table of Contents
You can override the Linux kernel and associated packages using the
option boot.kernelPackages
. For instance, this selects the Linux 3.10
kernel:
{
boot.kernelPackages = pkgs.linuxKernel.packages.linux_3_10;
}
Note that this not only replaces the kernel, but also packages that are specific to the kernel version, such as the NVIDIA video drivers. This ensures that driver packages are consistent with the kernel.
While pkgs.linuxKernel.packages
contains all available kernel packages,
you may want to use one of the unversioned pkgs.linuxPackages_*
aliases
such as pkgs.linuxPackages_latest
, that are kept up to date with new
versions.
Please note that the current convention in NixOS is to only keep actively maintained kernel versions on both unstable and the currently supported stable release(s) of NixOS. This means that a non-longterm kernel will be removed after it’s abandoned by the kernel developers, even on stable NixOS versions. If you pin your kernel onto a non-longterm version, expect your evaluation to fail as soon as the version is out of maintenance.
Longterm versions of kernels will be removed before the next stable NixOS that will exceed the maintenance period of the kernel version.
The default Linux kernel configuration should be fine for most users. You can see the configuration of your current kernel with the following command:
zcat /proc/config.gz
If you want to change the kernel configuration, you can use the
packageOverrides
feature (see the section called “Customising Packages”). For
instance, to enable support for the kernel debugger KGDB:
{
nixpkgs.config.packageOverrides = pkgs: pkgs.lib.recursiveUpdate pkgs {
linuxKernel.kernels.linux_5_10 = pkgs.linuxKernel.kernels.linux_5_10.override {
extraConfig = ''
KGDB y
'';
};
};
}
extraConfig
takes a list of Linux kernel configuration options, one
per line. The name of the option should not include the prefix
CONFIG_
. The option value is typically y
, n
or m
(to build
something as a kernel module).
Kernel modules for hardware devices are generally loaded automatically
by udev
. You can force a module to be loaded via
boot.kernelModules
, e.g.
{
boot.kernelModules = [ "fuse" "kvm-intel" "coretemp" ];
}
If the module is required early during the boot (e.g. to mount the root
file system), you can use boot.initrd.kernelModules
:
{
boot.initrd.kernelModules = [ "cifs" ];
}
This causes the specified modules and their dependencies to be added to the initial ramdisk.
Kernel runtime parameters can be set through
boot.kernel.sysctl
, e.g.
{
boot.kernel.sysctl."net.ipv4.tcp_keepalive_time" = 120;
}
sets the kernel’s TCP keepalive time to 120 seconds. To see the
available parameters, run sysctl -a
.
Please refer to the Nixpkgs manual for the various ways of building a custom kernel.
To use your custom kernel package in your NixOS configuration, set
{
boot.kernelPackages = pkgs.linuxPackagesFor yourCustomKernel;
}
The Linux kernel does not have Rust language support enabled by default. For kernel versions 6.7 or newer, experimental Rust support can be enabled. In a NixOS configuration, set:
{
boot.kernelPatches = [
{
name = "Rust Support";
patch = null;
features = {
rust = true;
};
}
];
}
This section was moved to the Nixpkgs manual.
It’s a common issue that the latest stable version of ZFS doesn’t support the latest
available Linux kernel. It is recommended to use the latest available LTS that’s compatible
with ZFS. Usually this is the default kernel provided by nixpkgs (i.e. pkgs.linuxPackages
).
Alternatively, it’s possible to pin the system to the latest available kernel version that is supported by ZFS like this:
{
boot.kernelPackages = pkgs.zfs.latestCompatibleLinuxPackages;
}
Please note that the version this attribute points to isn’t monotonic because the latest kernel version only refers to kernel versions supported by the Linux developers. In other words, the latest kernel version that ZFS is compatible with may decrease over time.
An example: the latest version ZFS is compatible with is 5.19 which is a non-longterm version. When 5.19 is out of maintenance, the latest supported kernel version is 5.15 because it’s longterm and the versions 5.16, 5.17 and 5.18 are already out of maintenance because they’re non-longterm.
Table of Contents
Subversion is a centralized version-control system. It can use a variety of protocols for communication between client and server.
This section focuses on configuring a web-based server on top of the Apache HTTP server, which uses WebDAV/DeltaV for communication.
For more information on the general setup, please refer to the the appropriate section of the Subversion book.
To configure, include in /etc/nixos/configuration.nix
code to activate
Apache HTTP, setting services.httpd.adminAddr
appropriately:
{
services.httpd.enable = true;
services.httpd.adminAddr = "...";
networking.firewall.allowedTCPPorts = [ 80 443 ];
}
For a simple Subversion server with basic authentication, configure the
Subversion module for Apache as follows, setting hostName
and
documentRoot
appropriately, and SVNParentPath
to the parent
directory of the repositories, AuthzSVNAccessFile
to the location of
the .authz
file describing access permission, and AuthUserFile
to
the password file.
{
services.httpd.extraModules = [
# note that order is *super* important here
{ name = "dav_svn"; path = "${pkgs.apacheHttpdPackages.subversion}/modules/mod_dav_svn.so"; }
{ name = "authz_svn"; path = "${pkgs.apacheHttpdPackages.subversion}/modules/mod_authz_svn.so"; }
];
services.httpd.virtualHosts = {
"svn" = {
hostName = HOSTNAME;
documentRoot = DOCUMENTROOT;
locations."/svn".extraConfig = ''
DAV svn
SVNParentPath REPO_PARENT
AuthzSVNAccessFile ACCESS_FILE
AuthName "SVN Repositories"
AuthType Basic
AuthUserFile PASSWORD_FILE
Require valid-user
'';
};
};
}
The key "svn"
is just a symbolic name identifying the virtual host.
The "/svn"
in locations."/svn".extraConfig
is the path underneath
which the repositories will be served.
This page explains how to set up the Subversion configuration itself. This boils down to the following:
Underneath REPO_PARENT
repositories can be set up as follows:
$ svn create REPO_NAME
Repository files need to be accessible by wwwrun
:
$ chown -R wwwrun:wwwrun REPO_PARENT
The password file PASSWORD_FILE
can be created as follows:
$ htpasswd -cs PASSWORD_FILE USER_NAME
Additional users can be set up similarly, omitting the c
flag:
$ htpasswd -s PASSWORD_FILE USER_NAME
The file describing access permissions ACCESS_FILE
will look something
like the following:
[/]
* = r
[REPO_NAME:/]
USER_NAME = rw
The Subversion repositories will be accessible as
http://HOSTNAME/svn/REPO_NAME
.
Table of Contents
Pantheon is the desktop environment created for the elementary OS distribution. It is written from scratch in Vala, utilizing GNOME technologies with GTK and Granite.
All of Pantheon is working in NixOS and the applications should be available, aside from a few exceptions. To enable Pantheon, set
{
services.xserver.desktopManager.pantheon.enable = true;
}
This automatically enables LightDM and Pantheon’s LightDM greeter. If you’d like to disable this, set
{
services.xserver.displayManager.lightdm.greeters.pantheon.enable = false;
services.xserver.displayManager.lightdm.enable = false;
}
but please be aware using Pantheon without LightDM as a display manager will break screenlocking from the UI. The NixOS module for Pantheon installs all of Pantheon’s default applications. If you’d like to not install Pantheon’s apps, set
{
services.pantheon.apps.enable = false;
}
You can also use environment.pantheon.excludePackages
to remove any other app (like elementary-mail
).
Wingpanel and Switchboard work differently than they do in other distributions, as far as using plugins. You cannot install a plugin globally (like with environment.systemPackages
) to start using it. You should instead be using the following options:
to configure the programs with plugs or indicators.
The difference in NixOS is both these programs are patched to load plugins from a directory that is the value of an environment variable. All of which is controlled in Nix. If you need to configure the particular packages manually you can override the packages like:
wingpanel-with-indicators.override {
indicators = [
pkgs.some-special-indicator
];
}
switchboard-with-plugs.override {
plugs = [
pkgs.some-special-plug
];
}
please note that, like how the NixOS options describe these as extra plugins, this would only add to the default plugins included with the programs. If for some reason you’d like to configure which plugins to use exactly, both packages have an argument for this:
wingpanel-with-indicators.override {
useDefaultIndicators = false;
indicators = specialListOfIndicators;
}
switchboard-with-plugs.override {
useDefaultPlugs = false;
plugs = specialListOfPlugs;
}
this could be most useful for testing a particular plug-in in isolation.
Open Switchboard and go to: Administration → About → Restore Default Settings → Restore Settings. This will reset any dconf settings to their Pantheon defaults. Note this could reset certain GNOME specific preferences if that desktop was used prior.
This is a known issue and there is no known workaround.
AppCenter has been available since 20.03. Starting from 21.11, the Flatpak backend should work so you can install some Flatpak applications using it. However, due to missing appstream metadata, the Packagekit backend does not function currently. See this issue.
If you are using Pantheon, AppCenter should be installed by default if you have Flatpak support enabled. If you also wish to add the appcenter
Flatpak remote:
$ flatpak remote-add --if-not-exists appcenter https://flatpak.elementary.io/repo.flatpakrepo
Table of Contents
GNOME provides a simple, yet full-featured desktop environment with a focus on productivity. Its Mutter compositor supports both Wayland and X server, and the GNOME Shell user interface is fully customizable by extensions.
All of the core apps, optional apps, games, and core developer tools from GNOME are available.
To enable the GNOME desktop use:
{
services.xserver.desktopManager.gnome.enable = true;
services.xserver.displayManager.gdm.enable = true;
}
While it is not strictly necessary to use GDM as the display manager with GNOME, it is recommended, as some features such as screen lock might not work without it.
The default applications used in NixOS are very minimal, inspired by the defaults used in gnome-build-meta.
If you’d like to only use the GNOME desktop and not the apps, you can disable them with:
{
services.gnome.core-utilities.enable = false;
}
and none of them will be installed.
If you’d only like to omit a subset of the core utilities, you can use
environment.gnome.excludePackages
.
Note that this mechanism can only exclude core utilities, games and core developer tools.
It is also possible to disable many of the core services. For example, if you do not need indexing files, you can disable Tracker with:
{
services.gnome.tracker-miners.enable = false;
services.gnome.tracker.enable = false;
}
Note, however, that doing so is not supported and might break some applications. Notably, GNOME Music cannot work without Tracker.
You can install all of the GNOME games with:
{
services.gnome.games.enable = true;
}
You can install GNOME core developer tools with:
{
services.gnome.core-developer-tools.enable = true;
}
GNOME Flashback provides a desktop environment based on the classic GNOME 2 architecture. You can enable the default GNOME Flashback session, which uses the Metacity window manager, with:
{
services.xserver.desktopManager.gnome.flashback.enableMetacity = true;
}
It is also possible to create custom sessions that replace Metacity with a different window manager using services.xserver.desktopManager.gnome.flashback.customSessions
.
The following example uses xmonad
window manager:
{
services.xserver.desktopManager.gnome.flashback.customSessions = [
{
wmName = "xmonad";
wmLabel = "XMonad";
wmCommand = "${pkgs.haskellPackages.xmonad}/bin/xmonad";
enableGnomePanel = false;
}
];
}
Icon themes and GTK themes don’t require any special option to install in NixOS.
You can add them to environment.systemPackages
and switch to them with GNOME Tweaks.
If you’d like to do this manually in dconf, change the values of the following keys:
/org/gnome/desktop/interface/gtk-theme
/org/gnome/desktop/interface/icon-theme
in dconf-editor
Most Shell extensions are packaged under the gnomeExtensions
attribute.
Some packages that include Shell extensions, like gnome.gpaste
, don’t have their extension decoupled under this attribute.
You can install them like any other package:
{
environment.systemPackages = [
gnomeExtensions.dash-to-dock
gnomeExtensions.gsconnect
gnomeExtensions.mpris-indicator-button
];
}
Unfortunately, we lack a way for these to be managed in a completely declarative way.
So you have to enable them manually with an Extensions application.
It is possible to use a GSettings override for this on org.gnome.shell.enabled-extensions
, but that will only influence the default value.
Majority of software building on the GNOME platform use GLib’s GSettings system to manage runtime configuration. For our purposes, the system consists of XML schemas describing the individual configuration options, stored in the package, and a settings backend, where the values of the settings are stored. On NixOS, like on most Linux distributions, dconf database is used as the backend.
GSettings vendor overrides can be used to adjust the default values for settings of the GNOME desktop and apps by replacing the default values specified in the XML schemas. Using overrides will allow you to pre-seed user settings before you even start the session.
Overrides really only change the default values for GSettings keys so if you or an application changes the setting value, the value set by the override will be ignored. Until NixOS’s dconf module implements changing values, you will either need to keep that in mind and clear the setting from the backend using dconf reset
command when that happens, or use the module from home-manager.
You can override the default GSettings values using the
services.xserver.desktopManager.gnome.extraGSettingsOverrides
option.
Take note that whatever packages you want to override GSettings for, you need to add them to
services.xserver.desktopManager.gnome.extraGSettingsOverridePackages
.
You can use dconf-editor
tool to explore which GSettings you can set.
{
services.xserver.desktopManager.gnome = {
extraGSettingsOverrides = ''
# Change default background
[org.gnome.desktop.background]
picture-uri='file://${pkgs.nixos-artwork.wallpapers.mosaic-blue.gnomeFilePath}'
# Favorite apps in gnome-shell
[org.gnome.shell]
favorite-apps=['org.gnome.Console.desktop', 'org.gnome.Nautilus.desktop']
'';
extraGSettingsOverridePackages = [
pkgs.gsettings-desktop-schemas # for org.gnome.desktop
pkgs.gnome.gnome-shell # for org.gnome.shell
];
};
}
Yes you can, and any other display-manager in NixOS.
However, it doesn’t work correctly for the Wayland session of GNOME Shell yet, and won’t be able to lock your screen.
See this issue.
Table of Contents
NixOS has support for several bootloader backends by default: systemd-boot, grub, uboot, etc. The built-in bootloader backend support is generic and supports most use cases. Some users may prefer to create advanced workflows around managing the bootloader and bootable entries.
You can replace the built-in bootloader support with your own tooling using the “external” bootloader option.
Imagine you have created a new package called FooBoot.
FooBoot provides a program at ${pkgs.fooboot}/bin/fooboot-install
which takes the system closure’s path as its only argument and configures the system’s bootloader.
You can enable FooBoot like this:
{ pkgs, ... }: {
boot.loader.external = {
enable = true;
installHook = "${pkgs.fooboot}/bin/fooboot-install";
};
}
Bootloaders should use RFC-0125’s Bootspec format and synthesis tools to identify the key properties for bootable system generations.
Table of Contents
Clevis is a framework for automated decryption of resources. Clevis allows for secure unattended disk decryption during boot, using decryption policies that must be satisfied for the data to decrypt.
The first step is to embed your secret in a JWE file. JWE files have to be created through the clevis command line. 3 types of policies are supported:
TPM policies
Secrets are pinned against the presence of a TPM2 device, for example:
echo -n hi | clevis encrypt tpm2 '{}' > hi.jwe
Tang policies
Secrets are pinned against the presence of a Tang server, for example:
echo -n hi | clevis encrypt tang '{"url": "http://tang.local"}' > hi.jwe
Shamir Secret Sharing
Using Shamir’s Secret Sharing (sss), secrets are pinned using a combination of the two preceding policies. For example:
echo -n hi | clevis encrypt sss \
'{"t": 2, "pins": {"tpm2": {"pcr_ids": "0"}, "tang": {"url": "http://tang.local"}}}' \
> hi.jwe
For more complete documentation on how to generate a secret with clevis, see the clevis documentation.
In order to activate unattended decryption of a resource at boot, enable the clevis
module:
{
boot.initrd.clevis.enable = true;
}
Then, specify the device you want to decrypt using a given clevis secret. Clevis will automatically try to decrypt the device at boot and will fallback to interactive unlocking if the decryption policy is not fulfilled.
{
boot.initrd.clevis.devices."/dev/nvme0n1p1".secretFile = ./nvme0n1p1.jwe;
}
Only bcachefs
, zfs
and luks
encrypted devices are supported at this time.
Table of Contents
Garage
is an open-source, self-hostable S3 store, simpler than MinIO, for geodistributed stores.
The server setup can be automated using
services.garage. A
client configured to your local Garage instance is available in
the global environment as garage-manage
.
The current default by NixOS is garage_0_8
which is also the latest
major version available.
Garage provides a cookbook documentation on how to upgrade: https://garagehq.deuxfleurs.fr/documentation/cookbook/upgrading/
Garage has two types of upgrades: patch-level upgrades and minor/major version upgrades.
In all cases, you should read the changelog and ideally test the upgrade on a staging cluster.
Checking the health of your cluster can be achieved using garage-manage repair
.
Until 1.0 is released, patch-level upgrades are considered as minor version upgrades. Minor version upgrades are considered as major version upgrades. i.e. 0.6 to 0.7 is a major version upgrade.
Straightforward upgrades (patch-level upgrades). Upgrades must be performed one by one, i.e. for each node, stop it, upgrade it : change stateVersion or services.garage.package, restart it if it was not already by switching.
Multiple version upgrades.
Garage do not provide any guarantee on moving more than one major-version forward.
E.g., if you’re on 0.7
, you cannot upgrade to 0.9
.
You need to upgrade to 0.8
first.
As long as stateVersion is declared properly,
this is enforced automatically. The module will issue a warning to remind the user to upgrade to latest
Garage after that deploy.
Here are some baseline instructions to handle advanced upgrades in Garage, when in doubt, please refer to upstream instructions.
Disable API and web access to Garage.
Perform garage-manage repair --all-nodes --yes tables
and garage-manage repair --all-nodes --yes blocks
.
Verify the resulting logs and check that data is synced properly between all nodes.
If you have time, do additional checks (scrub
, block_refs
, etc.).
Check if queues are empty by garage-manage stats
or through monitoring tools.
Run systemctl stop garage
to stop the actual Garage version.
Backup the metadata folder of ALL your nodes, e.g. for a metadata directory (the default one) in /var/lib/garage/meta
,
you can run pushd /var/lib/garage; tar -acf meta-v0.7.tar.zst meta/; popd
.
Run the offline migration: nix-shell -p garage_0_8 --run "garage offline-repair --yes"
, this can take some time depending on how many objects are stored in your cluster.
Bump Garage version in your NixOS configuration, either by changing stateVersion or bumping services.garage.package, this should restart Garage automatically.
Perform garage-manage repair --all-nodes --yes tables
and garage-manage repair --all-nodes --yes blocks
.
Wait for a full table sync to run.
Your upgraded cluster should be in a working state, re-enable API and web access.
As stated in the previous paragraph, we must provide a clean upgrade-path for Garage since it cannot move more than one major version forward on a single upgrade. This chapter adds some notes how Garage updates should be rolled out in the future. This is inspired from how Nextcloud does it.
While patch-level updates are no problem and can be done directly in the
package-expression (and should be backported to supported stable branches after that),
major-releases should be added in a new attribute (e.g. Garage v0.8.0
should be available in nixpkgs
as pkgs.garage_0_8_0
).
To provide simple upgrade paths it’s generally useful to backport those as well to stable
branches. As long as the package-default isn’t altered, this won’t break existing setups.
After that, the versioning-warning in the garage
-module should be
updated to make sure that the
package-option selects the latest version
on fresh setups.
If major-releases will be abandoned by upstream, we should check first if those are needed
in NixOS for a safe upgrade-path before removing those. In that case we should keep those
packages, but mark them as insecure in an expression like this (in
<nixpkgs/pkgs/tools/filesystem/garage/default.nix>
):
/* ... */
{
garage_0_7_3 = generic {
version = "0.7.3";
sha256 = "0000000000000000000000000000000000000000000000000000";
eol = true;
};
}
Ideally we should make sure that it’s possible to jump two NixOS versions forward: i.e. the warnings and the logic in the module should guard a user to upgrade from a Garage on e.g. 22.11 to a Garage on 23.11.
Table of Contents
YouTrack is a browser-based bug tracker, issue tracking system and project management software.
YouTrack exposes a web GUI installer on first login.
You need a token to access it.
You can find this token in the log of the youtrack
service. The log line looks like
* JetBrains YouTrack 2023.3 Configuration Wizard will be available on [http://127.0.0.1:8090/?wizard_token=somelongtoken] after start
Starting with YouTrack 2023.1, JetBrains no longer distributes it as as JAR.
The new distribution with the JetBrains Launcher as a ZIP changed the basic data structure and also some configuration parameters.
Check out https://www.jetbrains.com/help/youtrack/server/YouTrack-Java-Start-Parameters.html for more information on the new configuration options.
When upgrading to YouTrack 2023.1 or higher, a migration script will move the old state directory to /var/lib/youtrack/2022_3
as a backup.
A one-time manual update is required:
Before you update take a backup of your YouTrack instance!
Migrate the options you set in services.youtrack.extraParams
and services.youtrack.jvmOpts
to services.youtrack.generalParameters
and services.youtrack.environmentalParameters
(see the examples and the YouTrack docs)
To start the upgrade set services.youtrack.package = pkgs.youtrack
YouTrack then starts in upgrade mode, meaning you need to obtain the wizard token as above
Select you want to Upgrade YouTrack
As source you select /var/lib/youtrack/2022_3/teamsysdata/
(adopt if you have a different state path)
Change the data directory location to /var/lib/youtrack/data/
. The other paths should already be right.
If you migrate a larger YouTrack instance, it might be useful to set -Dexodus.entityStore.refactoring.forceAll=true
in services.youtrack.generalParameters
for the first startup of YouTrack 2023.x.
Table of Contents
A free and open source manga reader server that runs extensions built for Tachiyomi.
By default, the module will execute Suwayomi-Server backend and web UI:
{ ... }:
{
services.suwayomi-server = {
enable = true;
};
}
It runs in the systemd service named suwayomi-server
in the data directory /var/lib/suwayomi-server
.
You can change the default parameters with some other parameters:
{ ... }:
{
services.suwayomi-server = {
enable = true;
dataDir = "/var/lib/suwayomi"; # Default is "/var/lib/suwayomi-server"
openFirewall = true;
settings = {
server.port = 4567;
};
};
}
If you want to create a desktop icon, you can activate the system tray option:
{ ... }:
{
services.suwayomi-server = {
enable = true;
dataDir = "/var/lib/suwayomi"; # Default is "/var/lib/suwayomi-server"
openFirewall = true;
settings = {
server.port = 4567;
server.enableSystemTray = true;
};
};
}
You can configure a basic authentication to the web interface with:
{ ... }:
{
services.suwayomi-server = {
enable = true;
openFirewall = true;
settings = {
server.port = 4567;
server = {
basicAuthEnabled = true;
basicAuthUsername = "username";
# NOTE: this is not a real upstream option
basicAuthPasswordFile = ./path/to/the/password/file;
};
};
};
}
Not all the configuration options are available directly in this module, but you can add the other options of suwayomi-server with:
{ ... }:
{
services.suwayomi-server = {
enable = true;
openFirewall = true;
settings = {
server = {
port = 4567;
autoDownloadNewChapters = false;
maxSourcesInParallel = 6;
extensionRepos = [
"https://raw.githubusercontent.com/MY_ACCOUNT/MY_REPO/repo/index.min.json"
];
};
};
};
}
Table of Contents
Plausible is a privacy-friendly alternative to Google analytics.
At first, a secret key is needed to be generated. This can be done with e.g.
$ openssl rand -base64 64
After that, plausible
can be deployed like this:
{
services.plausible = {
enable = true;
adminUser = {
# activate is used to skip the email verification of the admin-user that's
# automatically created by plausible. This is only supported if
# postgresql is configured by the module. This is done by default, but
# can be turned off with services.plausible.database.postgres.setup.
activate = true;
email = "admin@localhost";
passwordFile = "/run/secrets/plausible-admin-pwd";
};
server = {
baseUrl = "http://analytics.example.org";
# secretKeybaseFile is a path to the file which contains the secret generated
# with openssl as described above.
secretKeybaseFile = "/run/secrets/plausible-secret-key-base";
};
};
}
Table of Contents
pict-rs is a a simple image hosting service.
the minimum to start pict-rs is
{
services.pict-rs.enable = true;
}
this will start the http server on port 8080 by default.
pict-rs offers the following endpoints:
POST /image
for uploading an image. Uploaded content must be valid multipart/form-data with an
image array located within the images[]
key
This endpoint returns the following JSON structure on success with a 201 Created status
{
"files": [
{
"delete_token": "JFvFhqJA98",
"file": "lkWZDRvugm.jpg"
},
{
"delete_token": "kAYy9nk2WK",
"file": "8qFS0QooAn.jpg"
},
{
"delete_token": "OxRpM3sf0Y",
"file": "1hJaYfGE01.jpg"
}
],
"msg": "ok"
}
GET /image/download?url=...
Download an image from a remote server, returning the same JSON
payload as the POST
endpoint
GET /image/original/{file}
for getting a full-resolution image. file
here is the file
key from the
/image
endpoint’s JSON
GET /image/details/original/{file}
for getting the details of a full-resolution image.
The returned JSON is structured like so:
{
"width": 800,
"height": 537,
"content_type": "image/webp",
"created_at": [
2020,
345,
67376,
394363487
]
}
GET /image/process.{ext}?src={file}&...
get a file with transformations applied.
existing transformations include
identity=true
: apply no changes
blur={float}
: apply a gaussian blur to the file
thumbnail={int}
: produce a thumbnail of the image fitting inside an {int}
by {int}
square using raw pixel sampling
resize={int}
: produce a thumbnail of the image fitting inside an {int}
by {int}
square
using a Lanczos2 filter. This is slower than sampling but looks a bit better in some cases
crop={int-w}x{int-h}
: produce a cropped version of the image with an {int-w}
by {int-h}
aspect ratio. The resulting crop will be centered on the image. Either the width or height
of the image will remain full-size, depending on the image’s aspect ratio and the requested
aspect ratio. For example, a 1600x900 image cropped with a 1x1 aspect ratio will become 900x900. A
1600x1100 image cropped with a 16x9 aspect ratio will become 1600x900.
Supported ext
file extensions include png
, jpg
, and webp
An example of usage could be
GET /image/process.jpg?src=asdf.png&thumbnail=256&blur=3.0
which would create a 256x256px JPEG thumbnail and blur it
GET /image/details/process.{ext}?src={file}&...
for getting the details of a processed image.
The returned JSON is the same format as listed for the full-resolution details endpoint.
DELETE /image/delete/{delete_token}/{file}
or GET /image/delete/{delete_token}/{file}
to
delete a file, where delete_token
and file
are from the /image
endpoint’s JSON
Configuring the secure-api-key is not included yet. The envisioned basic use case is consumption on localhost by other services without exposing the service to the internet.
Table of Contents
Nextcloud is an open-source,
self-hostable cloud platform. The server setup can be automated using
services.nextcloud. A
desktop client is packaged at pkgs.nextcloud-client
.
The current default by NixOS is nextcloud29
which is also the latest
major version available.
Nextcloud is a PHP-based application which requires an HTTP server
(services.nextcloud
and optionally supports
services.nginx
).
For the database, you can set
services.nextcloud.config.dbtype
to
either sqlite
(the default), mysql
, or pgsql
. The simplest is sqlite
,
which will be automatically created and managed by the application. For the
last two, you can easily create a local database by setting
services.nextcloud.database.createLocally
to true
, Nextcloud will automatically be configured to connect to it through
socket.
A very basic configuration may look like this:
{ pkgs, ... }:
{
services.nextcloud = {
enable = true;
hostName = "nextcloud.tld";
database.createLocally = true;
config = {
dbtype = "pgsql";
adminpassFile = "/path/to/admin-pass-file";
};
};
networking.firewall.allowedTCPPorts = [ 80 443 ];
}
The hostName
option is used internally to configure an HTTP
server using PHP-FPM
and nginx
. The config
attribute set is
used by the imperative installer and all values are written to an additional file
to ensure that changes can be applied by changing the module’s options.
In case the application serves multiple domains (those are checked with
$_SERVER['HTTP_HOST']
)
it’s needed to add them to
services.nextcloud.settings.trusted_domains
.
Auto updates for Nextcloud apps can be enabled using
services.nextcloud.autoUpdateApps
.
General notes.
Unfortunately Nextcloud appears to be very stateful when it comes to
managing its own configuration. The config file lives in the home directory
of the nextcloud
user (by default
/var/lib/nextcloud/config/config.php
) and is also used to
track several states of the application (e.g., whether installed or not).
All configuration parameters are also stored in
/var/lib/nextcloud/config/override.config.php
which is generated by
the module and linked from the store to ensure that all values from
config.php
can be modified by the module.
However config.php
manages the application’s state and shouldn’t be
touched manually because of that.
Don’t delete config.php
! This file
tracks the application’s state and a deletion can cause unwanted
side-effects!
Don’t rerun nextcloud-occ maintenance:install
!
This command tries to install the application
and can cause unwanted side-effects!
Multiple version upgrades.
Nextcloud doesn’t allow to move more than one major-version forward. E.g., if you’re on
v16
, you cannot upgrade to v18
, you need to upgrade to
v17
first. This is ensured automatically as long as the
stateVersion is declared properly. In that case
the oldest version available (one major behind the one from the previous NixOS
release) will be selected by default and the module will generate a warning that reminds
the user to upgrade to latest Nextcloud after that deploy.
Error: Command "upgrade" is not defined.
This error usually occurs if the initial installation
(nextcloud-occ maintenance:install) has failed. After that, the application
is not installed, but the upgrade is attempted to be executed. Further context can
be found in NixOS/nixpkgs#111175.
First of all, it makes sense to find out what went wrong by looking at the logs of the installation via journalctl -u nextcloud-setup and try to fix the underlying issue.
If this occurs on an existing setup, this is most likely because the maintenance mode is active. It can be deactivated by running nextcloud-occ maintenance:mode --off. It’s advisable though to check the logs first on why the maintenance mode was activated.
Only perform the following measures on freshly installed instances!
A re-run of the installer can be forced by deleting
/var/lib/nextcloud/config/config.php
. This is the only time
advisable because the fresh install doesn’t have any state that can be lost.
In case that doesn’t help, an entire re-creation can be forced via
rm -rf ~nextcloud/.
Server-side encryption. Nextcloud supports server-side encryption (SSE). This is not an end-to-end encryption, but can be used to encrypt files that will be persisted to external storage such as S3.
httpd
) By default, nginx
is used as reverse-proxy for nextcloud
.
However, it’s possible to use e.g. httpd
by explicitly disabling
nginx
using services.nginx.enable
and fixing the
settings listen.owner
& listen.group
in the
corresponding phpfpm
pool.
An exemplary configuration may look like this:
{ config, lib, pkgs, ... }: {
services.nginx.enable = false;
services.nextcloud = {
enable = true;
hostName = "localhost";
/* further, required options */
};
services.phpfpm.pools.nextcloud.settings = {
"listen.owner" = config.services.httpd.user;
"listen.group" = config.services.httpd.group;
};
services.httpd = {
enable = true;
adminAddr = "webmaster@localhost";
extraModules = [ "proxy_fcgi" ];
virtualHosts."localhost" = {
documentRoot = config.services.nextcloud.package;
extraConfig = ''
<Directory "${config.services.nextcloud.package}">
<FilesMatch "\.php$">
<If "-f %{REQUEST_FILENAME}">
SetHandler "proxy:unix:${config.services.phpfpm.pools.nextcloud.socket}|fcgi://localhost/"
</If>
</FilesMatch>
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /
RewriteRule ^index\.php$ - [L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /index.php [L]
</IfModule>
DirectoryIndex index.php
Require all granted
Options +FollowSymLinks
</Directory>
'';
};
};
}
Nextcloud apps are installed statefully through the web interface.
Some apps may require extra PHP extensions to be installed.
This can be configured with the services.nextcloud.phpExtraExtensions
setting.
Alternatively, extra apps can also be declared with the services.nextcloud.extraApps
setting.
When using this setting, apps can no longer be managed statefully because this can lead to Nextcloud updating apps
that are managed by Nix. If you want automatic updates it is recommended that you use web interface to install apps.
This is because
our module writes logs into the journal (journalctl -t Nextcloud
)
the Logreader application that allows reading logs in the admin panel is enabled by default and requires logs written to a file.
The logreader application doesn’t work, as it was the case before. The only change is that it complains loudly now. So nothing actionable here by default. Alternatively you can
disable the logreader application to shut up the “error”.
We can’t really do that by default since whether apps are enabled/disabled is part of the application’s state and tracked inside the database.
set services.nextcloud.settings.log_type
to “file” to be able to view logs
from the admin panel.
As stated in the previous paragraph, we must provide a clean upgrade-path for Nextcloud since it cannot move more than one major version forward on a single upgrade. This chapter adds some notes how Nextcloud updates should be rolled out in the future.
While minor and patch-level updates are no problem and can be done directly in the
package-expression (and should be backported to supported stable branches after that),
major-releases should be added in a new attribute (e.g. Nextcloud v19.0.0
should be available in nixpkgs
as pkgs.nextcloud19
).
To provide simple upgrade paths it’s generally useful to backport those as well to stable
branches. As long as the package-default isn’t altered, this won’t break existing setups.
After that, the versioning-warning in the nextcloud
-module should be
updated to make sure that the
package-option selects the latest version
on fresh setups.
If major-releases will be abandoned by upstream, we should check first if those are needed
in NixOS for a safe upgrade-path before removing those. In that case we should keep those
packages, but mark them as insecure in an expression like this (in
<nixpkgs/pkgs/servers/nextcloud/default.nix>
):
/* ... */
{
nextcloud17 = generic {
version = "17.0.x";
sha256 = "0000000000000000000000000000000000000000000000000000";
eol = true;
};
}
Ideally we should make sure that it’s possible to jump two NixOS versions forward: i.e. the warnings and the logic in the module should guard a user to upgrade from a Nextcloud on e.g. 19.09 to a Nextcloud on 20.09.
Table of Contents
Matomo is a real-time web analytics application. This module configures php-fpm as backend for Matomo, optionally configuring an nginx vhost as well.
An automatic setup is not supported by Matomo, so you need to configure Matomo itself in the browser-based Matomo setup.
You also need to configure a MariaDB or MySQL database and -user for Matomo yourself, and enter those credentials in your browser. You can use passwordless database authentication via the UNIX_SOCKET authentication plugin with the following SQL commands:
# For MariaDB
INSTALL PLUGIN unix_socket SONAME 'auth_socket';
CREATE DATABASE matomo;
CREATE USER 'matomo'@'localhost' IDENTIFIED WITH unix_socket;
GRANT ALL PRIVILEGES ON matomo.* TO 'matomo'@'localhost';
# For MySQL
INSTALL PLUGIN auth_socket SONAME 'auth_socket.so';
CREATE DATABASE matomo;
CREATE USER 'matomo'@'localhost' IDENTIFIED WITH auth_socket;
GRANT ALL PRIVILEGES ON matomo.* TO 'matomo'@'localhost';
Then fill in matomo
as database user and database name,
and leave the password field blank. This authentication works by allowing
only the matomo
unix user to authenticate as the
matomo
database user (without needing a password), but no
other users. For more information on passwordless login, see
https://mariadb.com/kb/en/mariadb/unix_socket-authentication-plugin/.
Of course, you can use password based authentication as well, e.g. when the database is not on the same host.
This module comes with the systemd service
matomo-archive-processing.service
and a timer that
automatically triggers archive processing every hour. This means that you
can safely
disable browser triggers for Matomo archiving at
Administration > System > General Settings
.
With automatic archive processing, you can now also enable to
delete old visitor logs
at Administration > System > Privacy
, but make sure that you run systemctl start matomo-archive-processing.service
at least once without errors if
you have already collected data before, so that the reports get archived
before the source data gets deleted.
You only need to take backups of your MySQL database and the
/var/lib/matomo/config/config.ini.php
file. Use a user
in the matomo
group or root to access the file. For more
information, see
https://matomo.org/faq/how-to-install/faq_138/.
Matomo will warn you that the JavaScript tracker is not writable. This is because it’s located in the read-only nix store. You can safely ignore this, unless you need a plugin that needs JavaScript tracker access.
You can use other web servers by forwarding calls for
index.php
and piwik.php
to the
services.phpfpm.pools.<name>.socket
fastcgi unix socket. You can use
the nginx configuration in the module code as a reference to what else
should be configured.
Table of Contents
Lemmy is a federated alternative to reddit in rust.
the minimum to start lemmy is
{
services.lemmy = {
enable = true;
settings = {
hostname = "lemmy.union.rocks";
database.createLocally = true;
};
caddy.enable = true;
};
}
this will start the backend on port 8536 and the frontend on port 1234. It will expose your instance with a caddy reverse proxy to the hostname you’ve provided. Postgres will be initialized on that same instance automatically.
On first connection you will be asked to define an admin user.
Exposing with nginx is not implemented yet.
This has been tested using a local database with a unix socket connection. Using different database settings will likely require modifications
Table of Contents
Keycloak is an open source identity and access management server with support for OpenID Connect, OAUTH 2.0 and SAML 2.0.
An administrative user with the username
admin
is automatically created in the
master
realm. Its initial password can be
configured by setting services.keycloak.initialAdminPassword
and defaults to changeme
. The password is
not stored safely and should be changed immediately in the
admin panel.
Refer to the Keycloak Server Administration Guide for information on how to administer your Keycloak instance.
Keycloak can be used with either PostgreSQL, MariaDB or
MySQL. Which one is used can be
configured in services.keycloak.database.type
. The selected
database will automatically be enabled and a database and role
created unless services.keycloak.database.host
is changed
from its default of localhost
or
services.keycloak.database.createLocally
is set to false
.
External database access can also be configured by setting
services.keycloak.database.host
,
services.keycloak.database.name
,
services.keycloak.database.username
,
services.keycloak.database.useSSL
and
services.keycloak.database.caCert
as
appropriate. Note that you need to manually create the database
and allow the configured database user full access to it.
services.keycloak.database.passwordFile
must be set to the path to a file containing the password used
to log in to the database. If services.keycloak.database.host
and services.keycloak.database.createLocally
are kept at their defaults, the database role
keycloak
with that password is provisioned
on the local database instance.
The path should be provided as a string, not a Nix path, since Nix paths are copied into the world readable Nix store.
The hostname is used to build the public URL used as base for
all frontend requests and must be configured through
services.keycloak.settings.hostname
.
If you’re migrating an old Wildfly based Keycloak instance
and want to keep compatibility with your current clients,
you’ll likely want to set services.keycloak.settings.http-relative-path
to /auth
. See the option description
for more details.
services.keycloak.settings.hostname-strict-backchannel
determines whether Keycloak should force all requests to go
through the frontend URL. By default,
Keycloak allows backend requests to
instead use its local hostname or IP address and may also
advertise it to clients through its OpenID Connect Discovery
endpoint.
For more information on hostname configuration, see the Hostname section of the Keycloak Server Installation and Configuration Guide.
By default, Keycloak won’t accept unsecured HTTP connections originating from outside its local network.
HTTPS support requires a TLS/SSL certificate and a private key,
both PEM formatted.
Their paths should be set through
services.keycloak.sslCertificate
and
services.keycloak.sslCertificateKey
.
The paths should be provided as a strings, not a Nix paths, since Nix paths are copied into the world readable Nix store.
You can package custom themes and make them visible to
Keycloak through services.keycloak.themes
. See the
Themes section of the Keycloak Server Development Guide and the description of the aforementioned NixOS option for
more information.
Keycloak server configuration parameters can be set in
services.keycloak.settings
. These correspond
directly to options in
conf/keycloak.conf
. Some of the most
important parameters are documented as suboptions, the rest can
be found in the All
configuration section of the Keycloak Server Installation and
Configuration Guide.
Options containing secret data should be set to an attribute
set containing the attribute _secret
- a
string pointing to a file containing the value the option
should be set to. See the description of
services.keycloak.settings
for an example.
A basic configuration with some custom settings could look like this:
{
services.keycloak = {
enable = true;
settings = {
hostname = "keycloak.example.com";
hostname-strict-backchannel = true;
};
initialAdminPassword = "e6Wcm0RrtegMEHl"; # change on first login
sslCertificate = "/run/keys/ssl_cert";
sslCertificateKey = "/run/keys/ssl_key";
database.passwordFile = "/run/keys/db_password";
};
}
Table of Contents
With Jitsi Meet on NixOS you can quickly configure a complete, private, self-hosted video conferencing solution.
A minimal configuration using Let’s Encrypt for TLS certificates looks like this:
{
services.jitsi-meet = {
enable = true;
hostName = "jitsi.example.com";
};
services.jitsi-videobridge.openFirewall = true;
networking.firewall.allowedTCPPorts = [ 80 443 ];
security.acme.email = "me@example.com";
security.acme.acceptTerms = true;
}
Here is the minimal configuration with additional configurations:
{
services.jitsi-meet = {
enable = true;
hostName = "jitsi.example.com";
config = {
enableWelcomePage = false;
prejoinPageEnabled = true;
defaultLang = "fi";
};
interfaceConfig = {
SHOW_JITSI_WATERMARK = false;
SHOW_WATERMARK_FOR_GUESTS = false;
};
};
services.jitsi-videobridge.openFirewall = true;
networking.firewall.allowedTCPPorts = [ 80 443 ];
security.acme.email = "me@example.com";
security.acme.acceptTerms = true;
}
Table of Contents
With Honk on NixOS you can quickly configure a complete ActivityPub server with minimal setup and support costs.
A minimal configuration looks like this:
{
services.honk = {
enable = true;
host = "0.0.0.0";
port = 8080;
username = "username";
passwordFile = "/etc/honk/password.txt";
servername = "honk.example.com";
};
networking.firewall.allowedTCPPorts = [ 8080 ];
}
Table of Contents
Grocy is a web-based self-hosted groceries & household management solution for your home.
A very basic configuration may look like this:
{ pkgs, ... }:
{
services.grocy = {
enable = true;
hostName = "grocy.tld";
};
}
This configures a simple vhost using nginx
which listens to grocy.tld
with fully configured ACME/LE (this can be
disabled by setting services.grocy.nginx.enableSSL
to false
). After the initial setup the credentials admin:admin
can be used to login.
The application’s state is persisted at /var/lib/grocy/grocy.db
in a
sqlite3
database. The migration is applied when requesting the /
-route
of the application.
The configuration for grocy
is located at /etc/grocy/config.php
.
By default, the following settings can be defined in the NixOS-configuration:
{ pkgs, ... }:
{
services.grocy.settings = {
# The default currency in the system for invoices etc.
# Please note that exchange rates aren't taken into account, this
# is just the setting for what's shown in the frontend.
currency = "EUR";
# The display language (and locale configuration) for grocy.
culture = "de";
calendar = {
# Whether or not to show the week-numbers
# in the calendar.
showWeekNumber = true;
# Index of the first day to be shown in the calendar (0=Sunday, 1=Monday,
# 2=Tuesday and so on).
firstDayOfWeek = 2;
};
};
}
If you want to alter the configuration file on your own, you can do this manually with an expression like this:
{ lib, ... }:
{
environment.etc."grocy/config.php".text = lib.mkAfter ''
// Arbitrary PHP code in grocy's configuration file
'';
}
Table of Contents
GoToSocial is an ActivityPub social network server, written in Golang.
The following configuration sets up the PostgreSQL as database backend and binds
GoToSocial to 127.0.0.1:8080
, expecting to be run behind a HTTP proxy on gotosocial.example.com
.
{
services.gotosocial = {
enable = true;
setupPostgresqlDB = true;
settings = {
application-name = "My GoToSocial";
host = "gotosocial.example.com";
protocol = "https";
bind-address = "127.0.0.1";
port = 8080;
};
};
}
Please refer to the GoToSocial Documentation for additional configuration options.
Although it is possible to expose GoToSocial directly, it is common practice to operate it behind an HTTP reverse proxy such as nginx.
{
networking.firewall.allowedTCPPorts = [ 80 443 ];
services.nginx = {
enable = true;
clientMaxBodySize = "40M";
virtualHosts = with config.services.gotosocial.settings; {
"${host}" = {
enableACME = true;
forceSSL = true;
locations = {
"/" = {
recommendedProxySettings = true;
proxyWebsockets = true;
proxyPass = "http://${bind-address}:${toString port}";
};
};
};
};
};
}
Please refer to SSL/TLS Certificates with ACME for details on how to provision an SSL/TLS certificate.
After the GoToSocial service is running, the gotosocial-admin
utility can be used to manage users. In particular an
administrative user can be created with
$ sudo gotosocial-admin account create --username <nickname> --email <email> --password <password>
$ sudo gotosocial-admin account confirm --username <nickname>
$ sudo gotosocial-admin account promote --username <nickname>
Table of Contents
FileSender is a software that makes it easy to send and receive big files.
FileSender uses SimpleSAMLphp for authentication, which needs to be configured separately.
Minimal working instance of FileSender that uses password-authentication would look like this:
{
networking.firewall.allowedTCPPorts = [ 80 443 ];
services.filesender = {
enable = true;
localDomain = "filesender.example.com";
configureNginx = true;
database.createLocally = true;
settings = {
auth_sp_saml_authentication_source = "default";
auth_sp_saml_uid_attribute = "uid";
storage_filesystem_path = "<STORAGE PATH FOR UPLOADED FILES>";
admin = "admin";
admin_email = "admin@example.com";
email_reply_to = "noreply@example.com";
};
};
services.simplesamlphp.filesender = {
settings = {
"module.enable".exampleauth = true;
};
authSources = {
admin = [ "core:AdminPassword" ];
default = format.lib.mkMixedArray [ "exampleauth:UserPass" ] {
"admin:admin123" = {
uid = [ "admin" ];
cn = [ "admin" ];
mail = [ "admin@example.com" ];
};
};
};
};
}
Example above uses hardcoded clear-text password, in production you should use other authentication method like LDAP. You can check supported authentication methods in SimpleSAMLphp documentation.
Table of Contents
Discourse is a modern and open source discussion platform.
A minimal configuration using Let’s Encrypt for TLS certificates looks like this:
{
services.discourse = {
enable = true;
hostname = "discourse.example.com";
admin = {
email = "admin@example.com";
username = "admin";
fullName = "Administrator";
passwordFile = "/path/to/password_file";
};
secretKeyBaseFile = "/path/to/secret_key_base_file";
};
security.acme.email = "me@example.com";
security.acme.acceptTerms = true;
}
Provided a proper DNS setup, you’ll be able to connect to the
instance at discourse.example.com
and log in
using the credentials provided in
services.discourse.admin
.
To set up TLS using a regular certificate and key on file, use
the services.discourse.sslCertificate
and services.discourse.sslCertificateKey
options:
{
services.discourse = {
enable = true;
hostname = "discourse.example.com";
sslCertificate = "/path/to/ssl_certificate";
sslCertificateKey = "/path/to/ssl_certificate_key";
admin = {
email = "admin@example.com";
username = "admin";
fullName = "Administrator";
passwordFile = "/path/to/password_file";
};
secretKeyBaseFile = "/path/to/secret_key_base_file";
};
}
Discourse uses PostgreSQL to store most of its
data. A database will automatically be enabled and a database
and role created unless services.discourse.database.host
is changed from
its default of null
or services.discourse.database.createLocally
is set
to false
.
External database access can also be configured by setting
services.discourse.database.host
,
services.discourse.database.username
and
services.discourse.database.passwordFile
as
appropriate. Note that you need to manually create a database
called discourse
(or the name you chose in
services.discourse.database.name
) and
allow the configured database user full access to it.
In addition to the basic setup, you’ll want to configure an SMTP server Discourse can use to send user registration and password reset emails, among others. You can also optionally let Discourse receive email, which enables people to reply to threads and conversations via email.
A basic setup which assumes you want to use your configured hostname as email domain can be done like this:
{
services.discourse = {
enable = true;
hostname = "discourse.example.com";
sslCertificate = "/path/to/ssl_certificate";
sslCertificateKey = "/path/to/ssl_certificate_key";
admin = {
email = "admin@example.com";
username = "admin";
fullName = "Administrator";
passwordFile = "/path/to/password_file";
};
mail.outgoing = {
serverAddress = "smtp.emailprovider.com";
port = 587;
username = "user@emailprovider.com";
passwordFile = "/path/to/smtp_password_file";
};
mail.incoming.enable = true;
secretKeyBaseFile = "/path/to/secret_key_base_file";
};
}
This assumes you have set up an MX record for the address you’ve set in hostname and requires proper SPF, DKIM and DMARC configuration to be done for the domain you’re sending from, in order for email to be reliably delivered.
If you want to use a different domain for your outgoing email
(for example example.com
instead of
discourse.example.com
) you should set
services.discourse.mail.notificationEmailAddress
and
services.discourse.mail.contactEmailAddress
manually.
Setup of TLS for incoming email is currently only configured
automatically when a regular TLS certificate is used, i.e. when
services.discourse.sslCertificate
and
services.discourse.sslCertificateKey
are
set.
Additional site settings and backend settings, for which no
explicit NixOS options are provided,
can be set in services.discourse.siteSettings
and
services.discourse.backendSettings
respectively.
“Site settings” are the settings that can be
changed through the Discourse
UI. Their default values can be set using
services.discourse.siteSettings
.
Settings are expressed as a Nix attribute set which matches the
structure of the configuration in
config/site_settings.yml.
To find a setting’s path, you only need to care about the first
two levels; i.e. its category (e.g. login
)
and name (e.g. invite_only
).
Settings containing secret data should be set to an attribute
set containing the attribute _secret
- a
string pointing to a file containing the value the option
should be set to. See the example.
Settings are expressed as a Nix attribute set which matches the
structure of the configuration in
config/discourse.conf.
Empty parameters can be defined by setting them to
null
.
The following example sets the title and description of the Discourse instance and enables GitHub login in the site settings, and changes a few request limits in the backend settings:
{
services.discourse = {
enable = true;
hostname = "discourse.example.com";
sslCertificate = "/path/to/ssl_certificate";
sslCertificateKey = "/path/to/ssl_certificate_key";
admin = {
email = "admin@example.com";
username = "admin";
fullName = "Administrator";
passwordFile = "/path/to/password_file";
};
mail.outgoing = {
serverAddress = "smtp.emailprovider.com";
port = 587;
username = "user@emailprovider.com";
passwordFile = "/path/to/smtp_password_file";
};
mail.incoming.enable = true;
siteSettings = {
required = {
title = "My Cats";
site_description = "Discuss My Cats (and be nice plz)";
};
login = {
enable_github_logins = true;
github_client_id = "a2f6dfe838cb3206ce20";
github_client_secret._secret = /run/keys/discourse_github_client_secret;
};
};
backendSettings = {
max_reqs_per_ip_per_minute = 300;
max_reqs_per_ip_per_10_seconds = 60;
max_asset_reqs_per_ip_per_10_seconds = 250;
max_reqs_per_ip_mode = "warn+block";
};
secretKeyBaseFile = "/path/to/secret_key_base_file";
};
}
In the resulting site settings file, the
login.github_client_secret
key will be set
to the contents of the
/run/keys/discourse_github_client_secret
file.
You can install Discourse plugins
using the services.discourse.plugins
option. Pre-packaged plugins are provided in
<your_discourse_package_here>.plugins
. If
you want the full suite of plugins provided through
nixpkgs
, you can also set the services.discourse.package
option to
pkgs.discourseAllPlugins
.
Plugins can be built with the
<your_discourse_package_here>.mkDiscoursePlugin
function. Normally, it should suffice to provide a
name
and src
attribute. If
the plugin has Ruby dependencies, however, they need to be
packaged in accordance with the Developing with Ruby
section of the Nixpkgs manual and the
appropriate gem options set in bundlerEnvArgs
(normally gemdir
is sufficient). A plugin’s
Ruby dependencies are listed in its
plugin.rb
file as function calls to
gem
. To construct the corresponding
Gemfile
manually, run bundle init, then add the gem
lines to it
verbatim.
Much of the packaging can be done automatically by the
nixpkgs/pkgs/servers/web-apps/discourse/update.py
script - just add the plugin to the plugins
list in the update_plugins
function and run
the script:
./update.py update-plugins
Some plugins provide site settings.
Their defaults can be configured using services.discourse.siteSettings
, just like
regular site settings. To find the names of these settings, look
in the config/settings.yml
file of the plugin
repo.
For example, to add the discourse-spoiler-alert
and discourse-solved
plugins, and disable discourse-spoiler-alert
by default:
{
services.discourse = {
enable = true;
hostname = "discourse.example.com";
sslCertificate = "/path/to/ssl_certificate";
sslCertificateKey = "/path/to/ssl_certificate_key";
admin = {
email = "admin@example.com";
username = "admin";
fullName = "Administrator";
passwordFile = "/path/to/password_file";
};
mail.outgoing = {
serverAddress = "smtp.emailprovider.com";
port = 587;
username = "user@emailprovider.com";
passwordFile = "/path/to/smtp_password_file";
};
mail.incoming.enable = true;
plugins = with config.services.discourse.package.plugins; [
discourse-spoiler-alert
discourse-solved
];
siteSettings = {
plugins = {
spoiler_enabled = false;
};
};
secretKeyBaseFile = "/path/to/secret_key_base_file";
};
}
Table of Contents
Davis is a caldav and carrddav server. It has a simple, fully translatable admin interface for sabre/dav based on Symfony 5 and Bootstrap 5, initially inspired by Baïkal.
At first, an application secret is needed, this can be generated with:
$ cat /dev/urandom | tr -dc a-zA-Z0-9 | fold -w 48 | head -n 1
After that, davis
can be deployed like this:
{
services.davis = {
enable = true;
hostname = "davis.example.com";
mail = {
dsn = "smtp://username@example.com:25";
inviteFromAddress = "davis@example.com";
};
adminLogin = "admin";
adminPasswordFile = "/run/secrets/davis-admin-password";
appSecretFile = "/run/secrets/davis-app-secret";
nginx = {};
};
}
This deploys Davis using a sqlite database running out of /var/lib/davis
.
Table of Contents
Castopod is an open-source hosting platform made for podcasters who want to engage and interact with their audience.
Configure ACME (https://nixos.org/manual/nixos/unstable/#module-security-acme).
Use the following configuration to start a public instance of Castopod on castopod.example.com
domain:
{
networking.firewall.allowedTCPPorts = [ 80 443 ];
services.castopod = {
enable = true;
database.createLocally = true;
nginx.virtualHost = {
serverName = "castopod.example.com";
enableACME = true;
forceSSL = true;
};
};
}
Go to https://castopod.example.com/cp-install
to create superadmin account after applying the above configuration.
c2FmZQ is an application that can securely encrypt, store, and share files, including but not limited to pictures and videos.
The service c2fmzq-server
can be enabled by setting
{
services.c2fmzq-server.enable = true;
}
This will spin up an instance of the server which is API-compatible with Stingle Photos and an experimental Progressive Web App (PWA) to interact with the storage via the browser.
In principle the server can be exposed directly on a public interface and there are command line options to manage HTTPS certificates directly, but the module is designed to be served behind a reverse proxy or only accessed via localhost.
{
services.c2fmzq-server = {
enable = true;
bindIP = "127.0.0.1"; # default
port = 8080; # default
};
services.nginx = {
enable = true;
recommendedProxySettings = true;
virtualHosts."example.com" = {
enableACME = true;
forceSSL = true;
locations."/" = {
proxyPass = "http://127.0.0.1:8080";
};
};
};
}
For more information, see https://github.com/c2FmZQ/c2FmZQ/.
Table of Contents
Akkoma is a lightweight ActivityPub microblogging server forked from Pleroma.
The Elixir configuration file required by Akkoma is generated automatically from
services.akkoma.config
. Secrets must be
included from external files outside of the Nix store by setting the configuration option to
an attribute set containing the attribute _secret
– a string pointing to the file
containing the actual value of the option.
For the mandatory configuration settings these secrets will be generated automatically if the
referenced file does not exist during startup, unless disabled through
services.akkoma.initSecrets
.
The following configuration binds Akkoma to the Unix socket /run/akkoma/socket
, expecting to
be run behind a HTTP proxy on fediverse.example.com
.
{
services.akkoma.enable = true;
services.akkoma.config = {
":pleroma" = {
":instance" = {
name = "My Akkoma instance";
description = "More detailed description";
email = "admin@example.com";
registration_open = false;
};
"Pleroma.Web.Endpoint" = {
url.host = "fediverse.example.com";
};
};
};
}
Please refer to the configuration cheat sheet for additional configuration options.
After the Akkoma service is running, the administration utility can be used to manage users. In particular an administrative user can be created with
$ pleroma_ctl user new <nickname> <email> --admin --moderator --password <password>
Although it is possible to expose Akkoma directly, it is common practice to operate it behind an HTTP reverse proxy such as nginx.
{
services.akkoma.nginx = {
enableACME = true;
forceSSL = true;
};
services.nginx = {
enable = true;
clientMaxBodySize = "16m";
recommendedTlsSettings = true;
recommendedOptimisation = true;
recommendedGzipSettings = true;
};
}
Please refer to SSL/TLS Certificates with ACME for details on how to provision an SSL/TLS certificate.
Without the media proxy function, Akkoma does not store any remote media like pictures or video locally, and clients have to fetch them directly from the source server.
{
# Enable nginx slice module distributed with Tengine
services.nginx.package = pkgs.tengine;
# Enable media proxy
services.akkoma.config.":pleroma".":media_proxy" = {
enabled = true;
proxy_opts.redirect_on_failure = true;
};
# Adjust the persistent cache size as needed:
# Assuming an average object size of 128 KiB, around 1 MiB
# of memory is required for the key zone per GiB of cache.
# Ensure that the cache directory exists and is writable by nginx.
services.nginx.commonHttpConfig = ''
proxy_cache_path /var/cache/nginx/cache/akkoma-media-cache
levels= keys_zone=akkoma_media_cache:16m max_size=16g
inactive=1y use_temp_path=off;
'';
services.akkoma.nginx = {
locations."/proxy" = {
proxyPass = "http://unix:/run/akkoma/socket";
extraConfig = ''
proxy_cache akkoma_media_cache;
# Cache objects in slices of 1 MiB
slice 1m;
proxy_cache_key $host$uri$is_args$args$slice_range;
proxy_set_header Range $slice_range;
# Decouple proxy and upstream responses
proxy_buffering on;
proxy_cache_lock on;
proxy_ignore_client_abort on;
# Default cache times for various responses
proxy_cache_valid 200 1y;
proxy_cache_valid 206 301 304 1h;
# Allow serving of stale items
proxy_cache_use_stale error timeout invalid_header updating;
'';
};
};
}
The following example enables the MediaProxyWarmingPolicy
MRF policy which automatically
fetches all media associated with a post through the media proxy, as soon as the post is
received by the instance.
{
services.akkoma.config.":pleroma".":mrf".policies =
map (pkgs.formats.elixirConf { }).lib.mkRaw [
"Pleroma.Web.ActivityPub.MRF.MediaProxyWarmingPolicy"
];
}
Akkoma can generate previews for media.
{
services.akkoma.config.":pleroma".":media_preview_proxy" = {
enabled = true;
thumbnail_max_width = 1920;
thumbnail_max_height = 1080;
};
}
Akkoma will be deployed with the akkoma-fe
and admin-fe
frontends by default. These can be
modified by setting
services.akkoma.frontends
.
The following example overrides the primary frontend’s default configuration using a custom derivation.
{
services.akkoma.frontends.primary.package = pkgs.runCommand "akkoma-fe" {
config = builtins.toJSON {
expertLevel = 1;
collapseMessageWithSubject = false;
stopGifs = false;
replyVisibility = "following";
webPushHideIfCW = true;
hideScopeNotice = true;
renderMisskeyMarkdown = false;
hideSiteFavicon = true;
postContentType = "text/markdown";
showNavShortcuts = false;
};
nativeBuildInputs = with pkgs; [ jq xorg.lndir ];
passAsFile = [ "config" ];
} ''
mkdir $out
lndir ${pkgs.akkoma-frontends.akkoma-fe} $out
rm $out/static/config.json
jq -s add ${pkgs.akkoma-frontends.akkoma-fe}/static/config.json ${config} \
>$out/static/config.json
'';
}
Akkoma comes with a number of modules to police federation with other ActivityPub instances.
The most valuable for typical users is the
:mrf_simple
module
which allows limiting federation based on instance hostnames.
This configuration snippet provides an example on how these can be used. Choosing an adequate federation policy is not trivial and entails finding a balance between connectivity to the rest of the fediverse and providing a pleasant experience to the users of an instance.
{
services.akkoma.config.":pleroma" = with (pkgs.formats.elixirConf { }).lib; {
":mrf".policies = map mkRaw [
"Pleroma.Web.ActivityPub.MRF.SimplePolicy"
];
":mrf_simple" = {
# Tag all media as sensitive
media_nsfw = mkMap {
"nsfw.weird.kinky" = "Untagged NSFW content";
};
# Reject all activities except deletes
reject = mkMap {
"kiwifarms.cc" = "Persistent harassment of users, no moderation";
};
# Force posts to be visible by followers only
followers_only = mkMap {
"beta.birdsite.live" = "Avoid polluting timelines with Twitter posts";
};
};
};
}
This example strips GPS and location metadata from uploads, deduplicates them and anonymises the the file name.
{
services.akkoma.config.":pleroma"."Pleroma.Upload".filters =
map (pkgs.formats.elixirConf { }).lib.mkRaw [
"Pleroma.Upload.Filter.Exiftool"
"Pleroma.Upload.Filter.Dedupe"
"Pleroma.Upload.Filter.AnonymizeFilename"
];
}
Pleroma instances can be migrated to Akkoma either by copying the database and upload data or by pointing Akkoma to the existing data. The necessary database migrations are run automatically during startup of the service.
The configuration has to be copy‐edited manually.
Depending on the size of the database, the initial migration may take a long time and exceed the
startup timeout of the system manager. To work around this issue one may adjust the startup timeout
systemd.services.akkoma.serviceConfig.TimeoutStartSec
or simply run the migrations
manually:
pleroma_ctl migrate
Copying the Pleroma data instead of re‐using it in place may permit easier reversion to Pleroma, but allows the two data sets to diverge.
First disable Pleroma and then copy its database and upload data:
# Create a copy of the database
nix-shell -p postgresql --run 'createdb -T pleroma akkoma'
# Copy upload data
mkdir /var/lib/akkoma
cp -R --reflink=auto /var/lib/pleroma/uploads /var/lib/akkoma/
After the data has been copied, enable the Akkoma service and verify that the migration has been successful. If no longer required, the original data may then be deleted:
# Delete original database
nix-shell -p postgresql --run 'dropdb pleroma'
# Delete original Pleroma state
rm -r /var/lib/pleroma
To re‐use the Pleroma data in place, disable Pleroma and enable Akkoma, pointing it to the Pleroma database and upload directory.
{
# Adjust these settings according to the database name and upload directory path used by Pleroma
services.akkoma.config.":pleroma"."Pleroma.Repo".database = "pleroma";
services.akkoma.config.":pleroma".":instance".upload_dir = "/var/lib/pleroma/uploads";
}
Please keep in mind that after the Akkoma service has been started, any migrations applied by
Akkoma have to be rolled back before the database can be used again with Pleroma. This can be
achieved through pleroma_ctl ecto.rollback
. Refer to the
Ecto SQL documentation for
details.
The Akkoma systemd service may be confined to a chroot with
{
services.systemd.akkoma.confinement.enable = true;
}
Confinement of services is not generally supported in NixOS and therefore disabled by default. Depending on the Akkoma configuration, the default confinement settings may be insufficient and lead to subtle errors at run time, requiring adjustment:
Use
services.systemd.akkoma.confinement.packages
to make packages available in the chroot.
services.systemd.akkoma.serviceConfig.BindPaths
and
services.systemd.akkoma.serviceConfig.BindReadOnlyPaths
permit access to outside paths
through bind mounts. Refer to
BindPaths=
of systemd.exec(5) for details.
Being an Elixir application, Akkoma can be deployed in a distributed fashion.
This requires setting
services.akkoma.dist.address
and
services.akkoma.dist.cookie
. The
specifics depend strongly on the deployment environment. For more information please check the
relevant Erlang documentation.
The systemd-lock-handler
module provides a service that bridges
D-Bus events from logind
to user-level systemd targets:
lock.target
started by loginctl lock-session
,
unlock.target
started by loginctl unlock-session
and
sleep.target
started by systemctl suspend
.
You can create a user service that starts with any of these targets.
For example, to create a service for swaylock
:
{
services.systemd-lock-handler.enable = true;
systemd.user.services.swaylock = {
description = "Screen locker for Wayland";
documentation = ["man:swaylock(1)"];
# If swaylock exits cleanly, unlock the session:
onSuccess = ["unlock.target"];
# When lock.target is stopped, stops this too:
partOf = ["lock.target"];
# Delay lock.target until this service is ready:
before = ["lock.target"];
wantedBy = ["lock.target"];
serviceConfig = {
# systemd will consider this service started when swaylock forks...
Type = "forking";
# ... and swaylock will fork only after it has locked the screen.
ExecStart = "${lib.getExe pkgs.swaylock} -f";
# If swaylock crashes, always restart it immediately:
Restart = "on-failure";
RestartSec = 0;
};
};
}
See upstream documentation for more information.
Table of Contents
Meilisearch is a lightweight, fast and powerful search engine. Think elastic search with a much smaller footprint.
the minimum to start meilisearch is
{
services.meilisearch.enable = true;
}
this will start the http server included with meilisearch on port 7700.
test with curl -X GET 'http://localhost:7700/health'
you first need to add documents to an index before you can search for documents.
movies
index curl -X POST 'http://127.0.0.1:7700/indexes/movies/documents' --data '[{"id": "123", "title": "Superman"}, {"id": 234, "title": "Batman"}]'
movies
index curl 'http://127.0.0.1:7700/indexes/movies/search' --data '{ "q": "botman" }'
(note the typo is intentional and there to demonstrate the typo tolerant capabilities)
The default nixos package doesn’t come with the dashboard, since the dashboard features makes some assets downloads at compile time.
Anonymized Analytics sent to meilisearch are disabled by default.
Default deployment is development mode. It doesn’t require a secret master key. All routes are not protected and accessible.
the snapshot feature is not yet configurable from the module, it’s just a matter of adding the relevant environment variables.
Table of Contents
Source: modules/services/networking/yggdrasil/default.nix
Upstream documentation: https://yggdrasil-network.github.io/
Yggdrasil is an early-stage implementation of a fully end-to-end encrypted, self-arranging IPv6 network.
An annotated example of a simple configuration:
{
services.yggdrasil = {
enable = true;
persistentKeys = false;
# The NixOS module will generate new keys and a new IPv6 address each time
# it is started if persistentKeys is not enabled.
settings = {
Peers = [
# Yggdrasil will automatically connect and "peer" with other nodes it
# discovers via link-local multicast announcements. Unless this is the
# case (it probably isn't) a node needs peers within the existing
# network that it can tunnel to.
"tcp://1.2.3.4:1024"
"tcp://1.2.3.5:1024"
# Public peers can be found at
# https://github.com/yggdrasil-network/public-peers
];
};
};
}
A node with a fixed address that announces a prefix:
let
address = "210:5217:69c0:9afc:1b95:b9f:8718:c3d2";
prefix = "310:5217:69c0:9afc";
# taken from the output of "yggdrasilctl getself".
in {
services.yggdrasil = {
enable = true;
persistentKeys = true; # Maintain a fixed public key and IPv6 address.
settings = {
Peers = [ "tcp://1.2.3.4:1024" "tcp://1.2.3.5:1024" ];
NodeInfo = {
# This information is visible to the network.
name = config.networking.hostName;
location = "The North Pole";
};
};
};
boot.kernel.sysctl."net.ipv6.conf.all.forwarding" = 1;
# Forward traffic under the prefix.
networking.interfaces.${eth0}.ipv6.addresses = [{
# Set a 300::/8 address on the local physical device.
address = prefix + "::1";
prefixLength = 64;
}];
services.radvd = {
# Announce the 300::/8 prefix to eth0.
enable = true;
config = ''
interface eth0
{
AdvSendAdvert on;
prefix ${prefix}::/64 {
AdvOnLink on;
AdvAutonomous on;
};
route 200::/8 {};
};
'';
};
}
A NixOS container attached to the Yggdrasil network via a node running on the host:
let
yggPrefix64 = "310:5217:69c0:9afc";
# Again, taken from the output of "yggdrasilctl getself".
in
{
boot.kernel.sysctl."net.ipv6.conf.all.forwarding" = 1;
# Enable IPv6 forwarding.
networking = {
bridges.br0.interfaces = [ ];
# A bridge only to containers…
interfaces.br0 = {
# … configured with a prefix address.
ipv6.addresses = [{
address = "${yggPrefix64}::1";
prefixLength = 64;
}];
};
};
containers.foo = {
autoStart = true;
privateNetwork = true;
hostBridge = "br0";
# Attach the container to the bridge only.
config = { config, pkgs, ... }: {
networking.interfaces.eth0.ipv6 = {
addresses = [{
# Configure a prefix address.
address = "${yggPrefix64}::2";
prefixLength = 64;
}];
routes = [{
# Configure the prefix route.
address = "200::";
prefixLength = 7;
via = "${yggPrefix64}::1";
}];
};
services.httpd.enable = true;
networking.firewall.allowedTCPPorts = [ 80 ];
};
};
}
Table of Contents
Prosody is an open-source, modern XMPP server.
A common struggle for most XMPP newcomers is to find the right set of XMPP Extensions (XEPs) to setup. Forget to activate a few of those and your XMPP experience might turn into a nightmare!
The XMPP community tackles this problem by creating a meta-XEP listing a decent set of XEPs you should implement. This meta-XEP is issued every year, the 2020 edition being XEP-0423.
The NixOS Prosody module will implement most of these recommendend XEPs out of
the box. That being said, two components still require some
manual configuration: the
Multi User Chat (MUC)
and the HTTP File Upload ones.
You’ll need to create a DNS subdomain for each of those. The current convention is to name your
MUC endpoint conference.example.org
and your HTTP upload domain upload.example.org
.
A good configuration to start with, including a Multi User Chat (MUC) endpoint as well as a HTTP File Upload endpoint will look like this:
{
services.prosody = {
enable = true;
admins = [ "root@example.org" ];
ssl.cert = "/var/lib/acme/example.org/fullchain.pem";
ssl.key = "/var/lib/acme/example.org/key.pem";
virtualHosts."example.org" = {
enabled = true;
domain = "example.org";
ssl.cert = "/var/lib/acme/example.org/fullchain.pem";
ssl.key = "/var/lib/acme/example.org/key.pem";
};
muc = [ {
domain = "conference.example.org";
} ];
uploadHttp = {
domain = "upload.example.org";
};
};
}
As you can see in the code snippet from the previous section, you’ll need a single TLS certificate covering your main endpoint, the MUC one as well as the HTTP Upload one. We can generate such a certificate by leveraging the ACME extraDomainNames module option.
Provided the setup detailed in the previous section, you’ll need the following acme configuration to generate a TLS certificate for the three endponits:
{
security.acme = {
email = "root@example.org";
acceptTerms = true;
certs = {
"example.org" = {
webroot = "/var/www/example.org";
email = "root@example.org";
extraDomainNames = [ "conference.example.org" "upload.example.org" ];
};
};
};
}
Table of Contents
Pleroma is a lightweight activity pub server.
The pleroma_ctl
CLI utility will prompt you some questions and it will generate an initial config file. This is an example of usage
$ mkdir tmp-pleroma
$ cd tmp-pleroma
$ nix-shell -p pleroma-otp
$ pleroma_ctl instance gen --output config.exs --output-psql setup.psql
The config.exs
file can be further customized following the instructions on the upstream documentation. Many refinements can be applied also after the service is running.
First, the Postgresql service must be enabled in the NixOS configuration
{
services.postgresql = {
enable = true;
package = pkgs.postgresql_13;
};
}
and activated with the usual
$ nixos-rebuild switch
Then you can create and seed the database, using the setup.psql
file that you generated in the previous section, by running
$ sudo -u postgres psql -f setup.psql
In this section we will enable the Pleroma service only locally, so its configurations can be improved incrementally.
This is an example of configuration, where services.pleroma.configs
option contains the content of the file config.exs
, generated in the first section, but with the secrets (database password, endpoint secret key, salts, etc.) removed. Removing secrets is important, because otherwise they will be stored publicly in the Nix store.
{
services.pleroma = {
enable = true;
secretConfigFile = "/var/lib/pleroma/secrets.exs";
configs = [
''
import Config
config :pleroma, Pleroma.Web.Endpoint,
url: [host: "pleroma.example.net", scheme: "https", port: 443],
http: [ip: {127, 0, 0, 1}, port: 4000]
config :pleroma, :instance,
name: "Test",
email: "admin@example.net",
notify_email: "admin@example.net",
limit: 5000,
registrations_open: true
config :pleroma, :media_proxy,
enabled: false,
redirect_on_failure: true
config :pleroma, Pleroma.Repo,
adapter: Ecto.Adapters.Postgres,
username: "pleroma",
database: "pleroma",
hostname: "localhost"
# Configure web push notifications
config :web_push_encryption, :vapid_details,
subject: "mailto:admin@example.net"
# ... TO CONTINUE ...
''
];
};
}
Secrets must be moved into a file pointed by services.pleroma.secretConfigFile
, in our case /var/lib/pleroma/secrets.exs
. This file can be created copying the previously generated config.exs
file and then removing all the settings, except the secrets. This is an example
# Pleroma instance passwords
import Config
config :pleroma, Pleroma.Web.Endpoint,
secret_key_base: "<the secret generated by pleroma_ctl>",
signing_salt: "<the secret generated by pleroma_ctl>"
config :pleroma, Pleroma.Repo,
password: "<the secret generated by pleroma_ctl>"
# Configure web push notifications
config :web_push_encryption, :vapid_details,
public_key: "<the secret generated by pleroma_ctl>",
private_key: "<the secret generated by pleroma_ctl>"
# ... TO CONTINUE ...
Note that the lines of the same configuration group are comma separated (i.e. all the lines end with a comma, except the last one), so when the lines with passwords are added or removed, commas must be adjusted accordingly.
The service can be enabled with the usual
$ nixos-rebuild switch
The service is accessible only from the local 127.0.0.1:4000
port. It can be tested using a port forwarding like this
$ ssh -L 4000:localhost:4000 myuser@example.net
and then accessing http://localhost:4000 from a web browser.
After Pleroma service is running, all Pleroma administration utilities can be used. In particular an admin user can be created with
$ pleroma_ctl user new <nickname> <email> --admin --moderator --password <password>
In this configuration, Pleroma is listening only on the local port 4000. Nginx can be configured as a Reverse Proxy, for forwarding requests from public ports to the Pleroma service. This is an example of configuration, using Let’s Encrypt for the TLS certificates
{
security.acme = {
email = "root@example.net";
acceptTerms = true;
};
services.nginx = {
enable = true;
addSSL = true;
recommendedTlsSettings = true;
recommendedOptimisation = true;
recommendedGzipSettings = true;
recommendedProxySettings = false;
# NOTE: if enabled, the NixOS proxy optimizations will override the Pleroma
# specific settings, and they will enter in conflict.
virtualHosts = {
"pleroma.example.net" = {
http2 = true;
enableACME = true;
forceSSL = true;
locations."/" = {
proxyPass = "http://127.0.0.1:4000";
extraConfig = ''
etag on;
gzip on;
add_header 'Access-Control-Allow-Origin' '*' always;
add_header 'Access-Control-Allow-Methods' 'POST, PUT, DELETE, GET, PATCH, OPTIONS' always;
add_header 'Access-Control-Allow-Headers' 'Authorization, Content-Type, Idempotency-Key' always;
add_header 'Access-Control-Expose-Headers' 'Link, X-RateLimit-Reset, X-RateLimit-Limit, X-RateLimit-Remaining, X-Request-Id' always;
if ($request_method = OPTIONS) {
return 204;
}
add_header X-XSS-Protection "1; mode=block";
add_header X-Permitted-Cross-Domain-Policies none;
add_header X-Frame-Options DENY;
add_header X-Content-Type-Options nosniff;
add_header Referrer-Policy same-origin;
add_header X-Download-Options noopen;
proxy_http_version 1.1;
proxy_set_header Upgrade $http_upgrade;
proxy_set_header Connection "upgrade";
proxy_set_header Host $host;
client_max_body_size 16m;
# NOTE: increase if users need to upload very big files
'';
};
};
};
};
}
Table of Contents
NetBird is a VPN built on top of WireGuard® making it easy to create secure private networks for your organization or home.
To fully setup Netbird as a self-hosted server, we need both a Coturn server and an identity provider, the list of supported SSOs and their setup are available on Netbird’s documentation.
There are quite a few settings that need to be passed to Netbird for it to function, and a minimal config looks like :
services.netbird.server = {
enable = true;
domain = "netbird.example.selfhosted";
enableNginx = true;
coturn = {
enable = true;
passwordFile = "/path/to/a/secret/password";
};
management = {
oidcConfigEndpoint = "https://sso.example.selfhosted/oauth2/openid/netbird/.well-known/openid-configuration";
settings = {
TURNConfig = {
Turns = [
{
Proto = "udp";
URI = "turn:netbird.example.selfhosted:3478";
Username = "netbird";
Password._secret = "/path/to/a/secret/password";
}
];
};
};
};
};
Table of Contents
The absolute minimal configuration for the netbird daemon looks like this:
{
services.netbird.enable = true;
}
This will set up a netbird service listening on the port 51820
associated to the
wt0
interface.
It is strictly equivalent to setting:
{
services.netbird.tunnels.wt0.stateDir = "netbird";
}
The enable
option is mainly kept for backward compatibility, as defining netbird
tunnels through the tunnels
option is more expressive.
Using the services.netbird.tunnels
option, it is also possible to define more than
one netbird service running at the same time.
The following configuration will start a netbird daemon using the interface wt1
and
the port 51830. Its configuration file will then be located at /var/lib/netbird-wt1/config.json
.
{
services.netbird.tunnels = {
wt1 = {
port = 51830;
};
};
}
To interact with it, you will need to specify the correct daemon address:
netbird --daemon-addr unix:///var/run/netbird-wt1/sock ...
The address will by default be unix:///var/run/netbird-<name>
.
It is also possible to overwrite default options passed to the service, for example:
{
services.netbird.tunnels.wt1.environment = {
NB_DAEMON_ADDR = "unix:///var/run/toto.sock";
};
}
This will set the socket to interact with the netbird service to /var/run/toto.sock
.
Table of Contents
Mosquitto is a MQTT broker often used for IoT or home automation data transport.
A minimal configuration for Mosquitto is
{
services.mosquitto = {
enable = true;
listeners = [ {
acl = [ "pattern readwrite #" ];
omitPasswordAuth = true;
settings.allow_anonymous = true;
} ];
};
}
This will start a broker on port 1883, listening on all interfaces of the machine, allowing read/write access to all topics to any user without password requirements.
User authentication can be configured with the users
key of listeners. A config that gives
full read access to a user monitor
and restricted write access to a user service
could look
like
{
services.mosquitto = {
enable = true;
listeners = [ {
users = {
monitor = {
acl = [ "read #" ];
password = "monitor";
};
service = {
acl = [ "write service/#" ];
password = "service";
};
};
} ];
};
}
TLS authentication is configured by setting TLS-related options of the listener:
{
services.mosquitto = {
enable = true;
listeners = [ {
port = 8883; # port change is not required, but helpful to avoid mistakes
# ...
settings = {
cafile = "/path/to/mqtt.ca.pem";
certfile = "/path/to/mqtt.pem";
keyfile = "/path/to/mqtt.key";
};
} ];
};
}
The Mosquitto configuration has four distinct types of settings: the global settings of the daemon, listeners, plugins, and bridges. Bridges and listeners are part of the global configuration, plugins are part of listeners. Users of the broker are configured as parts of listeners rather than globally, allowing configurations in which a given user is only allowed to log in to the broker using specific listeners (eg to configure an admin user with full access to all topics, but restricted to localhost).
Almost all options of Mosquitto are available for configuration at their appropriate levels, some
as NixOS options written in camel case, the remainders under settings
with their exact names in
the Mosquitto config file. The exceptions are acl_file
(which is always set according to the
acl
attributes of a listener and its users) and per_listener_settings
(which is always set to
true
).
Mosquitto can be run in two modes, with a password file or without. Each listener has its own
password file, and different listeners may use different password files. Password file generation
can be disabled by setting omitPasswordAuth = true
for a listener; in this case it is necessary
to either set settings.allow_anonymous = true
to allow all logins, or to configure other
authentication methods like TLS client certificates with settings.use_identity_as_username = true
.
The default is to generate a password file for each listener from the users configured to that listener. Users with no configured password will not be added to the password file and thus will not be able to use the broker.
Every listener has a Mosquitto acl_file
attached to it. This ACL is configured via two
attributes of the config:
the acl
attribute of the listener configures pattern ACL entries and topic ACL entries
for anonymous users. Each entry must be prefixed with pattern
or topic
to distinguish
between these two cases.
the acl
attribute of every user configures in the listener configured the ACL for that
given user. Only topic ACLs are supported by Mosquitto in this setting, so no prefix is
required or allowed.
The default ACL for a listener is empty, disallowing all accesses from all clients. To configure
a completely open ACL, set acl = [ "pattern readwrite #" ]
in the listener.
Table of Contents
The Jottacloud Command-line Tool is a headless Jottacloud client.
{
services.jotta-cli.enable = true;
}
This adds jotta-cli
to environment.systemPackages
and starts a user service that runs jottad
with the default options.
services.jotta-cli = {
enable = true;
options = [ "slow" ];
package = pkgs.jotta-cli;
};
This uses jotta-cli
and jottad
from the pkgs.jotta-cli
package and starts jottad
in low memory mode.
jottad
is also added to environment.systemPackages
, so jottad --help
can be used to explore options.
Table of Contents
GNS3, a network software emulator.
A minimal configuration looks like this:
{
services.gns3-server = {
enable = true;
auth = {
enable = true;
user = "gns3";
passwordFile = "/var/lib/secrets/gns3_password";
};
ssl = {
enable = true;
certFile = "/var/lib/gns3/ssl/cert.pem";
keyFile = "/var/lib/gns3/ssl/key.pem";
};
dynamips.enable = true;
ubridge.enable = true;
vpcs.enable = true;
};
}
Table of Contents
A storage server for Firefox Sync that you can easily host yourself.
The absolute minimal configuration for the sync server looks like this:
{
services.mysql.package = pkgs.mariadb;
services.firefox-syncserver = {
enable = true;
secrets = builtins.toFile "sync-secrets" ''
SYNC_MASTER_SECRET=this-secret-is-actually-leaked-to-/nix/store
'';
singleNode = {
enable = true;
hostname = "localhost";
url = "http://localhost:5000";
};
};
}
This will start a sync server that is only accessible locally. Once the services is
running you can navigate to about:config
in your Firefox profile and set
identity.sync.tokenserver.uri
to http://localhost:5000/1.0/sync/1.5
. Your browser
will now use your local sync server for data storage.
This configuration should never be used in production. It is not encrypted and stores its secrets in a world-readable location.
The firefox-syncserver
service provides a number of options to make setting up
small deployment easier. These are grouped under the singleNode
element of the
option tree and allow simple configuration of the most important parameters.
Single node setup is split into two kinds of options: those that affect the sync
server itself, and those that affect its surroundings. Options that affect the
sync server are capacity
, which configures how many accounts may be active on
this instance, and url
, which holds the URL under which the sync server can be
accessed. The url
can be configured automatically when using nginx.
Options that affect the surroundings of the sync server are enableNginx
,
enableTLS
and hostname
. If enableNginx
is set the sync server module will
automatically add an nginx virtual host to the system using hostname
as the
domain and set url
accordingly. If enableTLS
is set the module will also
enable ACME certificates on the new virtual host and force all connections to
be made via TLS.
For actual deployment it is also recommended to store the secrets
file in a
secure location.
Table of Contents
Dnsmasq is an integrated DNS, DHCP and TFTP server for small networks.
On a home network, you can use Dnsmasq as a DHCP and DNS server. New devices on your network will be configured by Dnsmasq, and instructed to use it as the DNS server by default. This allows you to rely on your own server to perform DNS queries and caching, with DNSSEC enabled.
The following example assumes that
you have disabled your router’s integrated DHCP server, if it has one
your router’s address is set in networking.defaultGateway.address
your system’s Ethernet interface is eth0
you have configured the address(es) to forward DNS queries in networking.nameservers
{
services.dnsmasq = {
enable = true;
settings = {
interface = "eth0";
bind-interfaces = true; # Only bind to the specified interface
dhcp-authoritative = true; # Should be set when dnsmasq is definitely the only DHCP server on a network
server = config.networking.nameservers; # Upstream dns servers to which requests should be forwarded
dhcp-host = [
# Give the current system a fixed address of 192.168.0.254
"dc:a6:32:0b:ea:b9,192.168.0.254,${config.networking.hostName},infinite"
];
dhcp-option = [
# Address of the gateway, i.e. your router
"option:router,${config.networking.defaultGateway.address}"
];
dhcp-range = [
# Range of IPv4 addresses to give out
# <range start>,<range end>,<lease time>
"192.168.0.10,192.168.0.253,24h"
# Enable stateless IPv6 allocation
"::f,::ff,constructor:eth0,ra-stateless"
];
dhcp-rapid-commit = true; # Faster DHCP negotiation for IPv6
local-service = true; # Accept DNS queries only from hosts whose address is on a local subnet
log-queries = true; # Log results of all DNS queries
bogus-priv = true; # Don't forward requests for the local address ranges (192.168.x.x etc) to upstream nameservers
domain-needed = true; # Don't forward requests without dots or domain parts to upstream nameservers
dnssec = true; # Enable DNSSEC
# DNSSEC trust anchor. Source: https://data.iana.org/root-anchors/root-anchors.xml
trust-anchor = ".,20326,8,2,E06D44B80B8F1D39A95C0B0D7C65D08458E880409BBC683457104237C7F8EC8D";
};
};
}
Upstream website: https://dnsmasq.org
Table of Contents
Litestream is a standalone streaming replication tool for SQLite.
Litestream service is managed by a dedicated user named litestream
which needs permission to the database file. Here’s an example config which gives
required permissions to access grafana database:
{ pkgs, ... }:
{
users.users.litestream.extraGroups = [ "grafana" ];
systemd.services.grafana.serviceConfig.ExecStartPost = "+" + pkgs.writeShellScript "grant-grafana-permissions" ''
timeout=10
while [ ! -f /var/lib/grafana/data/grafana.db ];
do
if [ "$timeout" == 0 ]; then
echo "ERROR: Timeout while waiting for /var/lib/grafana/data/grafana.db."
exit 1
fi
sleep 1
((timeout--))
done
find /var/lib/grafana -type d -exec chmod -v 775 {} \;
find /var/lib/grafana -type f -exec chmod -v 660 {} \;
'';
services.litestream = {
enable = true;
environmentFile = "/run/secrets/litestream";
settings = {
dbs = [
{
path = "/var/lib/grafana/data/grafana.db";
replicas = [{
url = "s3://mybkt.litestream.io/grafana";
}];
}
];
};
};
}
Table of Contents
Prometheus exporters provide metrics for the prometheus monitoring system.
One of the most common exporters is the node exporter, it provides hardware and OS metrics from the host it’s running on. The exporter could be configured as follows:
{
services.prometheus.exporters.node = {
enable = true;
port = 9100;
enabledCollectors = [
"logind"
"systemd"
];
disabledCollectors = [
"textfile"
];
openFirewall = true;
firewallFilter = "-i br0 -p tcp -m tcp --dport 9100";
};
}
It should now serve all metrics from the collectors that are explicitly
enabled and the ones that are
enabled by default,
via http under /metrics
. In this
example the firewall should just allow incoming connections to the
exporter’s port on the bridge interface br0
(this would
have to be configured separately of course). For more information about
configuration see man configuration.nix
or search through
the available options.
Prometheus can now be configured to consume the metrics produced by the exporter:
{
services.prometheus = {
# ...
scrapeConfigs = [
{
job_name = "node";
static_configs = [{
targets = [ "localhost:${toString config.services.prometheus.exporters.node.port}" ];
}];
}
];
# ...
};
}
To add a new exporter, it has to be packaged first (see
nixpkgs/pkgs/servers/monitoring/prometheus/
for
examples), then a module can be added. The postfix exporter is used in this
example:
Some default options for all exporters are provided by
nixpkgs/nixos/modules/services/monitoring/prometheus/exporters.nix
:
enable
port
listenAddress
extraFlags
openFirewall
firewallFilter
firewallRules
user
group
As there is already a package available, the module can now be added. This
is accomplished by adding a new file to the
nixos/modules/services/monitoring/prometheus/exporters/
directory, which will be called postfix.nix and contains all exporter
specific options and configuration:
# nixpkgs/nixos/modules/services/prometheus/exporters/postfix.nix
{ config, lib, pkgs, options }:
with lib;
let
# for convenience we define cfg here
cfg = config.services.prometheus.exporters.postfix;
in
{
port = 9154; # The postfix exporter listens on this port by default
# `extraOpts` is an attribute set which contains additional options
# (and optional overrides for default options).
# Note that this attribute is optional.
extraOpts = {
telemetryPath = mkOption {
type = types.str;
default = "/metrics";
description = ''
Path under which to expose metrics.
'';
};
logfilePath = mkOption {
type = types.path;
default = /var/log/postfix_exporter_input.log;
example = /var/log/mail.log;
description = ''
Path where Postfix writes log entries.
This file will be truncated by this exporter!
'';
};
showqPath = mkOption {
type = types.path;
default = /var/spool/postfix/public/showq;
example = /var/lib/postfix/queue/public/showq;
description = ''
Path at which Postfix places its showq socket.
'';
};
};
# `serviceOpts` is an attribute set which contains configuration
# for the exporter's systemd service. One of
# `serviceOpts.script` and `serviceOpts.serviceConfig.ExecStart`
# has to be specified here. This will be merged with the default
# service configuration.
# Note that by default 'DynamicUser' is 'true'.
serviceOpts = {
serviceConfig = {
DynamicUser = false;
ExecStart = ''
${pkgs.prometheus-postfix-exporter}/bin/postfix_exporter \
--web.listen-address ${cfg.listenAddress}:${toString cfg.port} \
--web.telemetry-path ${cfg.telemetryPath} \
${concatStringsSep " \\\n " cfg.extraFlags}
'';
};
};
}
This should already be enough for the postfix exporter. Additionally one
could now add assertions and conditional default values. This can be done
in the ‘meta-module’ that combines all exporter definitions and generates
the submodules:
nixpkgs/nixos/modules/services/prometheus/exporters.nix
Should an exporter option change at some point, it is possible to add
information about the change to the exporter definition similar to
nixpkgs/nixos/modules/rename.nix
:
{ config, lib, pkgs, options }:
with lib;
let
cfg = config.services.prometheus.exporters.nginx;
in
{
port = 9113;
extraOpts = {
# additional module options
# ...
};
serviceOpts = {
# service configuration
# ...
};
imports = [
# 'services.prometheus.exporters.nginx.telemetryEndpoint' -> 'services.prometheus.exporters.nginx.telemetryPath'
(mkRenamedOptionModule [ "telemetryEndpoint" ] [ "telemetryPath" ])
# removed option 'services.prometheus.exporters.nginx.insecure'
(mkRemovedOptionModule [ "insecure" ] ''
This option was replaced by 'prometheus.exporters.nginx.sslVerify' which defaults to true.
'')
({ options.warnings = options.warnings; })
];
}
Table of Contents
parsedmarc is a service which parses incoming DMARC reports and stores or sends them to a downstream service for further analysis. In combination with Elasticsearch, Grafana and the included Grafana dashboard, it provides a handy overview of DMARC reports over time.
A very minimal setup which reads incoming reports from an external email address and saves them to a local Elasticsearch instance looks like this:
{
services.parsedmarc = {
enable = true;
settings.imap = {
host = "imap.example.com";
user = "alice@example.com";
password = "/path/to/imap_password_file";
};
provision.geoIp = false; # Not recommended!
};
}
Note that GeoIP provisioning is disabled in the example for simplicity, but should be turned on for fully functional reports.
Instead of watching an external inbox, a local inbox can be
automatically provisioned. The recipient’s name is by default set to
dmarc
, but can be configured in
services.parsedmarc.provision.localMail.recipientName. You
need to add an MX record pointing to the host. More concretely: for
the example to work, an MX record needs to be set up for
monitoring.example.com
and the complete email address that should be
configured in the domain’s dmarc policy is
dmarc@monitoring.example.com
.
{
services.parsedmarc = {
enable = true;
provision = {
localMail = {
enable = true;
hostname = monitoring.example.com;
};
geoIp = false; # Not recommended!
};
};
}
The reports can be visualized and summarized with parsedmarc’s official Grafana dashboard. For all views to work, and for the data to be complete, GeoIP databases are also required. The following example shows a basic deployment where the provisioned Elasticsearch instance is automatically added as a Grafana datasource, and the dashboard is added to Grafana as well.
{
services.parsedmarc = {
enable = true;
provision = {
localMail = {
enable = true;
hostname = url;
};
grafana = {
datasource = true;
dashboard = true;
};
};
};
# Not required, but recommended for full functionality
services.geoipupdate = {
settings = {
AccountID = 000000;
LicenseKey = "/path/to/license_key_file";
};
};
services.grafana = {
enable = true;
addr = "0.0.0.0";
domain = url;
rootUrl = "https://" + url;
protocol = "socket";
security = {
adminUser = "admin";
adminPasswordFile = "/path/to/admin_password_file";
secretKeyFile = "/path/to/secret_key_file";
};
};
services.nginx = {
enable = true;
recommendedTlsSettings = true;
recommendedOptimisation = true;
recommendedGzipSettings = true;
recommendedProxySettings = true;
upstreams.grafana.servers."unix:/${config.services.grafana.socket}" = {};
virtualHosts.${url} = {
root = config.services.grafana.staticRootPath;
enableACME = true;
forceSSL = true;
locations."/".tryFiles = "$uri @grafana";
locations."@grafana".proxyPass = "http://grafana";
};
};
users.users.nginx.extraGroups = [ "grafana" ];
}
Table of Contents
OCS Inventory NG or Open Computers and Software inventory is an application designed to help IT administrator to keep track of the hardware and software configurations of computers that are installed on their network.
OCS Inventory collects information about the hardware and software of networked machines through the OCS Inventory Agent program.
This NixOS module enables you to install and configure this agent so that it sends information from your computer to the OCS Inventory server.
For more technical information about OCS Inventory Agent, refer to the Wiki documentation.
A minimal configuration looks like this:
{
services.ocsinventory-agent = {
enable = true;
settings = {
server = "https://ocsinventory.localhost:8080/ocsinventory";
tag = "01234567890123";
};
};
}
This configuration will periodically run the ocsinventory-agent SystemD service.
The OCS Inventory Agent will inventory the computer and then sends the results to the specified OCS Inventory Server.
Table of Contents
goss is a YAML based serverspec alternative tool for validating a server’s configuration.
A minimal configuration looks like this:
{
services.goss = {
enable = true;
environment = {
GOSS_FMT = "json";
GOSS_LOGLEVEL = "TRACE";
};
settings = {
addr."tcp://localhost:8080" = {
reachable = true;
local-address = "127.0.0.1";
};
command."check-goss-version" = {
exec = "${lib.getExe pkgs.goss} --version";
exit-status = 0;
};
dns.localhost.resolvable = true;
file."/nix" = {
filetype = "directory";
exists = true;
};
group.root.exists = true;
kernel-param."kernel.ostype".value = "Linux";
service.goss = {
enabled = true;
running = true;
};
user.root.exists = true;
};
};
}
Table of Contents
Cert Spotter is a tool for monitoring Certificate Transparency logs.
A basic config that notifies you of all certificate changes for your domain would look as follows:
{
services.certspotter = {
enable = true;
# replace example.org with your domain name
watchlist = [ ".example.org" ];
emailRecipients = [ "webmaster@example.org" ];
};
# Configure an SMTP client
programs.msmtp.enable = true;
# Or you can use any other module that provides sendmail, like
# services.nullmailer, services.opensmtpd, services.postfix
}
In this case, the leading dot in ".example.org"
means that Cert
Spotter should monitor not only example.org
, but also all of its
subdomains.
By default, NixOS configures Cert Spotter to skip all certificates
issued before its first launch, because checking the entire
Certificate Transparency logs requires downloading tens of terabytes of
data. If you want to check the entire logs for previously issued
certificates, you have to set services.certspotter.startAtEnd
to
false
and remove all previously saved log state in
/var/lib/certspotter/logs
. The downloaded logs aren’t saved, so if you
add a new domain to the watchlist and want Cert Spotter to go through
the logs again, you will have to remove /var/lib/certspotter/logs
again.
After catching up with the logs, Cert Spotter will start monitoring live logs. As of October 2023, it uses around 20 Mbps of traffic on average.
Cert Spotter supports running custom hooks instead of (or in addition to) sending emails. Hooks are shell scripts that will be passed certain environment variables.
To see hook documentation, see Cert Spotter’s man pages:
nix-shell -p certspotter --run 'man 8 certspotter-script'
For example, you can remove emailRecipients
and send email
notifications manually using the following hook:
{
services.certspotter.hooks = [
(pkgs.writeShellScript "certspotter-hook" ''
function print_email() {
echo "Subject: [certspotter] $SUMMARY"
echo "Mime-Version: 1.0"
echo "Content-Type: text/plain; charset=US-ASCII"
echo
cat "$TEXT_FILENAME"
}
print_email | ${config.services.certspotter.sendmailPath} -i webmaster@example.org
'')
];
}
Table of Contents
WeeChat is a fast and extensible IRC client.
By default, the module creates a
systemd
unit which runs the chat client in a detached
screen
session.
This can be done by enabling the weechat
service:
{ ... }:
{
services.weechat.enable = true;
}
The service is managed by a dedicated user named weechat
in the state directory /var/lib/weechat
.
WeeChat runs in a screen session owned by a dedicated user. To explicitly
allow your another user to attach to this session, the
screenrc
needs to be tweaked by adding
multiuser
support:
{
programs.screen.screenrc = ''
multiuser on
acladd normal_user
'';
}
Now, the session can be re-attached like this:
screen -x weechat/weechat-screen
The session name can be changed using services.weechat.sessionName.
Table of Contents
Taskserver is the server component of Taskwarrior, a free and open source todo list application.
Upstream documentation: https://taskwarrior.org/docs/#taskd
Taskserver does all of its authentication via TLS using client certificates, so you either need to roll your own CA or purchase a certificate from a known CA, which allows creation of client certificates. These certificates are usually advertised as “server certificates”.
So in order to make it easier to handle your own CA, there is a helper tool called nixos-taskserver which manages the custom CA along with Taskserver organisations, users and groups.
While the client certificates in Taskserver only authenticate whether a user is allowed to connect, every user has its own UUID which identifies it as an entity.
With nixos-taskserver the client certificate is created along with the UUID of the user, so it handles all of the credentials needed in order to setup the Taskwarrior client to work with a Taskserver.
Because Taskserver by default only provides scripts to setup users
imperatively, the nixos-taskserver tool is used for
addition and deletion of organisations along with users and groups defined
by services.taskserver.organisations
and as well for
imperative set up.
The tool is designed to not interfere if the command is used to manually set up some organisations, users or groups.
For example if you add a new organisation using nixos-taskserver org add foo, the organisation is not modified and deleted no
matter what you define in
services.taskserver.organisations
, even if you’re adding
the same organisation in that option.
The tool is modelled to imitate the official taskd
command, documentation for each subcommand can be shown by using the
--help
switch.
Everything is done according to what you specify in the module options, however in order to set up a Taskwarrior client for synchronisation with a Taskserver instance, you have to transfer the keys and certificates to the client machine.
This is done using nixos-taskserver user export $orgname $username which is printing a shell script fragment to stdout which can either be used verbatim or adjusted to import the user on the client machine.
For example, let’s say you have the following configuration:
{
services.taskserver.enable = true;
services.taskserver.fqdn = "server";
services.taskserver.listenHost = "::";
services.taskserver.organisations.my-company.users = [ "alice" ];
}
This creates an organisation called my-company
with the
user alice
.
Now in order to import the alice
user to another machine
alicebox
, all we need to do is something like this:
$ ssh server nixos-taskserver user export my-company alice | sh
Of course, if no SSH daemon is available on the server you can also copy & paste it directly into a shell.
After this step the user should be set up and you can start synchronising
your tasks for the first time with task sync init on
alicebox
.
Subsequent synchronisation requests merely require the command task sync after that stage.
If you set any options within service.taskserver.pki.manual.*, nixos-taskserver won’t issue certificates, but you can still use it for adding or removing user accounts.
Table of Contents
Sourcehut is an open-source, self-hostable software development platform. The server setup can be automated using services.sourcehut.
Sourcehut is a Python and Go based set of applications.
This NixOS module also provides basic configuration integrating Sourcehut into locally running
services.nginx
, services.redis.servers.sourcehut
, services.postfix
and services.postgresql
services.
A very basic configuration may look like this:
{ pkgs, ... }:
let
fqdn =
let
join = hostName: domain: hostName + optionalString (domain != null) ".${domain}";
in join config.networking.hostName config.networking.domain;
in {
networking = {
hostName = "srht";
domain = "tld";
firewall.allowedTCPPorts = [ 22 80 443 ];
};
services.sourcehut = {
enable = true;
git.enable = true;
man.enable = true;
meta.enable = true;
nginx.enable = true;
postfix.enable = true;
postgresql.enable = true;
redis.enable = true;
settings = {
"sr.ht" = {
environment = "production";
global-domain = fqdn;
origin = "https://${fqdn}";
# Produce keys with srht-keygen from sourcehut.coresrht.
network-key = "/run/keys/path/to/network-key";
service-key = "/run/keys/path/to/service-key";
};
webhooks.private-key= "/run/keys/path/to/webhook-key";
};
};
security.acme.certs."${fqdn}".extraDomainNames = [
"meta.${fqdn}"
"man.${fqdn}"
"git.${fqdn}"
];
services.nginx = {
enable = true;
# only recommendedProxySettings are strictly required, but the rest make sense as well.
recommendedTlsSettings = true;
recommendedOptimisation = true;
recommendedGzipSettings = true;
recommendedProxySettings = true;
# Settings to setup what certificates are used for which endpoint.
virtualHosts = {
"${fqdn}".enableACME = true;
"meta.${fqdn}".useACMEHost = fqdn;
"man.${fqdn}".useACMEHost = fqdn;
"git.${fqdn}".useACMEHost = fqdn;
};
};
}
The hostName
option is used internally to configure the nginx
reverse-proxy. The settings
attribute set is
used by the configuration generator and the result is placed in /etc/sr.ht/config.ini
.
All configuration parameters are also stored in
/etc/sr.ht/config.ini
which is generated by
the module and linked from the store to ensure that all values from config.ini
can be modified by the module.
httpd
) By default, nginx
is used as reverse-proxy for sourcehut
.
However, it’s possible to use e.g. httpd
by explicitly disabling
nginx
using services.nginx.enable
and fixing the
settings
.
Table of Contents
GitLab is a feature-rich git hosting service.
The gitlab
service exposes only an Unix socket at
/run/gitlab/gitlab-workhorse.socket
. You need to
configure a webserver to proxy HTTP requests to the socket.
For instance, the following configuration could be used to use nginx as frontend proxy:
{
services.nginx = {
enable = true;
recommendedGzipSettings = true;
recommendedOptimisation = true;
recommendedProxySettings = true;
recommendedTlsSettings = true;
virtualHosts."git.example.com" = {
enableACME = true;
forceSSL = true;
locations."/".proxyPass = "http://unix:/run/gitlab/gitlab-workhorse.socket";
};
};
}
GitLab depends on both PostgreSQL and Redis and will automatically enable both services. In the case of PostgreSQL, a database and a role will be created.
The default state dir is /var/gitlab/state
. This is where
all data like the repositories and uploads will be stored.
A basic configuration with some custom settings could look like this:
{
services.gitlab = {
enable = true;
databasePasswordFile = "/var/keys/gitlab/db_password";
initialRootPasswordFile = "/var/keys/gitlab/root_password";
https = true;
host = "git.example.com";
port = 443;
user = "git";
group = "git";
smtp = {
enable = true;
address = "localhost";
port = 25;
};
secrets = {
dbFile = "/var/keys/gitlab/db";
secretFile = "/var/keys/gitlab/secret";
otpFile = "/var/keys/gitlab/otp";
jwsFile = "/var/keys/gitlab/jws";
};
extraConfig = {
gitlab = {
email_from = "gitlab-no-reply@example.com";
email_display_name = "Example GitLab";
email_reply_to = "gitlab-no-reply@example.com";
default_projects_features = { builds = false; };
};
};
};
}
If you’re setting up a new GitLab instance, generate new
secrets. You for instance use
tr -dc A-Za-z0-9 < /dev/urandom | head -c 128 > /var/keys/gitlab/db
to
generate a new db secret. Make sure the files can be read by, and
only by, the user specified by
services.gitlab.user. GitLab
encrypts sensitive data stored in the database. If you’re restoring
an existing GitLab instance, you must specify the secrets secret
from config/secrets.yml
located in your GitLab
state folder.
When incoming_mail.enabled
is set to true
in extraConfig an additional
service called gitlab-mailroom
is enabled for fetching incoming mail.
Refer to Appendix A for all available configuration options for the services.gitlab module.
Backups can be configured with the options in services.gitlab.backup. Use the services.gitlab.backup.startAt option to configure regular backups.
To run a manual backup, start the gitlab-backup
service:
$ systemctl start gitlab-backup.service
You can run GitLab’s rake tasks with gitlab-rake
which will be available on the system when GitLab is enabled. You
will have to run the command as the user that you configured to run
GitLab with.
A list of all available rake tasks can be obtained by running:
$ sudo -u git -H gitlab-rake -T
Table of Contents
Forgejo is a soft-fork of gitea, with strong community focus, as well as on self-hosting and federation. Codeberg is deployed from it.
See upstream docs.
The method of choice for running forgejo is using services.forgejo
.
Running forgejo using services.gitea.package = pkgs.forgejo
is no longer
recommended.
If you experience issues with your instance using services.gitea
,
DO NOT report them to the services.gitea
module maintainers.
DO report them to the services.forgejo
module maintainers instead.
Migrating is, while not strictly necessary at this point, highly recommended. Both modules and projects are likely to diverge further with each release. Which might lead to an even more involved migration.
This will migrate the state directory (data), rename and chown the database and delete the gitea user.
This will also change the git remote ssh-url user from gitea@
to forgejo@
,
when using the host’s openssh server (default) instead of the integrated one.
Instructions for PostgreSQL (default). Adapt accordingly for other databases:
systemctl stop gitea
mv /var/lib/gitea /var/lib/forgejo
runuser -u postgres -- psql -c '
ALTER USER gitea RENAME TO forgejo;
ALTER DATABASE gitea RENAME TO forgejo;
'
nixos-rebuild switch
systemctl stop forgejo
chown -R forgejo:forgejo /var/lib/forgejo
systemctl restart forgejo
Alternatively, instead of renaming the database, copying the state folder and
changing the user, the forgejo module can be set up to re-use the old storage
locations and database, instead of having to copy or rename them.
Make sure to disable services.gitea
, when doing this.
{
services.gitea.enable = false;
services.forgejo = {
enable = true;
user = "gitea";
group = "gitea";
stateDir = "/var/lib/gitea";
database.name = "gitea";
database.user = "gitea";
};
users.users.gitea = {
home = "/var/lib/gitea";
useDefaultShell = true;
group = "gitea";
isSystemUser = true;
};
users.groups.gitea = {};
}
Table of Contents
Apache Kafka is an open-source distributed event streaming platform
The Apache Kafka service is configured almost exclusively through its settings option, with each attribute corresponding to the upstream configuration manual broker settings.
Unlike in Zookeeper mode, Kafka in KRaft mode requires each log dir to be “formatted” (which means a cluster-specific a metadata file must exist in each log dir)
The upstream intention is for users to execute the storage tool to achieve this, but this module contains a few extra options to automate this:
Migrating a cluster to the new settings
-based changes requires adapting removed options to the corresponding upstream settings.
This means that the upstream Broker Configs documentation should be followed closely.
Note that dotted options in the upstream docs do not correspond to nested Nix attrsets, but instead as quoted top level settings
attributes, as in services.apache-kafka.settings."broker.id"
, NOT services.apache-kafka.settings.broker.id
.
Care should be taken, especially when migrating clusters from the old module, to ensure that the same intended configuration is reproduced faithfully via settings
.
To assist in the comparison, the final config can be inspected by building the config file itself, ie. with: nix-build <nixpkgs/nixos> -A config.services.apache-kafka.configFiles.serverProperties
.
Notable changes to be aware of include:
Removal of services.apache-kafka.extraProperties
and services.apache-kafka.serverProperties
Translate using arbitrary properties using services.apache-kafka.settings
The intention is for all broker properties to be fully representable via services.apache-kafka.settings
.
If this is not the case, please do consider raising an issue.
Until it can be remedied, you can bail out by using services.apache-kafka.configFiles.serverProperties
to the path of a fully rendered properties file.
Removal of services.apache-kafka.hostname
and services.apache-kafka.port
Translate using: services.apache-kafka.settings.listeners
Removal of services.apache-kafka.logDirs
Translate using: services.apache-kafka.settings."log.dirs"
Removal of services.apache-kafka.brokerId
Translate using: services.apache-kafka.settings."broker.id"
Removal of services.apache-kafka.zookeeper
Translate using: services.apache-kafka.settings."zookeeper.connect"
Table of Contents
Anki Sync Server is the built-in sync server, present in recent versions of Anki. Advanced users who cannot or do not wish to use AnkiWeb can use this sync server instead of AnkiWeb.
This module is compatible only with Anki versions >=2.1.66, due to recent enhancements to the Nix anki package.
By default, the module creates a
systemd
unit which runs the sync server with an isolated user using the systemd
DynamicUser
option.
This can be done by enabling the anki-sync-server
service:
{ ... }:
{
services.anki-sync-server.enable = true;
}
It is necessary to set at least one username-password pair under
services.anki-sync-server.users
. For example
{
services.anki-sync-server.users = [
{
username = "user";
passwordFile = /etc/anki-sync-server/user;
}
];
}
Here, passwordFile
is the path to a file containing just the password in
plaintext. Make sure to set permissions to make this file unreadable to any
user besides root.
By default, the server listen address services.anki-sync-server.host
is set to localhost, listening on port
services.anki-sync-server.port
, and does not open the firewall. This
is suitable for purely local testing, or to be used behind a reverse proxy. If
you want to expose the sync server directly to other computers (not recommended
in most circumstances, because the sync server doesn’t use HTTPS), then set the
following options:
{
services.anki-sync-server.host = "0.0.0.0";
services.anki-sync-server.openFirewall = true;
}
The ankisyncd
NixOS
module
provides similar functionality, but using a third-party implementation,
anki-sync-server-rs
.
According to that project’s README, it is “no longer maintained”, and not
recommended for Anki 2.1.64+.
Table of Contents
Matrix is an open standard for interoperable, decentralised, real-time communication over IP. It can be used to power Instant Messaging, VoIP/WebRTC signalling, Internet of Things communication - or anywhere you need a standard HTTP API for publishing and subscribing to data whilst tracking the conversation history.
This chapter will show you how to set up your own, self-hosted Matrix homeserver using the Synapse reference homeserver, and how to serve your own copy of the Element web client. See the Try Matrix Now! overview page for links to Element Apps for Android and iOS, desktop clients, as well as bridges to other networks and other projects around Matrix.
Synapse is the reference homeserver implementation of Matrix from the core development team at matrix.org.
Before deploying synapse server, a postgresql database must be set up.
For that, please make sure that postgresql is running and the following
SQL statements to create a user & database called matrix-synapse
were
executed before synapse starts up:
CREATE ROLE "matrix-synapse";
CREATE DATABASE "matrix-synapse" WITH OWNER "matrix-synapse"
TEMPLATE template0
LC_COLLATE = "C"
LC_CTYPE = "C";
Usually, it’s sufficient to do this once manually before continuing with the installation.
Please make sure to set a different password.
The following configuration example will set up a
synapse server for the example.org
domain, served from
the host myhostname.example.org
. For more information,
please refer to the
installation instructions of Synapse .
{ pkgs, lib, config, ... }:
let
fqdn = "${config.networking.hostName}.${config.networking.domain}";
baseUrl = "https://${fqdn}";
clientConfig."m.homeserver".base_url = baseUrl;
serverConfig."m.server" = "${fqdn}:443";
mkWellKnown = data: ''
default_type application/json;
add_header Access-Control-Allow-Origin *;
return 200 '${builtins.toJSON data}';
'';
in {
networking.hostName = "myhostname";
networking.domain = "example.org";
networking.firewall.allowedTCPPorts = [ 80 443 ];
services.postgresql.enable = true;
services.nginx = {
enable = true;
recommendedTlsSettings = true;
recommendedOptimisation = true;
recommendedGzipSettings = true;
recommendedProxySettings = true;
virtualHosts = {
# If the A and AAAA DNS records on example.org do not point on the same host as the
# records for myhostname.example.org, you can easily move the /.well-known
# virtualHost section of the code to the host that is serving example.org, while
# the rest stays on myhostname.example.org with no other changes required.
# This pattern also allows to seamlessly move the homeserver from
# myhostname.example.org to myotherhost.example.org by only changing the
# /.well-known redirection target.
"${config.networking.domain}" = {
enableACME = true;
forceSSL = true;
# This section is not needed if the server_name of matrix-synapse is equal to
# the domain (i.e. example.org from @foo:example.org) and the federation port
# is 8448.
# Further reference can be found in the docs about delegation under
# https://element-hq.github.io/synapse/latest/delegate.html
locations."= /.well-known/matrix/server".extraConfig = mkWellKnown serverConfig;
# This is usually needed for homeserver discovery (from e.g. other Matrix clients).
# Further reference can be found in the upstream docs at
# https://spec.matrix.org/latest/client-server-api/#getwell-knownmatrixclient
locations."= /.well-known/matrix/client".extraConfig = mkWellKnown clientConfig;
};
"${fqdn}" = {
enableACME = true;
forceSSL = true;
# It's also possible to do a redirect here or something else, this vhost is not
# needed for Matrix. It's recommended though to *not put* element
# here, see also the section about Element.
locations."/".extraConfig = ''
return 404;
'';
# Forward all Matrix API calls to the synapse Matrix homeserver. A trailing slash
# *must not* be used here.
locations."/_matrix".proxyPass = "http://[::1]:8008";
# Forward requests for e.g. SSO and password-resets.
locations."/_synapse/client".proxyPass = "http://[::1]:8008";
};
};
};
services.matrix-synapse = {
enable = true;
settings.server_name = config.networking.domain;
# The public base URL value must match the `base_url` value set in `clientConfig` above.
# The default value here is based on `server_name`, so if your `server_name` is different
# from the value of `fqdn` above, you will likely run into some mismatched domain names
# in client applications.
settings.public_baseurl = baseUrl;
settings.listeners = [
{ port = 8008;
bind_addresses = [ "::1" ];
type = "http";
tls = false;
x_forwarded = true;
resources = [ {
names = [ "client" "federation" ];
compress = true;
} ];
}
];
};
}
If you want to run a server with public registration by anybody, you can
then enable services.matrix-synapse.settings.enable_registration = true;
.
Otherwise, or you can generate a registration secret with
pwgen -s 64 1 and set it with
services.matrix-synapse.settings.registration_shared_secret
.
To create a new user or admin from the terminal your client listener
must be configured to use TCP sockets. Then you can run the following
after you have set the secret and have rebuilt NixOS:
$ nix-shell -p matrix-synapse
$ register_new_matrix_user -k your-registration-shared-secret http://localhost:8008
New user localpart: your-username
Password:
Confirm password:
Make admin [no]:
Success!
In the example, this would create a user with the Matrix Identifier
@your-username:example.org
.
When using services.matrix-synapse.settings.registration_shared_secret
, the secret
will end up in the world-readable store. Instead it’s recommended to deploy the secret
in an additional file like this:
Create a file with the following contents:
registration_shared_secret: your-very-secret-secret
Deploy the file with a secret-manager such as
deployment.keys
from nixops(1) or sops-nix to
e.g. /run/secrets/matrix-shared-secret
and ensure that it’s readable
by matrix-synapse
.
Include the file like this in your configuration:
{
services.matrix-synapse.extraConfigFiles = [
"/run/secrets/matrix-shared-secret"
];
}
It’s also possible to user alternative authentication mechanism such as
LDAP (via matrix-synapse-ldap3
)
or OpenID.
Element Web is
the reference web client for Matrix and developed by the core team at
matrix.org. Element was formerly known as Riot.im, see the
Element introductory blog post
for more information. The following snippet can be optionally added to the code before
to complete the synapse installation with a web client served at
https://element.myhostname.example.org
and
https://element.example.org
. Alternatively, you can use the hosted
copy at https://app.element.io/,
or use other web clients or native client applications. Due to the
/.well-known
urls set up done above, many clients should
fill in the required connection details automatically when you enter your
Matrix Identifier. See
Try Matrix Now!
for a list of existing clients and their supported featureset.
{
services.nginx.virtualHosts."element.${fqdn}" = {
enableACME = true;
forceSSL = true;
serverAliases = [
"element.${config.networking.domain}"
];
root = pkgs.element-web.override {
conf = {
default_server_config = clientConfig; # see `clientConfig` from the snippet above.
};
};
};
}
The Element developers do not recommend running Element and your Matrix
homeserver on the same fully-qualified domain name for security reasons. In
the example, this means that you should not reuse the
myhostname.example.org
virtualHost to also serve Element,
but instead serve it on a different subdomain, like
element.example.org
in the example. See the
Element Important Security Notes
for more information on this subject.
Table of Contents
This chapter will show you how to set up your own, self-hosted Mjolnir instance.
As an all-in-one moderation tool, it can protect your server from malicious invites, spam messages, and whatever else you don’t want. In addition to server-level protection, Mjolnir is great for communities wanting to protect their rooms without having to use their personal accounts for moderation.
The bot by default includes support for bans, redactions, anti-spam, server ACLs, room directory changes, room alias transfers, account deactivation, room shutdown, and more.
See the README page and the Moderator’s guide for additional instructions on how to setup and use Mjolnir.
For additional settings see the default configuration.
First create a new Room which will be used as a management room for Mjolnir. In this room, Mjolnir will log possible errors and debugging information. You’ll need to set this Room-ID in services.mjolnir.managementRoom.
Next, create a new user for Mjolnir on your homeserver, if not present already.
The Mjolnir Matrix user expects to be free of any rate limiting. See Synapse #6286 for an example on how to achieve this.
If you want Mjolnir to be able to deactivate users, move room aliases, shutdown rooms, etc. you’ll need to make the Mjolnir user a Matrix server admin.
Now invite the Mjolnir user to the management room.
It is recommended to use Pantalaimon, so your management room can be encrypted. This also applies if you are looking to moderate an encrypted room.
To enable the Pantalaimon E2E Proxy for mjolnir, enable services.mjolnir.pantalaimon. This will autoconfigure a new Pantalaimon instance, which will connect to the homeserver set in services.mjolnir.homeserverUrl and Mjolnir itself will be configured to connect to the new Pantalaimon instance.
{
services.mjolnir = {
enable = true;
homeserverUrl = "https://matrix.domain.tld";
pantalaimon = {
enable = true;
username = "mjolnir";
passwordFile = "/run/secrets/mjolnir-password";
};
protectedRooms = [
"https://matrix.to/#/!xxx:domain.tld"
];
managementRoom = "!yyy:domain.tld";
};
}
If you are using a managed “Element Matrix Services (EMS)” server, you will need to consent to the terms and conditions. Upon startup, an error log entry with a URL to the consent page will be generated.
A Synapse module is also available to apply the same rulesets the bot uses across an entire homeserver.
To use the Antispam Module, add matrix-synapse-plugins.matrix-synapse-mjolnir-antispam
to the Synapse plugin list and enable the mjolnir.Module
module.
{
services.matrix-synapse = {
plugins = with pkgs; [
matrix-synapse-plugins.matrix-synapse-mjolnir-antispam
];
extraConfig = ''
modules:
- module: mjolnir.Module
config:
# Prevent servers/users in the ban lists from inviting users on this
# server to rooms. Default true.
block_invites: true
# Flag messages sent by servers/users in the ban lists as spam. Currently
# this means that spammy messages will appear as empty to users. Default
# false.
block_messages: false
# Remove users from the user directory search by filtering matrix IDs and
# display names by the entries in the user ban list. Default false.
block_usernames: false
# The room IDs of the ban lists to honour. Unlike other parts of Mjolnir,
# this list cannot be room aliases or permalinks. This server is expected
# to already be joined to the room - Mjolnir will not automatically join
# these rooms.
ban_lists:
- "!roomid:example.org"
'';
};
}
Table of Contents
Maubot is a plugin-based bot framework for Matrix.
Set services.maubot.enable
to true
. The service will use
SQLite by default.
If you want to use PostgreSQL instead of SQLite, do this:
{
services.maubot.settings.database = "postgresql://maubot@localhost/maubot";
}
If the PostgreSQL connection requires a password, you will have to add it later on step 8.
If you plan to expose your Maubot interface to the web, do something like this:
{
services.nginx.virtualHosts."matrix.example.org".locations = {
"/_matrix/maubot/" = {
proxyPass = "http://127.0.0.1:${toString config.services.maubot.settings.server.port}";
proxyWebsockets = true;
};
};
services.maubot.settings.server.public_url = "matrix.example.org";
# do the following only if you want to use something other than /_matrix/maubot...
services.maubot.settings.server.ui_base_path = "/another/base/path";
}
Optionally, set services.maubot.pythonPackages
to a list of python3
packages to make available for Maubot plugins.
Optionally, set services.maubot.plugins
to a list of Maubot
plugins (full list available at https://plugins.maubot.xyz/):
{
services.maubot.plugins = with config.services.maubot.package.plugins; [
reactbot
# This will only change the default config! After you create a
# plugin instance, the default config will be copied into that
# instance's config in Maubot's database, and further base config
# changes won't affect the running plugin.
(rss.override {
base_config = {
update_interval = 60;
max_backoff = 7200;
spam_sleep = 2;
command_prefix = "rss";
admins = [ "@chayleaf:pavluk.org" ];
};
})
];
# ...or...
services.maubot.plugins = config.services.maubot.package.plugins.allOfficialPlugins;
# ...or...
services.maubot.plugins = config.services.maubot.package.plugins.allPlugins;
# ...or...
services.maubot.plugins = with config.services.maubot.package.plugins; [
(weather.override {
# you can pass base_config as a string
base_config = ''
default_location: New York
default_units: M
default_language:
show_link: true
show_image: false
'';
})
];
}
Start Maubot at least once before doing the following steps (it’s necessary to generate the initial config).
If your PostgreSQL connection requires a password, add
database: postgresql://user:password@localhost/maubot
to /var/lib/maubot/config.yaml
. This overrides the Nix-provided
config. Even then, don’t remove the database
line from Nix config
so the module knows you use PostgreSQL!
To create a user account for logging into Maubot web UI and
configuring it, generate a password using the shell command
mkpasswd -R 12 -m bcrypt
, and edit /var/lib/maubot/config.yaml
with the following:
admins:
admin_username: $2b$12$g.oIStUeUCvI58ebYoVMtO/vb9QZJo81PsmVOomHiNCFbh0dJpZVa
Where admin_username
is your username, and $2b...
is the bcrypted
password.
Optional: if you want to be able to register new users with the
Maubot CLI (mbc
), and your homeserver is private, add your
homeserver’s registration key to /var/lib/maubot/config.yaml
:
homeservers:
matrix.example.org:
url: https://matrix.example.org
secret: your-very-secret-key
Restart Maubot after editing /var/lib/maubot/config.yaml
,and
Maubot will be available at
https://matrix.example.org/_matrix/maubot
. If you want to use the
mbc
CLI, it’s available using the maubot
package (nix-shell -p maubot
).
Table of Contents
Mailman is free software for managing electronic mail discussion and e-newsletter lists. Mailman and its web interface can be configured using the corresponding NixOS module. Note that this service is best used with an existing, securely configured Postfix setup, as it does not automatically configure this.
For a basic configuration with Postfix as the MTA, the following settings are suggested:
{ config, ... }: {
services.postfix = {
enable = true;
relayDomains = ["hash:/var/lib/mailman/data/postfix_domains"];
sslCert = config.security.acme.certs."lists.example.org".directory + "/full.pem";
sslKey = config.security.acme.certs."lists.example.org".directory + "/key.pem";
config = {
transport_maps = ["hash:/var/lib/mailman/data/postfix_lmtp"];
local_recipient_maps = ["hash:/var/lib/mailman/data/postfix_lmtp"];
};
};
services.mailman = {
enable = true;
serve.enable = true;
hyperkitty.enable = true;
webHosts = ["lists.example.org"];
siteOwner = "mailman@example.org";
};
services.nginx.virtualHosts."lists.example.org".enableACME = true;
networking.firewall.allowedTCPPorts = [ 25 80 443 ];
}
DNS records will also be required:
AAAA
and A
records pointing to the host in question, in order for browsers to be able to discover the address of the web server;
An MX
record pointing to a domain name at which the host is reachable, in order for other mail servers to be able to deliver emails to the mailing lists it hosts.
After this has been done and appropriate DNS records have been set up, the Postorius mailing list manager and the Hyperkitty archive browser will be available at https://lists.example.org/. Note that this setup is not sufficient to deliver emails to most email providers nor to avoid spam – a number of additional measures for authenticating incoming and outgoing mails, such as SPF, DMARC and DKIM are necessary, but outside the scope of the Mailman module.
Mailman also supports other MTA, though with a little bit more configuration. For example, to use Mailman with Exim, you can use the following settings:
{ config, ... }: {
services = {
mailman = {
enable = true;
siteOwner = "mailman@example.org";
enablePostfix = false;
settings.mta = {
incoming = "mailman.mta.exim4.LMTP";
outgoing = "mailman.mta.deliver.deliver";
lmtp_host = "localhost";
lmtp_port = "8024";
smtp_host = "localhost";
smtp_port = "25";
configuration = "python:mailman.config.exim4";
};
};
exim = {
enable = true;
# You can configure Exim in a separate file to reduce configuration.nix clutter
config = builtins.readFile ./exim.conf;
};
};
}
The exim config needs some special additions to work with Mailman. Currently NixOS can’t manage Exim config with such granularity. Please refer to Mailman documentation for more info on configuring Mailman for working with Exim.
Trezor is an open-source cryptocurrency hardware wallet and security token allowing secure storage of private keys.
It offers advanced features such U2F two-factor authorization, SSH login through Trezor SSH agent, GPG and a password manager. For more information, guides and documentation, see https://wiki.trezor.io.
To enable Trezor support, add the following to your configuration.nix
:
services.trezord.enable = true;
This will add all necessary udev rules and start Trezor Bridge.
Table of Contents
Emacs is an extensible, customizable, self-documenting real-time display editor — and more. At its core is an interpreter for Emacs Lisp, a dialect of the Lisp programming language with extensions to support text editing.
Emacs runs within a graphical desktop environment using the X Window System, but works equally well on a text terminal. Under macOS, a “Mac port” edition is available, which uses Apple’s native GUI frameworks.
Nixpkgs provides a superior environment for running Emacs. It’s simple to create custom builds by overriding the default packages. Chaotic collections of Emacs Lisp code and extensions can be brought under control using declarative package management. NixOS even provides a systemd user service for automatically starting the Emacs daemon.
Emacs can be installed in the normal way for Nix (see Package Management). In addition, a NixOS service can be enabled.
Nixpkgs defines several basic Emacs packages.
The following are attributes belonging to the pkgs
set:
emacs
The latest stable version of Emacs using the GTK 2 widget toolkit.
emacs-nox
Emacs built without any dependency on X11 libraries.
emacsMacport
Emacs with the “Mac port” patches, providing a more native look and feel under macOS.
If those aren’t suitable, then the following imitation Emacs editors are also available in Nixpkgs: Zile, mg, Yi, jmacs.
Emacs includes an entire ecosystem of functionality beyond text editing, including a project planner, mail and news reader, debugger interface, calendar, and more.
Most extensions are gotten with the Emacs packaging system
(package.el
) from
Emacs Lisp Package Archive (ELPA),
MELPA,
MELPA Stable, and
Org ELPA. Nixpkgs is
regularly updated to mirror all these archives.
Under NixOS, you can continue to use
package-list-packages
and
package-install
to install packages. You can also
declare the set of Emacs packages you need using the derivations from
Nixpkgs. The rest of this section discusses declarative installation of
Emacs packages through nixpkgs.
The first step to declare the list of packages you want in your Emacs
installation is to create a dedicated derivation. This can be done in a
dedicated emacs.nix
file such as:
emacs.nix
)/*
This is a nix expression to build Emacs and some Emacs packages I like
from source on any distribution where Nix is installed. This will install
all the dependencies from the nixpkgs repository and build the binary files
without interfering with the host distribution.
To build the project, type the following from the current directory:
$ nix-build emacs.nix
To run the newly compiled executable:
$ ./result/bin/emacs
*/
# The first non-comment line in this file indicates that
# the whole file represents a function.
{ pkgs ? import <nixpkgs> {} }:
let
# The let expression below defines a myEmacs binding pointing to the
# current stable version of Emacs. This binding is here to separate
# the choice of the Emacs binary from the specification of the
# required packages.
myEmacs = pkgs.emacs;
# This generates an emacsWithPackages function. It takes a single
# argument: a function from a package set to a list of packages
# (the packages that will be available in Emacs).
emacsWithPackages = (pkgs.emacsPackagesFor myEmacs).emacsWithPackages;
in
# The rest of the file specifies the list of packages to install. In the
# example, two packages (magit and zerodark-theme) are taken from
# MELPA stable.
emacsWithPackages (epkgs: (with epkgs.melpaStablePackages; [
magit # ; Integrate git <C-x g>
zerodark-theme # ; Nicolas' theme
])
# Two packages (undo-tree and zoom-frm) are taken from MELPA.
++ (with epkgs.melpaPackages; [
undo-tree # ; <C-x u> to show the undo tree
zoom-frm # ; increase/decrease font size for all buffers %lt;C-x C-+>
])
# Three packages are taken from GNU ELPA.
++ (with epkgs.elpaPackages; [
auctex # ; LaTeX mode
beacon # ; highlight my cursor when scrolling
nameless # ; hide current package name everywhere in elisp code
])
# notmuch is taken from a nixpkgs derivation which contains an Emacs mode.
++ [
pkgs.notmuch # From main packages set
])
The result of this configuration will be an emacs
command which launches Emacs with all of your chosen packages in the
load-path
.
You can check that it works by executing this in a terminal:
$ nix-build emacs.nix
$ ./result/bin/emacs -q
and then typing M-x package-initialize
. Check that you
can use all the packages you want in this Emacs instance. For example, try
switching to the zerodark theme through M-x load-theme <RET> zerodark <RET> y
.
A few popular extensions worth checking out are: auctex, company, edit-server, flycheck, helm, iedit, magit, multiple-cursors, projectile, and yasnippet.
The list of available packages in the various ELPA repositories can be seen with the following commands:
nix-env -f "<nixpkgs>" -qaP -A emacs.pkgs.elpaPackages
nix-env -f "<nixpkgs>" -qaP -A emacs.pkgs.melpaPackages
nix-env -f "<nixpkgs>" -qaP -A emacs.pkgs.melpaStablePackages
nix-env -f "<nixpkgs>" -qaP -A emacs.pkgs.orgPackages
If you are on NixOS, you can install this particular Emacs for all users by
putting the emacs.nix
file in /etc/nixos
and adding it to the list of
system packages (see the section called “Declarative Package Management”). Simply modify your
file configuration.nix
to make it contain:
configuration.nix
{
environment.systemPackages = [
# [...]
(import ./emacs.nix { inherit pkgs; })
];
}
In this case, the next nixos-rebuild switch will take
care of adding your emacs to the PATH
environment variable (see Changing the Configuration).
If you are not on NixOS or want to install this particular Emacs only for
yourself, you can do so by putting emacs.nix
in ~/.config/nixpkgs
and
adding it to your ~/.config/nixpkgs/config.nix
(see
Nixpkgs manual):
~/.config/nixpkgs/config.nix
{
packageOverrides = super: let self = super.pkgs; in {
myemacs = import ./emacs.nix { pkgs = self; };
};
}
In this case, the next nix-env -f '<nixpkgs>' -iA myemacs
will take care of adding your emacs to the
PATH
environment variable.
If you want, you can tweak the Emacs package itself from your
emacs.nix
. For example, if you want to have a
GTK 3-based Emacs instead of the default GTK 2-based binary and remove the
automatically generated emacs.desktop
(useful if you
only use emacsclient), you can change your file
emacs.nix
in this way:
{ pkgs ? import <nixpkgs> {} }:
let
myEmacs = (pkgs.emacs.override {
# Use gtk3 instead of the default gtk2
withGTK3 = true;
withGTK2 = false;
}).overrideAttrs (attrs: {
# I don't want emacs.desktop file because I only use
# emacsclient.
postInstall = (attrs.postInstall or "") + ''
rm $out/share/applications/emacs.desktop
'';
});
in [ /* ... */ ]
After building this file as shown in Example 6, you will get an GTK 3-based Emacs binary pre-loaded with your favorite packages.
NixOS provides an optional systemd service which launches Emacs daemon with the user’s login session.
Source: modules/services/editors/emacs.nix
To install and enable the systemd user service for Emacs
daemon, add the following to your configuration.nix
:
{
services.emacs.enable = true;
}
The services.emacs.package
option allows a custom
derivation to be used, for example, one created by
emacsWithPackages
.
Ensure that the Emacs server is enabled for your user’s Emacs
configuration, either by customizing the server-mode
variable, or by adding (server-start)
to
~/.emacs.d/init.el
.
To start the daemon, execute the following:
$ nixos-rebuild switch # to activate the new configuration.nix
$ systemctl --user daemon-reload # to force systemd reload
$ systemctl --user start emacs.service # to start the Emacs daemon
The server should now be ready to serve Emacs clients.
Ensure that the Emacs server is enabled, either by customizing the
server-mode
variable, or by adding
(server-start)
to ~/.emacs
.
To connect to the Emacs daemon, run one of the following:
emacsclient FILENAME
emacsclient --create-frame # opens a new frame (window)
emacsclient --create-frame --tty # opens a new frame on the current terminal
EDITOR
variable If services.emacs.defaultEditor
is
true
, the EDITOR
variable will be set
to a wrapper script which launches emacsclient.
Any setting of EDITOR
in the shell config files will
override services.emacs.defaultEditor
. To make sure
EDITOR
refers to the Emacs wrapper script, remove any
existing EDITOR
assignment from
.profile
, .bashrc
,
.zshenv
or any other shell config file.
If you have formed certain bad habits when editing files, these can be corrected with a shell alias to the wrapper script:
alias vi=$EDITOR
In general, systemd user services are globally enabled
by symlinks in /etc/systemd/user
. In the case where
Emacs daemon is not wanted for all users, it is possible to install the
service but not globally enable it:
{
services.emacs.enable = false;
services.emacs.install = true;
}
To enable the systemd user service for just the currently logged in user, run:
systemctl --user enable emacs
This will add the symlink
~/.config/systemd/user/emacs.service
.
If you want to only use extension packages from Nixpkgs, you can add
(setq package-archives nil)
to your init file.
After the declarative Emacs package configuration has been tested,
previously downloaded packages can be cleaned up by removing
~/.emacs.d/elpa
(do make a backup first, in case you
forgot a package).
Of interest may be melpaPackages.nix-mode
, which
provides syntax highlighting for the Nix language. This is particularly
convenient if you regularly edit Nix files.
You can use woman
to get completion of all available
man pages. For example, type M-x woman <RET> nixos-rebuild <RET>.
Table of Contents
Livebook is a web application for writing interactive and collaborative code notebooks.
Enabling the livebook
service creates a user
systemd
unit
which runs the server.
{ ... }:
{
services.livebook = {
enableUserService = true;
environment = {
LIVEBOOK_PORT = 20123;
LIVEBOOK_PASSWORD = "mypassword";
};
# See note below about security
environmentFile = "/var/lib/livebook.env";
};
}
The Livebook server has the ability to run any command as the user it is running under, so securing access to it with a password is highly recommended.
Putting the password in the Nix configuration like above is an easy way to get
started but it is not recommended in the real world because the resulting
environment variables can be read by unprivileged users. A better approach
would be to put the password in some secure user-readable location and set
environmentFile = /home/user/secure/livebook.env
.
The Livebook
documentation
lists all the applicable environment variables. It is recommended to at least
set LIVEBOOK_PASSWORD
or LIVEBOOK_TOKEN_ENABLED=false
.
By default, the Livebook service is run with minimum dependencies, but
some features require additional packages. For example, the machine
learning Kinos require gcc
and gnumake
. To add these, use
extraPackages
:
{
services.livebook.extraPackages = with pkgs; [ gcc gnumake ];
}
Source: modules/services/development/blackfire.nix
Upstream documentation: https://blackfire.io/docs/introduction
Blackfire is a proprietary tool for profiling applications. There are several languages supported by the product but currently only PHP support is packaged in Nixpkgs. The back-end consists of a module that is loaded into the language runtime (called probe) and a service (agent) that the probe connects to and that sends the profiles to the server.
To use it, you will need to enable the agent and the probe on your server. The exact method will depend on the way you use PHP but here is an example of NixOS configuration for PHP-FPM:
let
php = pkgs.php.withExtensions ({ enabled, all }: enabled ++ (with all; [
blackfire
]));
in {
# Enable the probe extension for PHP-FPM.
services.phpfpm = {
phpPackage = php;
};
# Enable and configure the agent.
services.blackfire-agent = {
enable = true;
settings = {
# You will need to get credentials at https://blackfire.io/my/settings/credentials
# You can also use other options described in https://blackfire.io/docs/up-and-running/configuration/agent
server-id = "XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX";
server-token = "XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX";
};
};
# Make the agent run on start-up.
# (WantedBy= from the upstream unit not respected: https://github.com/NixOS/nixpkgs/issues/81138)
# Alternately, you can start it manually with `systemctl start blackfire-agent`.
systemd.services.blackfire-agent.wantedBy = [ "phpfpm-foo.service" ];
}
On your developer machine, you will also want to install the client (see blackfire
package) or the browser extension to actually trigger the profiling.
Table of Contents
Source: modules/services/development/athens.nix
Upstream documentation: https://docs.gomods.io/
Athens is a Go module datastore and proxy
The main goal of Athens is providing a Go proxy ($GOPROXY
) in regions without access to https://proxy.golang.org
or to
improve the speed of Go module downloads for CI/CD systems.
A complete list of options for the Athens module may be found here.
A very basic configuration for Athens that acts as a caching and forwarding HTTP proxy is:
{
services.athens = {
enable = true;
};
}
If you want to prevent Athens from writing to disk, you can instead configure it to cache modules only in memory:
{
services.athens = {
enable = true;
storageType = "memory";
};
}
To use the local proxy in Go builds, you can set the proxy as environment variable:
{
environment.variables = {
GOPROXY = "http://localhost:3000";
};
}
It is currently not possible to use the local proxy for builds done by the Nix daemon. This might be enabled
by experimental features, specifically configurable-impure-env
,
in upcoming Nix versions.
Source: modules/services/desktop/flatpak.nix
Upstream documentation: https://github.com/flatpak/flatpak/wiki
Flatpak is a system for building, distributing, and running sandboxed desktop applications on Linux.
To enable Flatpak, add the following to your configuration.nix
:
{
services.flatpak.enable = true;
}
For the sandboxed apps to work correctly, desktop integration portals need to
be installed. If you run GNOME, this will be handled automatically for you;
in other cases, you will need to add something like the following to your
configuration.nix
:
{
xdg.portal.extraPortals = [ pkgs.xdg-desktop-portal-gtk ];
xdg.portal.config.common.default = "gtk";
}
Then, you will need to add a repository, for example, Flathub, either using the following commands:
$ flatpak remote-add --if-not-exists flathub https://flathub.org/repo/flathub.flatpakrepo
$ flatpak update
or by opening the repository file in GNOME Software.
Finally, you can search and install programs:
$ flatpak search bustle
$ flatpak install flathub org.freedesktop.Bustle
$ flatpak run org.freedesktop.Bustle
Again, GNOME Software offers graphical interface for these tasks.
Table of Contents
Source: modules/services/databases/tigerbeetle.nix
Upstream documentation: https://docs.tigerbeetle.com/
TigerBeetle is a distributed financial accounting database designed for mission critical safety and performance.
To enable TigerBeetle, add the following to your configuration.nix
:
{
services.tigerbeetle.enable = true;
}
When first started, the TigerBeetle service will create its data file at /var/lib/tigerbeetle
unless the file already exists, in which case it will just use the existing file.
If you make changes to the configuration of TigerBeetle after its data file was already created (for example increasing the replica count), you may need to remove the existing file to avoid conflicts.
By default, TigerBeetle will only listen on a local interface.
To configure it to listen on a different interface (and to configure it to connect to other replicas, if you’re creating more than one), you’ll have to set the addresses
option.
Note that the TigerBeetle module won’t open any firewall ports automatically, so if you configure it to listen on an external interface, you’ll need to ensure that connections can reach it:
{
services.tigerbeetle = {
enable = true;
addresses = [ "0.0.0.0:3001" ];
};
networking.firewall.allowedTCPPorts = [ 3001 ];
}
A complete list of options for TigerBeetle can be found here.
Table of Contents
Source: modules/services/databases/postgresql.nix
Upstream documentation: https://www.postgresql.org/docs/
PostgreSQL is an advanced, free relational database.
To enable PostgreSQL, add the following to your configuration.nix
:
{
services.postgresql.enable = true;
services.postgresql.package = pkgs.postgresql_15;
}
Note that you are required to specify the desired version of PostgreSQL (e.g. pkgs.postgresql_15
). Since upgrading your PostgreSQL version requires a database dump and reload (see below), NixOS cannot provide a default value for services.postgresql.package
such as the most recent release of PostgreSQL.
By default, PostgreSQL stores its databases in /var/lib/postgresql/$psqlSchema
. You can override this using services.postgresql.dataDir
, e.g.
{
services.postgresql.dataDir = "/data/postgresql";
}
As of NixOS 23.11,
services.postgresql.ensureUsers.*.ensurePermissions
has been
deprecated, after a change to default permissions in PostgreSQL 15
invalidated most of its previous use cases:
In psql < 15, ALL PRIVILEGES
used to include CREATE TABLE
, where
in psql >= 15 that would be a separate permission
psql >= 15 instead gives only the database owner create permissions
Even on psql < 15 (or databases migrated to >= 15), it is recommended to manually assign permissions along these lines
https://www.postgresql.org/docs/release/15.0/
https://www.postgresql.org/docs/15/ddl-schemas.html#DDL-SCHEMAS-PRIV
Usually, the database owner should be a database user of the same
name. This can be done with
services.postgresql.ensureUsers.*.ensureDBOwnership = true;
.
If the database user name equals the connecting system user name, postgres by default will accept a passwordless connection via unix domain socket. This makes it possible to run many postgres-backed services without creating any database secrets at all
For many cases, it will be enough to have the database user be the
owner. Until services.postgresql.ensureUsers.*.ensurePermissions
has
been re-thought, if more users need access to the database, please use
one of the following approaches:
WARNING: services.postgresql.initialScript
is not recommended
for ensurePermissions
replacement, as that is only run on first
start of PostgreSQL.
NOTE: all of these methods may be obsoleted, when ensure*
is
reworked, but it is expected that they will stay viable for running
database migrations.
NOTE: please make sure that any added migrations are idempotent (re-runnable).
Advantage: compatible with postgres < 15, because it’s run
as the database superuser postgres
.
postStart
Disadvantage: need to take care of ordering yourself. In this
example, mkAfter
ensures that permissions are assigned after any
databases from ensureDatabases
and extraUser1
from ensureUsers
are already created.
{
systemd.services.postgresql.postStart = lib.mkAfter ''
$PSQL service1 -c 'GRANT SELECT ON ALL TABLES IN SCHEMA public TO "extraUser1"'
$PSQL service1 -c 'GRANT SELECT ON ALL SEQUENCES IN SCHEMA public TO "extraUser1"'
# ....
'';
}
{
systemd.services."migrate-service1-db1" = {
serviceConfig.Type = "oneshot";
requiredBy = "service1.service";
before = "service1.service";
after = "postgresql.service";
serviceConfig.User = "postgres";
environment.PSQL = "psql --port=${toString services.postgresql.settings.port}";
path = [ postgresql ];
script = ''
$PSQL service1 -c 'GRANT SELECT ON ALL TABLES IN SCHEMA public TO "extraUser1"'
$PSQL service1 -c 'GRANT SELECT ON ALL SEQUENCES IN SCHEMA public TO "extraUser1"'
# ....
'';
};
}
Advantage: re-uses systemd’s dependency ordering;
Disadvantage: relies on service user having grant permission. To be combined with ensureDBOwnership
.
preStart
{
environment.PSQL = "psql --port=${toString services.postgresql.settings.port}";
path = [ postgresql ];
systemd.services."service1".preStart = ''
$PSQL -c 'GRANT SELECT ON ALL TABLES IN SCHEMA public TO "extraUser1"'
$PSQL -c 'GRANT SELECT ON ALL SEQUENCES IN SCHEMA public TO "extraUser1"'
# ....
'';
}
{
systemd.services."migrate-service1-db1" = {
serviceConfig.Type = "oneshot";
requiredBy = "service1.service";
before = "service1.service";
after = "postgresql.service";
serviceConfig.User = "service1";
environment.PSQL = "psql --port=${toString services.postgresql.settings.port}";
path = [ postgresql ];
script = ''
$PSQL -c 'GRANT SELECT ON ALL TABLES IN SCHEMA public TO "extraUser1"'
$PSQL -c 'GRANT SELECT ON ALL SEQUENCES IN SCHEMA public TO "extraUser1"'
# ....
'';
};
}
The steps below demonstrate how to upgrade from an older version to pkgs.postgresql_13
.
These instructions are also applicable to other versions.
Major PostgreSQL upgrades require a downtime and a few imperative steps to be called. This is the case because
each major version has some internal changes in the databases’ state during major releases. Because of that,
NixOS places the state into /var/lib/postgresql/<version>
where each version
can be obtained like this:
$ nix-instantiate --eval -A postgresql_13.psqlSchema
"13"
For an upgrade, a script like this can be used to simplify the process:
{ config, pkgs, ... }:
{
environment.systemPackages = [
(let
# XXX specify the postgresql package you'd like to upgrade to.
# Do not forget to list the extensions you need.
newPostgres = pkgs.postgresql_13.withPackages (pp: [
# pp.plv8
]);
in pkgs.writeScriptBin "upgrade-pg-cluster" ''
set -eux
# XXX it's perhaps advisable to stop all services that depend on postgresql
systemctl stop postgresql
export NEWDATA="/var/lib/postgresql/${newPostgres.psqlSchema}"
export NEWBIN="${newPostgres}/bin"
export OLDDATA="${config.services.postgresql.dataDir}"
export OLDBIN="${config.services.postgresql.package}/bin"
install -d -m 0700 -o postgres -g postgres "$NEWDATA"
cd "$NEWDATA"
sudo -u postgres $NEWBIN/initdb -D "$NEWDATA"
sudo -u postgres $NEWBIN/pg_upgrade \
--old-datadir "$OLDDATA" --new-datadir "$NEWDATA" \
--old-bindir $OLDBIN --new-bindir $NEWBIN \
"$@"
'')
];
}
The upgrade process is:
Rebuild nixos configuration with the configuration above added to your configuration.nix
. Alternatively, add that into separate file and reference it in imports
list.
Login as root (sudo su -
)
Run upgrade-pg-cluster
. It will stop old postgresql, initialize a new one and migrate the old one to the new one. You may supply arguments like --jobs 4
and --link
to speedup migration process. See https://www.postgresql.org/docs/current/pgupgrade.html for details.
Change postgresql package in NixOS configuration to the one you were upgrading to via services.postgresql.package
. Rebuild NixOS. This should start new postgres using upgraded data directory and all services you stopped during the upgrade.
After the upgrade it’s advisable to analyze the new cluster.
For PostgreSQL ≥ 14, use the vacuumdb
command printed by the upgrades script.
For PostgreSQL < 14, run (as su -l postgres
in the services.postgresql.dataDir
, in this example /var/lib/postgresql/13
):
$ ./analyze_new_cluster.sh
The next step removes the old state-directory!
$ ./delete_old_cluster.sh
A complete list of options for the PostgreSQL module may be found here.
Plugins collection for each PostgreSQL version can be accessed with .pkgs
. For example, for pkgs.postgresql_15
package, its plugin collection is accessed by pkgs.postgresql_15.pkgs
:
$ nix repl '<nixpkgs>'
Loading '<nixpkgs>'...
Added 10574 variables.
nix-repl> postgresql_15.pkgs.<TAB><TAB>
postgresql_15.pkgs.cstore_fdw postgresql_15.pkgs.pg_repack
postgresql_15.pkgs.pg_auto_failover postgresql_15.pkgs.pg_safeupdate
postgresql_15.pkgs.pg_bigm postgresql_15.pkgs.pg_similarity
postgresql_15.pkgs.pg_cron postgresql_15.pkgs.pg_topn
postgresql_15.pkgs.pg_hll postgresql_15.pkgs.pgjwt
postgresql_15.pkgs.pg_partman postgresql_15.pkgs.pgroonga
...
To add plugins via NixOS configuration, set services.postgresql.extraPlugins
:
{
services.postgresql.package = pkgs.postgresql_12;
services.postgresql.extraPlugins = ps: with ps; [
pg_repack
postgis
];
}
You can build custom PostgreSQL-with-plugins (to be used outside of NixOS) using function .withPackages
. For example, creating a custom PostgreSQL package in an overlay can look like:
self: super: {
postgresql_custom = self.postgresql_12.withPackages (ps: [
ps.pg_repack
ps.postgis
]);
}
Here’s a recipe on how to override a particular plugin through an overlay:
self: super: {
postgresql_15 = super.postgresql_15// {
pkgs = super.postgresql_15.pkgs // {
pg_repack = super.postgresql_15.pkgs.pg_repack.overrideAttrs (_: {
name = "pg_repack-v20181024";
src = self.fetchzip {
url = "https://github.com/reorg/pg_repack/archive/923fa2f3c709a506e111cc963034bf2fd127aa00.tar.gz";
sha256 = "17k6hq9xaax87yz79j773qyigm4fwk8z4zh5cyp6z0sxnwfqxxw5";
};
});
};
};
}
JIT-support in the PostgreSQL package is disabled by default because of the ~300MiB closure-size increase from the LLVM dependency. It can be optionally enabled in PostgreSQL with the following config option:
{
services.postgresql.enableJIT = true;
}
This makes sure that the jit
-setting
is set to on
and a PostgreSQL package with JIT enabled is used. Further tweaking of the JIT compiler, e.g. setting a different
query cost threshold via jit_above_cost
can be done manually via services.postgresql.settings
.
The attribute-names of JIT-enabled PostgreSQL packages are suffixed with _jit
, i.e. for each pkgs.postgresql
(and pkgs.postgresql_<major>
) in nixpkgs
there’s also a pkgs.postgresql_jit
(and pkgs.postgresql_<major>_jit
).
Alternatively, a JIT-enabled variant can be derived from a given postgresql
package via postgresql.withJIT
.
This is also useful if it’s not clear which attribute from nixpkgs
was originally used (e.g. when working with
config.services.postgresql.package
or if the package was modified via an
overlay) since all modifications are propagated to withJIT
. I.e.
with import <nixpkgs> {
overlays = [
(self: super: {
postgresql = super.postgresql.overrideAttrs (_: { pname = "foobar"; });
})
];
};
postgresql.withJIT.pname
evaluates to "foobar"
.
Table of Contents
Source: modules/services/databases/foundationdb.nix
Upstream documentation: https://apple.github.io/foundationdb/
Maintainer: Austin Seipp
Available version(s): 7.1.x
FoundationDB (or “FDB”) is an open source, distributed, transactional key-value store.
To enable FoundationDB, add the following to your
configuration.nix
:
{
services.foundationdb.enable = true;
services.foundationdb.package = pkgs.foundationdb71; # FoundationDB 7.1.x
}
The services.foundationdb.package
option is required, and
must always be specified. Due to the fact FoundationDB network protocols and
on-disk storage formats may change between (major) versions, and upgrades
must be explicitly handled by the user, you must always manually specify
this yourself so that the NixOS module will use the proper version. Note
that minor, bugfix releases are always compatible.
After running nixos-rebuild, you can verify whether
FoundationDB is running by executing fdbcli (which is
added to environment.systemPackages
):
$ sudo -u foundationdb fdbcli
Using cluster file `/etc/foundationdb/fdb.cluster'.
The database is available.
Welcome to the fdbcli. For help, type `help'.
fdb> status
Using cluster file `/etc/foundationdb/fdb.cluster'.
Configuration:
Redundancy mode - single
Storage engine - memory
Coordinators - 1
Cluster:
FoundationDB processes - 1
Machines - 1
Memory availability - 5.4 GB per process on machine with least available
Fault Tolerance - 0 machines
Server time - 04/20/18 15:21:14
...
fdb>
You can also write programs using the available client libraries. For example, the following Python program can be run in order to grab the cluster status, as a quick example. (This example uses nix-shell shebang support to automatically supply the necessary Python modules).
a@link> cat fdb-status.py
#! /usr/bin/env nix-shell
#! nix-shell -i python -p python pythonPackages.foundationdb71
import fdb
import json
def main():
fdb.api_version(520)
db = fdb.open()
@fdb.transactional
def get_status(tr):
return str(tr['\xff\xff/status/json'])
obj = json.loads(get_status(db))
print('FoundationDB available: %s' % obj['client']['database_status']['available'])
if __name__ == "__main__":
main()
a@link> chmod +x fdb-status.py
a@link> ./fdb-status.py
FoundationDB available: True
a@link>
FoundationDB is run under the foundationdb user and group by default, but this may be changed in the NixOS configuration. The systemd unit foundationdb.service controls the fdbmonitor process.
By default, the NixOS module for FoundationDB creates a single SSD-storage based database for development and basic usage. This storage engine is designed for SSDs and will perform poorly on HDDs; however it can handle far more data than the alternative “memory” engine and is a better default choice for most deployments. (Note that you can change the storage backend on-the-fly for a given FoundationDB cluster using fdbcli.)
Furthermore, only 1 server process and 1 backup agent are started in the default configuration. See below for more on scaling to increase this.
FoundationDB stores all data for all server processes under
/var/lib/foundationdb
. You can override this using
services.foundationdb.dataDir
, e.g.
{
services.foundationdb.dataDir = "/data/fdb";
}
Similarly, logs are stored under /var/log/foundationdb
by default, and there is a corresponding
services.foundationdb.logDir
as well.
Scaling the number of server processes is quite easy; simply specify
services.foundationdb.serverProcesses
to be the number of
FoundationDB worker processes that should be started on the machine.
FoundationDB worker processes typically require 4GB of RAM per-process at minimum for good performance, so this option is set to 1 by default since the maximum amount of RAM is unknown. You’re advised to abide by this restriction, so pick a number of processes so that each has 4GB or more.
A similar option exists in order to scale backup agent processes,
services.foundationdb.backupProcesses
. Backup agents are
not as performance/RAM sensitive, so feel free to experiment with the number
of available backup processes.
FoundationDB on NixOS works similarly to other Linux systems, so this section will be brief. Please refer to the full FoundationDB documentation for more on clustering.
FoundationDB organizes clusters using a set of coordinators, which are just specially-designated worker processes. By default, every installation of FoundationDB on NixOS will start as its own individual cluster, with a single coordinator: the first worker process on localhost.
Coordinators are specified globally using the /etc/foundationdb/fdb.cluster file, which all servers and client applications will use to find and join coordinators. Note that this file can not be managed by NixOS so easily: FoundationDB is designed so that it will rewrite the file at runtime for all clients and nodes when cluster coordinators change, with clients transparently handling this without intervention. It is fundamentally a mutable file, and you should not try to manage it in any way in NixOS.
When dealing with a cluster, there are two main things you want to do:
Add a node to the cluster for storage/compute.
Promote an ordinary worker to a coordinator.
A node must already be a member of the cluster in order to properly be promoted to a coordinator, so you must always add it first if you wish to promote it.
To add a machine to a FoundationDB cluster:
Choose one of the servers to start as the initial coordinator.
Copy the /etc/foundationdb/fdb.cluster file from this server to all the other servers. Restart FoundationDB on all of these other servers, so they join the cluster.
All of these servers are now connected and working together in the cluster, under the chosen coordinator.
At this point, you can add as many nodes as you want by just repeating the above steps. By default there will still be a single coordinator: you can use fdbcli to change this and add new coordinators.
As a convenience, FoundationDB can automatically assign coordinators based on the redundancy mode you wish to achieve for the cluster. Once all the nodes have been joined, simply set the replication policy, and then issue the coordinators auto command
For example, assuming we have 3 nodes available, we can enable double redundancy mode, then auto-select coordinators. For double redundancy, 3 coordinators is ideal: therefore FoundationDB will make every node a coordinator automatically:
fdbcli> configure double ssd
fdbcli> coordinators auto
This will transparently update all the servers within seconds, and appropriately rewrite the fdb.cluster file, as well as informing all client processes to do the same.
By default, all clients must use the current fdb.cluster file to access a given FoundationDB cluster. This file is located by default in /etc/foundationdb/fdb.cluster on all machines with the FoundationDB service enabled, so you may copy the active one from your cluster to a new node in order to connect, if it is not part of the cluster.
By default, any user who can connect to a FoundationDB process with the correct cluster configuration can access anything. FoundationDB uses a pluggable design to transport security, and out of the box it supports a LibreSSL-based plugin for TLS support. This plugin not only does in-flight encryption, but also performs client authorization based on the given endpoint’s certificate chain. For example, a FoundationDB server may be configured to only accept client connections over TLS, where the client TLS certificate is from organization Acme Co in the Research and Development unit.
Configuring TLS with FoundationDB is done using the
services.foundationdb.tls
options in order to control the
peer verification string, as well as the certificate and its private key.
Note that the certificate and its private key must be accessible to the FoundationDB user account that the server runs under. These files are also NOT managed by NixOS, as putting them into the store may reveal private information.
After you have a key and certificate file in place, it is not enough to simply set the NixOS module options – you must also configure the fdb.cluster file to specify that a given set of coordinators use TLS. This is as simple as adding the suffix :tls to your cluster coordinator configuration, after the port number. For example, assuming you have a coordinator on localhost with the default configuration, simply specifying:
XXXXXX:XXXXXX@127.0.0.1:4500:tls
will configure all clients and server processes to use TLS from now on.
The usual rules for doing FoundationDB backups apply on NixOS as written in the FoundationDB manual. However, one important difference is the security profile for NixOS: by default, the foundationdb systemd unit uses Linux namespaces to restrict write access to the system, except for the log directory, data directory, and the /etc/foundationdb/ directory. This is enforced by default and cannot be disabled.
However, a side effect of this is that the fdbbackup command doesn’t work properly for local filesystem backups: FoundationDB uses a server process alongside the database processes to perform backups and copy the backups to the filesystem. As a result, this process is put under the restricted namespaces above: the backup process can only write to a limited number of paths.
In order to allow flexible backup locations on local disks, the FoundationDB
NixOS module supports a
services.foundationdb.extraReadWritePaths
option. This
option takes a list of paths, and adds them to the systemd unit, allowing
the processes inside the service to write (and read) the specified
directories.
For example, to create backups in /opt/fdb-backups, first set up the paths in the module options:
{
services.foundationdb.extraReadWritePaths = [ "/opt/fdb-backups" ];
}
Restart the FoundationDB service, and it will now be able to write to this directory (even if it does not yet exist.) Note: this path must exist before restarting the unit. Otherwise, systemd will not include it in the private FoundationDB namespace (and it will not add it dynamically at runtime).
You can now perform a backup:
$ sudo -u foundationdb fdbbackup start -t default -d file:///opt/fdb-backups
$ sudo -u foundationdb fdbbackup status -t default
The FoundationDB setup for NixOS should currently be considered beta. FoundationDB is not new software, but the NixOS compilation and integration has only undergone fairly basic testing of all the available functionality.
There is no way to specify individual parameters for individual fdbserver processes. Currently, all server processes inherit all the global fdbmonitor settings.
Ruby bindings are not currently installed.
Go bindings are not currently installed.
NixOS’s FoundationDB module allows you to configure all of the most relevant configuration options for fdbmonitor, matching it quite closely. A complete list of options for the FoundationDB module may be found here. You should also read the FoundationDB documentation as well.
FoundationDB is a complex piece of software, and requires careful administration to properly use. Full documentation for administration can be found here: https://apple.github.io/foundationdb/.
Table of Contents
Source: modules/services/backup/borgbackup.nix
Upstream documentation: https://borgbackup.readthedocs.io/
BorgBackup (short: Borg) is a deduplicating backup program. Optionally, it supports compression and authenticated encryption.
The main goal of Borg is to provide an efficient and secure way to backup data. The data deduplication technique used makes Borg suitable for daily backups since only changes are stored. The authenticated encryption technique makes it suitable for backups to not fully trusted targets.
A complete list of options for the Borgbase module may be found here.
A very basic configuration for backing up to a locally accessible directory is:
{
opt.services.borgbackup.jobs = {
rootBackup = {
paths = "/";
exclude = [ "/nix" "/path/to/local/repo" ];
repo = "/path/to/local/repo";
doInit = true;
encryption = {
mode = "repokey";
passphrase = "secret";
};
compression = "auto,lzma";
startAt = "weekly";
};
};
}
If you do not want the passphrase to be stored in the world-readable Nix store, use passCommand. You find an example below.
You should use a different SSH key for each repository you write to, because the specified keys are restricted to running borg serve and can only access this single repository. You need the output of the generate pub file.
# sudo ssh-keygen -N '' -t ed25519 -f /run/keys/id_ed25519_my_borg_repo
# cat /run/keys/id_ed25519_my_borg_repo
ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAID78zmOyA+5uPG4Ot0hfAy+sLDPU1L4AiIoRYEIVbbQ/ root@nixos
Add the following snippet to your NixOS configuration:
{
services.borgbackup.repos = {
my_borg_repo = {
authorizedKeys = [
"ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAID78zmOyA+5uPG4Ot0hfAy+sLDPU1L4AiIoRYEIVbbQ/ root@nixos"
] ;
path = "/var/lib/my_borg_repo" ;
};
};
}
The following NixOS snippet creates an hourly backup to the service
(on the host nixos) as created in the section above. We assume
that you have stored a secret passphrasse in the file
/run/keys/borgbackup_passphrase
, which should be only
accessible by root
{
services.borgbackup.jobs = {
backupToLocalServer = {
paths = [ "/etc/nixos" ];
doInit = true;
repo = "borg@nixos:." ;
encryption = {
mode = "repokey-blake2";
passCommand = "cat /run/keys/borgbackup_passphrase";
};
environment = { BORG_RSH = "ssh -i /run/keys/id_ed25519_my_borg_repo"; };
compression = "auto,lzma";
startAt = "hourly";
};
};
}
The following few commands (run as root) let you test your backup.
> nixos-rebuild switch
...restarting the following units: polkit.service
> systemctl restart borgbackup-job-backupToLocalServer
> sleep 10
> systemctl restart borgbackup-job-backupToLocalServer
> export BORG_PASSPHRASE=topSecrect
> borg list --rsh='ssh -i /run/keys/id_ed25519_my_borg_repo' borg@nixos:.
nixos-backupToLocalServer-2020-03-30T21:46:17 Mon, 2020-03-30 21:46:19 [84feb97710954931ca384182f5f3cb90665f35cef214760abd7350fb064786ac]
nixos-backupToLocalServer-2020-03-30T21:46:30 Mon, 2020-03-30 21:46:32 [e77321694ecd160ca2228611747c6ad1be177d6e0d894538898de7a2621b6e68]
Several companies offer (paid) hosting services for Borg repositories.
To backup your home directory to borgbase you have to:
Generate a SSH key without a password, to access the remote server. E.g.
sudo ssh-keygen -N '' -t ed25519 -f /run/keys/id_ed25519_borgbase
Create the repository on the server by following the instructions for your hosting server.
Initialize the repository on the server. Eg.
sudo borg init --encryption=repokey-blake2 \
--rsh "ssh -i /run/keys/id_ed25519_borgbase" \
zzz2aaaaa@zzz2aaaaa.repo.borgbase.com:repo
Add it to your NixOS configuration, e.g.
{
services.borgbackup.jobs = {
my_Remote_Backup = {
paths = [ "/" ];
exclude = [ "/nix" "'**/.cache'" ];
repo = "zzz2aaaaa@zzz2aaaaa.repo.borgbase.com:repo";
encryption = {
mode = "repokey-blake2";
passCommand = "cat /run/keys/borgbackup_passphrase";
};
environment = { BORG_RSH = "ssh -i /run/keys/id_ed25519_borgbase"; };
compression = "auto,lzma";
startAt = "daily";
};
};
}}
Vorta is a backup client for macOS and Linux desktops. It integrates the mighty BorgBackup with your desktop environment to protect your data from disk failure, ransomware and theft.
It can be installed in NixOS e.g. by adding pkgs.vorta
to environment.systemPackages
.
Details about using Vorta can be found under https://vorta.borgbase.com .
Table of Contents
NixOS supports automatic domain validation & certificate retrieval and renewal using the ACME protocol. Any provider can be used, but by default NixOS uses Let’s Encrypt. The alternative ACME client lego is used under the hood.
Automatic cert validation and configuration for Apache and Nginx virtual hosts is included in NixOS, however if you would like to generate a wildcard cert or you are not using a web server you will have to configure DNS based validation.
To use the ACME module, you must accept the provider’s terms of service
by setting security.acme.acceptTerms
to true
. The Let’s Encrypt ToS can be found
here.
You must also set an email address to be used when creating accounts with
Let’s Encrypt. You can set this for all certs with
security.acme.defaults.email
and/or on a per-cert basis with
security.acme.certs.<name>.email
.
This address is only used for registration and renewal reminders,
and cannot be used to administer the certificates in any way.
Alternatively, you can use a different ACME server by changing the
security.acme.defaults.server
option
to a provider of your choosing, or just change the server for one cert with
security.acme.certs.<name>.server
.
You will need an HTTP server or DNS server for verification. For HTTP,
the server must have a webroot defined that can serve
.well-known/acme-challenge
. This directory must be
writeable by the user that will run the ACME client. For DNS, you must
set up credentials with your provider/server for use with lego.
NixOS supports fetching ACME certificates for you by setting
enableACME = true;
in a virtualHost config. We first create self-signed
placeholder certificates in place of the real ACME certs. The placeholder
certs are overwritten when the ACME certs arrive. For
foo.example.com
the config would look like this:
{
security.acme.acceptTerms = true;
security.acme.defaults.email = "admin+acme@example.com";
services.nginx = {
enable = true;
virtualHosts = {
"foo.example.com" = {
forceSSL = true;
enableACME = true;
# All serverAliases will be added as extra domain names on the certificate.
serverAliases = [ "bar.example.com" ];
locations."/" = {
root = "/var/www";
};
};
# We can also add a different vhost and reuse the same certificate
# but we have to append extraDomainNames manually beforehand:
# security.acme.certs."foo.example.com".extraDomainNames = [ "baz.example.com" ];
"baz.example.com" = {
forceSSL = true;
useACMEHost = "foo.example.com";
locations."/" = {
root = "/var/www";
};
};
};
};
}
Using ACME certificates with Apache virtual hosts is identical to using them with Nginx. The attribute names are all the same, just replace “nginx” with “httpd” where appropriate.
First off you will need to set up a virtual host to serve the challenges.
This example uses a vhost called certs.example.com
, with
the intent that you will generate certs for all your vhosts and redirect
everyone to HTTPS.
{
security.acme.acceptTerms = true;
security.acme.defaults.email = "admin+acme@example.com";
# /var/lib/acme/.challenges must be writable by the ACME user
# and readable by the Nginx user. The easiest way to achieve
# this is to add the Nginx user to the ACME group.
users.users.nginx.extraGroups = [ "acme" ];
services.nginx = {
enable = true;
virtualHosts = {
"acmechallenge.example.com" = {
# Catchall vhost, will redirect users to HTTPS for all vhosts
serverAliases = [ "*.example.com" ];
locations."/.well-known/acme-challenge" = {
root = "/var/lib/acme/.challenges";
};
locations."/" = {
return = "301 https://$host$request_uri";
};
};
};
};
# Alternative config for Apache
users.users.wwwrun.extraGroups = [ "acme" ];
services.httpd = {
enable = true;
virtualHosts = {
"acmechallenge.example.com" = {
# Catchall vhost, will redirect users to HTTPS for all vhosts
serverAliases = [ "*.example.com" ];
# /var/lib/acme/.challenges must be writable by the ACME user and readable by the Apache user.
# By default, this is the case.
documentRoot = "/var/lib/acme/.challenges";
extraConfig = ''
RewriteEngine On
RewriteCond %{HTTPS} off
RewriteCond %{REQUEST_URI} !^/\.well-known/acme-challenge [NC]
RewriteRule (.*) https://%{HTTP_HOST}%{REQUEST_URI} [R=301]
'';
};
};
};
}
Now you need to configure ACME to generate a certificate.
{
security.acme.certs."foo.example.com" = {
webroot = "/var/lib/acme/.challenges";
email = "foo@example.com";
# Ensure that the web server you use can read the generated certs
# Take a look at the group option for the web server you choose.
group = "nginx";
# Since we have a wildcard vhost to handle port 80,
# we can generate certs for anything!
# Just make sure your DNS resolves them.
extraDomainNames = [ "mail.example.com" ];
};
}
The private key key.pem
and certificate
fullchain.pem
will be put into
/var/lib/acme/foo.example.com
.
Refer to Appendix A for all available configuration options for the security.acme module.
This is useful if you want to generate a wildcard certificate, since ACME servers will only hand out wildcard certs over DNS validation. There are a number of supported DNS providers and servers you can utilise, see the lego docs for provider/server specific configuration values. For the sake of these docs, we will provide a fully self-hosted example using bind.
{
services.bind = {
enable = true;
extraConfig = ''
include "/var/lib/secrets/dnskeys.conf";
'';
zones = [
rec {
name = "example.com";
file = "/var/db/bind/${name}";
master = true;
extraConfig = "allow-update { key rfc2136key.example.com.; };";
}
];
};
# Now we can configure ACME
security.acme.acceptTerms = true;
security.acme.defaults.email = "admin+acme@example.com";
security.acme.certs."example.com" = {
domain = "*.example.com";
dnsProvider = "rfc2136";
environmentFile = "/var/lib/secrets/certs.secret";
# We don't need to wait for propagation since this is a local DNS server
dnsPropagationCheck = false;
};
}
The dnskeys.conf
and certs.secret
must be kept secure and thus you should not keep their contents in your
Nix config. Instead, generate them one time with a systemd service:
{
systemd.services.dns-rfc2136-conf = {
requiredBy = ["acme-example.com.service" "bind.service"];
before = ["acme-example.com.service" "bind.service"];
unitConfig = {
ConditionPathExists = "!/var/lib/secrets/dnskeys.conf";
};
serviceConfig = {
Type = "oneshot";
UMask = 0077;
};
path = [ pkgs.bind ];
script = ''
mkdir -p /var/lib/secrets
chmod 755 /var/lib/secrets
tsig-keygen rfc2136key.example.com > /var/lib/secrets/dnskeys.conf
chown named:root /var/lib/secrets/dnskeys.conf
chmod 400 /var/lib/secrets/dnskeys.conf
# extract secret value from the dnskeys.conf
while read x y; do if [ "$x" = "secret" ]; then secret="''${y:1:''${#y}-3}"; fi; done < /var/lib/secrets/dnskeys.conf
cat > /var/lib/secrets/certs.secret << EOF
RFC2136_NAMESERVER='127.0.0.1:53'
RFC2136_TSIG_ALGORITHM='hmac-sha256.'
RFC2136_TSIG_KEY='rfc2136key.example.com'
RFC2136_TSIG_SECRET='$secret'
EOF
chmod 400 /var/lib/secrets/certs.secret
'';
};
}
Now you’re all set to generate certs! You should monitor the first invocation
by running systemctl start acme-example.com.service & journalctl -fu acme-example.com.service
and watching its log output.
It is possible to use DNS-01 validation with all certificates,
including those automatically configured via the Nginx/Apache
enableACME
option. This configuration pattern is fully
supported and part of the module’s test suite for Nginx + Apache.
You must follow the guide above on configuring DNS-01 validation
first, however instead of setting the options for one certificate
(e.g. security.acme.certs.<name>.dnsProvider
)
you will set them as defaults
(e.g. security.acme.defaults.dnsProvider
).
{
# Configure ACME appropriately
security.acme.acceptTerms = true;
security.acme.defaults.email = "admin+acme@example.com";
security.acme.defaults = {
dnsProvider = "rfc2136";
environmentFile = "/var/lib/secrets/certs.secret";
# We don't need to wait for propagation since this is a local DNS server
dnsPropagationCheck = false;
};
# For each virtual host you would like to use DNS-01 validation with,
# set acmeRoot = null
services.nginx = {
enable = true;
virtualHosts = {
"foo.example.com" = {
enableACME = true;
acmeRoot = null;
};
};
};
}
And that’s it! Next time your configuration is rebuilt, or when you add a new virtualHost, it will be DNS-01 validated.
Some services refuse to start if the configured certificate files
are not owned by root. PostgreSQL and OpenSMTPD are examples of these.
There is no way to change the user the ACME module uses (it will always be
acme
), however you can use systemd’s
LoadCredential
feature to resolve this elegantly.
Below is an example configuration for OpenSMTPD, but this pattern
can be applied to any service.
{
# Configure ACME however you like (DNS or HTTP validation), adding
# the following configuration for the relevant certificate.
# Note: You cannot use `systemctl reload` here as that would mean
# the LoadCredential configuration below would be skipped and
# the service would continue to use old certificates.
security.acme.certs."mail.example.com".postRun = ''
systemctl restart opensmtpd
'';
# Now you must augment OpenSMTPD's systemd service to load
# the certificate files.
systemd.services.opensmtpd.requires = ["acme-finished-mail.example.com.target"];
systemd.services.opensmtpd.serviceConfig.LoadCredential = let
certDir = config.security.acme.certs."mail.example.com".directory;
in [
"cert.pem:${certDir}/cert.pem"
"key.pem:${certDir}/key.pem"
];
# Finally, configure OpenSMTPD to use these certs.
services.opensmtpd = let
credsDir = "/run/credentials/opensmtpd.service";
in {
enable = true;
setSendmail = false;
serverConfiguration = ''
pki mail.example.com cert "${credsDir}/cert.pem"
pki mail.example.com key "${credsDir}/key.pem"
listen on localhost tls pki mail.example.com
action act1 relay host smtp://127.0.0.1:10027
match for local action act1
'';
};
}
Should you need to regenerate a particular certificate in a hurry, such
as when a vulnerability is found in Let’s Encrypt, there is now a convenient
mechanism for doing so. Running
systemctl clean --what=state acme-example.com.service
will remove all certificate files and the account data for the given domain,
allowing you to then systemctl start acme-example.com.service
to generate fresh ones.
It is possible that your account credentials file may become corrupt and need
to be regenerated. In this scenario lego will produce the error JWS verification error
.
The solution is to simply delete the associated accounts file and
re-run the affected service(s).
# Find the accounts folder for the certificate
systemctl cat acme-example.com.service | grep -Po 'accounts/[^:]*'
export accountdir="$(!!)"
# Move this folder to some place else
mv /var/lib/acme/.lego/$accountdir{,.bak}
# Recreate the folder using systemd-tmpfiles
systemd-tmpfiles --create
# Get a new account and reissue certificates
# Note: Do this for all certs that share the same account email address
systemctl start acme-example.com.service
Table of Contents
oh-my-zsh
is a framework to manage your ZSH
configuration including completion scripts for several CLI tools or custom
prompt themes.
The module uses the oh-my-zsh
package with all available
features. The initial setup using Nix expressions is fairly similar to the
configuration format of oh-my-zsh
.
{
programs.zsh.ohMyZsh = {
enable = true;
plugins = [ "git" "python" "man" ];
theme = "agnoster";
};
}
For a detailed explanation of these arguments please refer to the
oh-my-zsh
docs.
The expression generates the needed configuration and writes it into your
/etc/zshrc
.
Sometimes third-party or custom scripts such as a modified theme may be
needed. oh-my-zsh
provides the
ZSH_CUSTOM
environment variable for this which points to a directory with additional
scripts.
The module can do this as well:
{
programs.zsh.ohMyZsh.custom = "~/path/to/custom/scripts";
}
There are several extensions for oh-my-zsh
packaged in
nixpkgs
. One of them is
nix-zsh-completions
which bundles completion scripts and a plugin for oh-my-zsh
.
Rather than using a single mutable path for ZSH_CUSTOM
,
it’s also possible to generate this path from a list of Nix packages:
{ pkgs, ... }:
{
programs.zsh.ohMyZsh.customPkgs = [
pkgs.nix-zsh-completions
# and even more...
];
}
Internally a single store path will be created using
buildEnv
. Please refer to the docs of
buildEnv
for further reference.
Please keep in mind that this is not compatible with
programs.zsh.ohMyZsh.custom
as it requires an immutable
store path while custom
shall remain mutable! An
evaluation failure will be thrown if both custom
and
customPkgs
are set.
If third-party customizations (e.g. new themes) are supposed to be added to
oh-my-zsh
there are several pitfalls to keep in mind:
To comply with the default structure of ZSH
the entire
output needs to be written to $out/share/zsh.
Completion scripts are supposed to be stored at
$out/share/zsh/site-functions
. This directory is part of the
fpath
and the package should be compatible with pure ZSH
setups. The module will automatically link the contents of
site-functions
to completions directory in the proper
store path.
The plugins
directory needs the structure
pluginname/pluginname.plugin.zsh
as structured in the
upstream repo.
A derivation for oh-my-zsh
may look like this:
{ stdenv, fetchFromGitHub }:
stdenv.mkDerivation rec {
name = "exemplary-zsh-customization-${version}";
version = "1.0.0";
src = fetchFromGitHub {
# path to the upstream repository
};
dontBuild = true;
installPhase = ''
mkdir -p $out/share/zsh/site-functions
cp {themes,plugins} $out/share/zsh
cp completions $out/share/zsh/site-functions
'';
}
Source: modules/programs/plotinus.nix
Upstream documentation: https://github.com/p-e-w/plotinus
Plotinus is a searchable command palette in every modern GTK application.
When in a GTK 3 application and Plotinus is enabled, you can press
Ctrl+Shift+P
to open the command palette. The command
palette provides a searchable list of of all menu items in the application.
To enable Plotinus, add the following to your
configuration.nix
:
{
programs.plotinus.enable = true;
}
Digital Bitbox is a hardware wallet and second-factor authenticator.
The digitalbitbox
programs module may be installed by setting
programs.digitalbitbox
to true
in a manner similar to
{
programs.digitalbitbox.enable = true;
}
and bundles the digitalbitbox
package (see the section called “Package”),
which contains the dbb-app
and dbb-cli
binaries, along with the hardware
module (see the section called “Hardware”) which sets up the necessary
udev rules to access the device.
Enabling the digitalbitbox module is pretty much the easiest way to get a Digital Bitbox device working on your system.
For more information, see https://digitalbitbox.com/start_linux.
The binaries, dbb-app
(a GUI tool) and dbb-cli
(a CLI tool), are available
through the digitalbitbox
package which could be installed as follows:
{
environment.systemPackages = [
pkgs.digitalbitbox
];
}
The digitalbitbox hardware package enables the udev rules for Digital Bitbox devices and may be installed as follows:
{
hardware.digitalbitbox.enable = true;
}
In order to alter the udev rules, one may provide different values for the
udevRule51
and udevRule52
attributes by means of overriding as follows:
{
programs.digitalbitbox = {
enable = true;
package = pkgs.digitalbitbox.override {
udevRule51 = "something else";
};
};
}
Input methods are an operating system component that allows any data, such as keyboard strokes or mouse movements, to be received as input. In this way users can enter characters and symbols not found on their input devices. Using an input method is obligatory for any language that has more graphemes than there are keys on the keyboard.
The following input methods are available in NixOS:
IBus: The intelligent input bus.
Fcitx5: The next generation of fcitx, addons (including engines, dictionaries, skins) can be added using i18n.inputMethod.fcitx5.addons
.
Nabi: A Korean input method based on XIM.
Uim: The universal input method, is a library with a XIM bridge.
Hime: An extremely easy-to-use input method framework.
Kime: Korean IME
IBus is an Intelligent Input Bus. It provides full featured and user friendly input method user interface.
The following snippet can be used to configure IBus:
{
i18n.inputMethod = {
enabled = "ibus";
ibus.engines = with pkgs.ibus-engines; [ anthy hangul mozc ];
};
}
i18n.inputMethod.ibus.engines
is optional and can be used
to add extra IBus engines.
Available extra IBus engines are:
Anthy (ibus-engines.anthy
): Anthy is a system for
Japanese input method. It converts Hiragana text to Kana Kanji mixed text.
Hangul (ibus-engines.hangul
): Korean input method.
m17n (ibus-engines.m17n
): m17n is an input method that
uses input methods and corresponding icons in the m17n database.
mozc (ibus-engines.mozc
): A Japanese input method from
Google.
Table (ibus-engines.table
): An input method that load
tables of input methods.
table-others (ibus-engines.table-others
): Various
table-based input methods. To use this, and any other table-based input
methods, it must appear in the list of engines along with
table
. For example:
{
ibus.engines = with pkgs.ibus-engines; [ table table-others ];
}
To use any input method, the package must be added in the configuration, as
shown above, and also (after running nixos-rebuild
) the
input method must be added from IBus’ preference dialog.
If IBus works in some applications but not others, a likely cause of this
is that IBus is depending on a different version of glib
to what the applications are depending on. This can be checked by running
nix-store -q --requisites <path> | grep glib
,
where <path>
is the path of either IBus or an
application in the Nix store. The glib
packages must
match exactly. If they do not, uninstalling and reinstalling the
application is a likely fix.
Fcitx5 is an input method framework with extension support. It has three built-in Input Method Engine, Pinyin, QuWei and Table-based input methods.
The following snippet can be used to configure Fcitx:
{
i18n.inputMethod = {
enabled = "fcitx5";
fcitx5.addons = with pkgs; [ fcitx5-mozc fcitx5-hangul fcitx5-m17n ];
};
}
i18n.inputMethod.fcitx5.addons
is optional and can be
used to add extra Fcitx5 addons.
Available extra Fcitx5 addons are:
Anthy (fcitx5-anthy
): Anthy is a system for
Japanese input method. It converts Hiragana text to Kana Kanji mixed text.
Chewing (fcitx5-chewing
): Chewing is an
intelligent Zhuyin input method. It is one of the most popular input
methods among Traditional Chinese Unix users.
Hangul (fcitx5-hangul
): Korean input method.
Unikey (fcitx5-unikey
): Vietnamese input method.
m17n (fcitx5-m17n
): m17n is an input method that
uses input methods and corresponding icons in the m17n database.
mozc (fcitx5-mozc
): A Japanese input method from
Google.
table-others (fcitx5-table-other
): Various
table-based input methods.
chinese-addons (fcitx5-chinese-addons
): Various chinese input methods.
rime (fcitx5-rime
): RIME support for fcitx5.
Nabi is an easy to use Korean X input method. It allows you to enter phonetic Korean characters (hangul) and pictographic Korean characters (hanja).
The following snippet can be used to configure Nabi:
{
i18n.inputMethod = {
enabled = "nabi";
};
}
Uim (short for “universal input method”) is a multilingual input method framework. Applications can use it through so-called bridges.
The following snippet can be used to configure uim:
{
i18n.inputMethod = {
enabled = "uim";
};
}
Note: The i18n.inputMethod.uim.toolbar
option can be
used to choose uim toolbar.
Hime is an extremely easy-to-use input method framework. It is lightweight, stable, powerful and supports many commonly used input methods, including Cangjie, Zhuyin, Dayi, Rank, Shrimp, Greek, Korean Pinyin, Latin Alphabet, etc…
The following snippet can be used to configure Hime:
{
i18n.inputMethod = {
enabled = "hime";
};
}
Kime is Korean IME. it’s built with Rust language and let you get simple, safe, fast Korean typing
The following snippet can be used to configure Kime:
{
i18n.inputMethod = {
enabled = "kime";
};
}
Table of Contents
In some cases, it may be desirable to take advantage of commonly-used,
predefined configurations provided by nixpkgs, but different from those
that come as default. This is a role fulfilled by NixOS’s Profiles,
which come as files living in <nixpkgs/nixos/modules/profiles>
. That
is to say, expected usage is to add them to the imports list of your
/etc/configuration.nix
as such:
{
imports = [
<nixpkgs/nixos/modules/profiles/profile-name.nix>
];
}
Even if some of these profiles seem only useful in the context of install media, many are actually intended to be used in real installs.
What follows is a brief explanation on the purpose and use-case for each profile. Detailing each option configured by each one is out of scope.
Enables all hardware supported by NixOS: i.e., all firmware is included, and all devices from which one may boot are enabled in the initrd. Its primary use is in the NixOS installation CDs.
The enabled kernel modules include support for SATA and PATA, SCSI
(partially), USB, Firewire (untested), Virtio (QEMU, KVM, etc.), VMware, and
Hyper-V. Additionally, hardware.enableAllFirmware
is
enabled, and the firmware for the ZyDAS ZD1211 chipset is specifically
installed.
Defines the software packages included in the “minimal” installation CD. It installs several utilities useful in a simple recovery or install media, such as a text-mode web browser, and tools for manipulating block devices, networking, hardware diagnostics, and filesystems (with their respective kernel modules).
This profile is used in installer images. It provides an editable configuration.nix that imports all the modules that were also used when creating the image in the first place. As a result it allows users to edit and rebuild the live-system.
On images where the installation media also becomes an installation target,
copying over configuration.nix
should be disabled by
setting installer.cloneConfig
to false
.
For example, this is done in sd-image-aarch64-installer.nix
.
This profile just enables a demo
user, with password demo
, uid 1000
, wheel
group and
autologin in the SDDM display manager.
This is the profile from which the Docker images are generated. It prepares a
working system by importing the Minimal and
Clone Config profiles, and
setting appropriate configuration options that are useful inside a container
context, like boot.isContainer
.
Defines a NixOS configuration with the Plasma 5 desktop. It’s used by the graphical installation CD.
It sets services.xserver.enable
,
services.displayManager.sddm.enable
,
services.xserver.desktopManager.plasma5.enable
,
and services.libinput.enable
to true. It also
includes glxinfo and firefox in the system packages list.
A profile with most (vanilla) hardening options enabled by default, potentially at the cost of stability, features and performance.
This includes a hardened kernel, and limiting the system information
available to processes through the /sys
and
/proc
filesystems. It also disables the User Namespaces
feature of the kernel, which stops Nix from being able to build anything
(this particular setting can be overridden via
security.allowUserNamespaces
). See the
profile source
for further detail on which settings are altered.
This profile enables options that are known to affect system stability. If you experience any stability issues when using the profile, try disabling it. If you report an issue and use this profile, always mention that you do.
Common configuration for headless machines (e.g., Amazon EC2 instances).
Disables sound, vesa, serial consoles, emergency mode, grub splash images and configures the kernel to reboot automatically on panic.
Provides a basic configuration for installation devices like CDs.
This enables redistributable firmware, includes the
Clone Config profile
and a copy of the Nixpkgs channel, so nixos-install
works out of the box.
Documentation for Nixpkgs
and NixOS are
forcefully enabled (to override the
Minimal profile preference); the
NixOS manual is shown automatically on TTY 8, udisks is disabled.
Autologin is enabled as nixos
user, while passwordless
login as both root
and nixos
is possible.
Passwordless sudo
is enabled too.
wpa_supplicant is
enabled, but configured to not autostart.
It is explained how to login, start the ssh server, and if available, how to start the display manager.
Several settings are tweaked so that the installer has a better chance of succeeding under low-memory environments.
If you enable this profile, you will NOT be able to switch to a new configuration and thus you will not be able to rebuild your system with nixos-rebuild!
Render your system completely perlless (i.e. without the perl interpreter). This includes a mechanism so that your build fails if it contains a Nix store path that references the string “perl”.
This profile defines a small NixOS configuration. It does not contain any
graphical stuff. It’s a very short file that enables
noXlibs, sets
i18n.supportedLocales
to
only support the user-selected locale,
disables packages’ documentation,
and disables sound.
This profile contains common configuration for virtual machines running under QEMU (using virtio).
It makes virtio modules available on the initrd and sets the system time from the hardware clock to work around a bug in qemu-kvm.
The NixOS Kubernetes module is a collective term for a handful of individual submodules implementing the Kubernetes cluster components.
There are generally two ways of enabling Kubernetes on NixOS. One way is to enable and configure cluster components appropriately by hand:
{
services.kubernetes = {
apiserver.enable = true;
controllerManager.enable = true;
scheduler.enable = true;
addonManager.enable = true;
proxy.enable = true;
flannel.enable = true;
};
}
Another way is to assign cluster roles (“master” and/or “node”) to the host. This enables apiserver, controllerManager, scheduler, addonManager, kube-proxy and etcd:
{
services.kubernetes.roles = [ "master" ];
}
While this will enable the kubelet and kube-proxy only:
{
services.kubernetes.roles = [ "node" ];
}
Assigning both the master and node roles is usable if you want a single node Kubernetes cluster for dev or testing purposes:
{
services.kubernetes.roles = [ "master" "node" ];
}
Note: Assigning either role will also default both
services.kubernetes.flannel.enable
and services.kubernetes.easyCerts
to true. This sets up flannel as CNI and activates automatic PKI bootstrapping.
As of NixOS 19.03, it is mandatory to configure:
services.kubernetes.masterAddress
.
The masterAddress must be resolveable and routeable by all cluster nodes.
In single node clusters, this can be set to localhost
.
Role-based access control (RBAC) authorization mode is enabled by default. This means that anonymous requests to the apiserver secure port will expectedly cause a permission denied error. All cluster components must therefore be configured with x509 certificates for two-way tls communication. The x509 certificate subject section determines the roles and permissions granted by the apiserver to perform clusterwide or namespaced operations. See also: Using RBAC Authorization.
The NixOS kubernetes module provides an option for automatic certificate
bootstrapping and configuration,
services.kubernetes.easyCerts
.
The PKI bootstrapping process involves setting up a certificate authority (CA)
daemon (cfssl) on the kubernetes master node. cfssl generates a CA-cert
for the cluster, and uses the CA-cert for signing subordinate certs issued
to each of the cluster components. Subsequently, the certmgr daemon monitors
active certificates and renews them when needed. For single node Kubernetes
clusters, setting services.kubernetes.easyCerts
= true is sufficient and no further action is required. For joining extra node
machines to an existing cluster on the other hand, establishing initial
trust is mandatory.
To add new nodes to the cluster: On any (non-master) cluster node where
services.kubernetes.easyCerts
is enabled, the helper script nixos-kubernetes-node-join
is available on PATH.
Given a token on stdin, it will copy the token to the kubernetes secrets directory
and restart the certmgr service. As requested certificates are issued, the
script will restart kubernetes cluster components as needed for them to
pick up new keypairs.
Multi-master (HA) clusters are not supported by the easyCerts module.
In order to interact with an RBAC-enabled cluster as an administrator,
one needs to have cluster-admin privileges. By default, when easyCerts
is enabled, a cluster-admin kubeconfig file is generated and linked into
/etc/kubernetes/cluster-admin.kubeconfig
as determined by
services.kubernetes.pki.etcClusterAdminKubeconfig
.
export KUBECONFIG=/etc/kubernetes/cluster-admin.kubeconfig
will make
kubectl use this kubeconfig to access and authenticate the cluster. The
cluster-admin kubeconfig references an auto-generated keypair owned by
root. Thus, only root on the kubernetes master may obtain cluster-admin
rights by means of this file.
This chapter describes various aspects of managing a running NixOS system, such as how to use the systemd service manager.
Table of Contents
In NixOS, all system services are started and monitored using the
systemd program. systemd is the “init” process of the system (i.e. PID
1), the parent of all other processes. It manages a set of so-called
“units”, which can be things like system services (programs), but also
mount points, swap files, devices, targets (groups of units) and more.
Units can have complex dependencies; for instance, one unit can require
that another unit must be successfully started before the first unit can
be started. When the system boots, it starts a unit named
default.target
; the dependencies of this unit cause all system
services to be started, file systems to be mounted, swap files to be
activated, and so on.
The command systemctl
is the main way to interact with systemd
. The
following paragraphs demonstrate ways to interact with any OS running
systemd as init system. NixOS is of no exception. The next section
explains NixOS specific things worth
knowing.
Without any arguments, systemctl
the status of active units:
$ systemctl
-.mount loaded active mounted /
swapfile.swap loaded active active /swapfile
sshd.service loaded active running SSH Daemon
graphical.target loaded active active Graphical Interface
...
You can ask for detailed status information about a unit, for instance, the PostgreSQL database service:
$ systemctl status postgresql.service
postgresql.service - PostgreSQL Server
Loaded: loaded (/nix/store/pn3q73mvh75gsrl8w7fdlfk3fq5qm5mw-unit/postgresql.service)
Active: active (running) since Mon, 2013-01-07 15:55:57 CET; 9h ago
Main PID: 2390 (postgres)
CGroup: name=systemd:/system/postgresql.service
├─2390 postgres
├─2418 postgres: writer process
├─2419 postgres: wal writer process
├─2420 postgres: autovacuum launcher process
├─2421 postgres: stats collector process
└─2498 postgres: zabbix zabbix [local] idle
Jan 07 15:55:55 hagbard postgres[2394]: [1-1] LOG: database system was shut down at 2013-01-07 15:55:05 CET
Jan 07 15:55:57 hagbard postgres[2390]: [1-1] LOG: database system is ready to accept connections
Jan 07 15:55:57 hagbard postgres[2420]: [1-1] LOG: autovacuum launcher started
Jan 07 15:55:57 hagbard systemd[1]: Started PostgreSQL Server.
Note that this shows the status of the unit (active and running), all the processes belonging to the service, as well as the most recent log messages from the service.
Units can be stopped, started or restarted:
# systemctl stop postgresql.service
# systemctl start postgresql.service
# systemctl restart postgresql.service
These operations are synchronous: they wait until the service has finished starting or stopping (or has failed). Starting a unit will cause the dependencies of that unit to be started as well (if necessary).
Packages in Nixpkgs sometimes provide systemd units with them, usually
in e.g #pkg-out#/lib/systemd/
. Putting such a package in
environment.systemPackages
doesn’t make the service available to
users or the system.
In order to enable a systemd system service with provided upstream package, use (e.g):
{
systemd.packages = [ pkgs.packagekit ];
}
Usually NixOS modules written by the community do the above, plus take
care of other details. If a module was written for a service you are
interested in, you’d probably need only to use
services.#name#.enable = true;
. These services are defined in
Nixpkgs’ nixos/modules/
directory
. In case
the service is simple enough, the above method should work, and start
the service on boot.
User systemd services on the other hand, should be treated
differently. Given a package that has a systemd unit file at
#pkg-out#/lib/systemd/user/
, using systemd.packages
will
make you able to start the service via systemctl --user start
, but it
won’t start automatically on login. However, You can imperatively
enable it by adding the package’s attribute to
systemd.packages
and then do this (e.g):
$ mkdir -p ~/.config/systemd/user/default.target.wants
$ ln -s /run/current-system/sw/lib/systemd/user/syncthing.service ~/.config/systemd/user/default.target.wants/
$ systemctl --user daemon-reload
$ systemctl --user enable syncthing.service
If you are interested in a timer file, use timers.target.wants
instead
of default.target.wants
in the 1st and 2nd command.
Using systemctl --user enable syncthing.service
instead of the above,
will work, but it’ll use the absolute path of syncthing.service
for
the symlink, and this path is in /nix/store/.../lib/systemd/user/
.
Hence garbage collection will remove that file and you
will wind up with a broken symlink in your systemd configuration, which
in turn will not make the service / timer start on login.
systemd supports templated units where a base unit can be started multiple
times with a different parameter. The syntax to accomplish this is
service-name@instance-name.service
. Units get the instance name passed to
them (see systemd.unit(5)
). NixOS has support for these kinds of units and
for template-specific overrides. A service needs to be defined twice, once
for the base unit and once for the instance. All instances must include
overrideStrategy = "asDropin"
for the change detection to work. This
example illustrates this:
{
systemd.services = {
"base-unit@".serviceConfig = {
ExecStart = "...";
User = "...";
};
"base-unit@instance-a" = {
overrideStrategy = "asDropin"; # needed for templates to work
wantedBy = [ "multi-user.target" ]; # causes NixOS to manage the instance
};
"base-unit@instance-b" = {
overrideStrategy = "asDropin"; # needed for templates to work
wantedBy = [ "multi-user.target" ]; # causes NixOS to manage the instance
serviceConfig.User = "root"; # also override something for this specific instance
};
};
}
The system can be shut down (and automatically powered off) by doing:
# shutdown
This is equivalent to running systemctl poweroff
.
To reboot the system, run
# reboot
which is equivalent to systemctl reboot
. Alternatively, you can
quickly reboot the system using kexec
, which bypasses the BIOS by
directly loading the new kernel into memory:
# systemctl kexec
The machine can be suspended to RAM (if supported) using systemctl suspend
,
and suspended to disk using systemctl hibernate
.
These commands can be run by any user who is logged in locally, i.e. on a virtual console or in X11; otherwise, the user is asked for authentication.
Systemd keeps track of all users who are logged into the system (e.g. on
a virtual console or remotely via SSH). The command loginctl
allows
querying and manipulating user sessions. For instance, to list all user
sessions:
$ loginctl
SESSION UID USER SEAT
c1 500 eelco seat0
c3 0 root seat0
c4 500 alice
This shows that two users are logged in locally, while another is logged in remotely. (“Seats” are essentially the combinations of displays and input devices attached to the system; usually, there is only one seat.) To get information about a session:
$ loginctl session-status c3
c3 - root (0)
Since: Tue, 2013-01-08 01:17:56 CET; 4min 42s ago
Leader: 2536 (login)
Seat: seat0; vc3
TTY: /dev/tty3
Service: login; type tty; class user
State: online
CGroup: name=systemd:/user/root/c3
├─ 2536 /nix/store/10mn4xip9n7y9bxqwnsx7xwx2v2g34xn-shadow-4.1.5.1/bin/login --
├─10339 -bash
└─10355 w3m nixos.org
This shows that the user is logged in on virtual console 3. It also lists the processes belonging to this session. Since systemd keeps track of this, you can terminate a session in a way that ensures that all the session’s processes are gone:
# loginctl terminate-session c3
To keep track of the processes in a running system, systemd uses control groups (cgroups). A control group is a set of processes used to allocate resources such as CPU, memory or I/O bandwidth. There can be multiple control group hierarchies, allowing each kind of resource to be managed independently.
The command systemd-cgls
lists all control groups in the systemd
hierarchy, which is what systemd uses to keep track of the processes
belonging to each service or user session:
$ systemd-cgls
├─user
│ └─eelco
│ └─c1
│ ├─ 2567 -:0
│ ├─ 2682 kdeinit4: kdeinit4 Running...
│ ├─ ...
│ └─10851 sh -c less -R
└─system
├─httpd.service
│ ├─2444 httpd -f /nix/store/3pyacby5cpr55a03qwbnndizpciwq161-httpd.conf -DNO_DETACH
│ └─...
├─dhcpcd.service
│ └─2376 dhcpcd --config /nix/store/f8dif8dsi2yaa70n03xir8r653776ka6-dhcpcd.conf
└─ ...
Similarly, systemd-cgls cpu
shows the cgroups in the CPU hierarchy,
which allows per-cgroup CPU scheduling priorities. By default, every
systemd service gets its own CPU cgroup, while all user sessions are in
the top-level CPU cgroup. This ensures, for instance, that a thousand
run-away processes in the httpd.service
cgroup cannot starve the CPU
for one process in the postgresql.service
cgroup. (By contrast, it
they were in the same cgroup, then the PostgreSQL process would get
1/1001 of the cgroup’s CPU time.) You can limit a service’s CPU share in
configuration.nix
:
{
systemd.services.httpd.serviceConfig.CPUShares = 512;
}
By default, every cgroup has 1024 CPU shares, so this will halve the CPU
allocation of the httpd.service
cgroup.
There also is a memory
hierarchy that controls memory allocation
limits; by default, all processes are in the top-level cgroup, so any
service or session can exhaust all available memory. Per-cgroup memory
limits can be specified in configuration.nix
; for instance, to limit
httpd.service
to 512 MiB of RAM (excluding swap):
{
systemd.services.httpd.serviceConfig.MemoryLimit = "512M";
}
The command systemd-cgtop
shows a continuously updated list of all
cgroups with their CPU and memory usage.
System-wide logging is provided by systemd’s journal, which subsumes
traditional logging daemons such as syslogd and klogd. Log entries are
kept in binary files in /var/log/journal/
. The command journalctl
allows you to see the contents of the journal. For example,
$ journalctl -b
shows all journal entries since the last reboot. (The output of
journalctl
is piped into less
by default.) You can use various
options and match operators to restrict output to messages of interest.
For instance, to get all messages from PostgreSQL:
$ journalctl -u postgresql.service
-- Logs begin at Mon, 2013-01-07 13:28:01 CET, end at Tue, 2013-01-08 01:09:57 CET. --
...
Jan 07 15:44:14 hagbard postgres[2681]: [2-1] LOG: database system is shut down
-- Reboot --
Jan 07 15:45:10 hagbard postgres[2532]: [1-1] LOG: database system was shut down at 2013-01-07 15:44:14 CET
Jan 07 15:45:13 hagbard postgres[2500]: [1-1] LOG: database system is ready to accept connections
Or to get all messages since the last reboot that have at least a “critical” severity level:
$ journalctl -b -p crit
Dec 17 21:08:06 mandark sudo[3673]: pam_unix(sudo:auth): auth could not identify password for [alice]
Dec 29 01:30:22 mandark kernel[6131]: [1053513.909444] CPU6: Core temperature above threshold, cpu clock throttled (total events = 1)
The system journal is readable by root and by users in the wheel
and
systemd-journal
groups. All users have a private journal that can be
read using journalctl
.
Normally — on systems with a persistent rootfs
— system services can persist state to
the filesystem without administrator intervention.
However, it is possible and not-uncommon to create impermanent systems, whose
rootfs
is either a tmpfs
or reset during boot. While NixOS itself supports
this kind of configuration, special care needs to be taken.
/nix
NixOS needs the entirety of /nix
to be persistent, as it includes:
/nix/store
, which contains all the system’s executables, libraries, and supporting data;
/nix/var/nix
, which contains:
the Nix daemon’s database;
roots whose transitive closure is preserved when garbage-collecting the Nix store;
system-wide and per-user profiles.
/boot
/boot
should also be persistent, as it contains:
the kernel and initrd which the bootloader loads,
the bootloader’s configuration, including the kernel’s command-line which determines the store path to use as system environment.
machine-id(5)
systemd
uses per-machine identifier — machine-id(5) — which must be
unique and persistent; otherwise, the system journal may fail to list earlier
boots, etc.
systemd
generates a random machine-id(5)
during boot if it does not already exist,
and persists it in /etc/machine-id
. As such, it suffices to make that file persistent.
Alternatively, it is possible to generate a random machine-id(5)
; while the
specification allows for any hex-encoded 128b value, systemd itself uses
UUIDv4, i.e. random UUIDs, and it is thus preferable to do so as well, in
case some software assumes machine-id(5)
to be a UUIDv4. Those can be
generated with uuidgen -r | tr -d -
(tr
being used to remove the dashes).
Such a machine-id(5)
can be set by writing it to /etc/machine-id
or through
the kernel’s command-line, though NixOS’ systemd maintainers discourage the
latter approach.
/var/lib/systemd
Moreover, systemd
expects its state directory — /var/lib/systemd
— to persist, for:
systemd-random-seed(8), which loads a 256b “seed” into the kernel’s RNG at boot time, and saves a fresh one during shutdown;
systemd.timer(5) with Persistent=yes
, which are then run after boot if
the timer would have triggered during the time the system was shut down;
systemd-coredump(8) to store core dumps there by default; (see coredump.conf(5))
systemd-backlight(8) and systemd-rfkill(8) persist hardware-related state;
possibly other things, this list is not meant to be exhaustive.
In any case, making /var/lib/systemd
persistent is recommended.
/var/log/journal/{machine-id}
Lastly, systemd-journald(8) writes the system’s journal in binary
form to /var/log/journal/{machine-id}
; if (locally) persisting the entire log
is desired, it is recommended to make all of /var/log/journal
persistent.
If not, one can set Storage=volatile
in journald.conf(5)
(services.journald.storage = "volatile";
),
which disables journal persistence and causes it to be written to
/run/log/journal
.
When using ZFS, /etc/zfs/zpool.cache
should be persistent (or a symlink to a persistent
location) as it is the default value for the cachefile
property.
This cachefile is used on system startup to discover ZFS pools, so ZFS pools
holding the rootfs
and/or early-boot datasets such as /nix
can be set to
cachefile=none
.
In principle, if there are no other pools attached to the system, zpool.cache
does not need to be persisted; it is however strongly recommended to persist
it, in case additional pools are added later on, temporarily or permanently:
While mishandling the cachefile does not lead to data loss by itself, it may cause zpools not to be imported during boot, and services may then write to a location where a dataset was expected to be mounted.
Table of Contents
Nix has a purely functional model, meaning that packages are never
upgraded in place. Instead new versions of packages end up in a
different location in the Nix store (/nix/store
). You should
periodically run Nix’s garbage collector to remove old, unreferenced
packages. This is easy:
$ nix-collect-garbage
Alternatively, you can use a systemd unit that does the same in the background:
# systemctl start nix-gc.service
You can tell NixOS in configuration.nix
to run this unit automatically
at certain points in time, for instance, every night at 03:15:
{
nix.gc.automatic = true;
nix.gc.dates = "03:15";
}
The commands above do not remove garbage collector roots, such as old system configurations. Thus they do not remove the ability to roll back to previous configurations. The following command deletes old roots, removing the ability to roll back to them:
$ nix-collect-garbage -d
You can also do this for specific profiles, e.g.
$ nix-env -p /nix/var/nix/profiles/per-user/eelco/profile --delete-generations old
Note that NixOS system configurations are stored in the profile
/nix/var/nix/profiles/system
.
Another way to reclaim disk space (often as much as 40% of the size of the Nix store) is to run Nix’s store optimiser, which seeks out identical files in the store and replaces them with hard links to a single copy.
$ nix-store --optimise
Since this command needs to read the entire Nix store, it can take quite a while to finish.
If your /boot
partition runs out of space, after clearing old profiles
you must rebuild your system with nixos-rebuild boot
or nixos-rebuild switch
to update the /boot
partition and clear space.
Table of Contents
NixOS allows you to easily run other NixOS instances as containers. Containers are a light-weight approach to virtualisation that runs software in the container at the same speed as in the host system. NixOS containers share the Nix store of the host, making container creation very efficient.
Currently, NixOS containers are not perfectly isolated from the host system. This means that a user with root access to the container can do things that affect the host. So you should not give container root access to untrusted users.
NixOS containers can be created in two ways: imperatively, using the
command nixos-container
, and declaratively, by specifying them in your
configuration.nix
. The declarative approach implies that containers
get upgraded along with your host system when you run nixos-rebuild
,
which is often not what you want. By contrast, in the imperative
approach, containers are configured and updated independently from the
host system.
We’ll cover imperative container management using nixos-container
first. Be aware that container management is currently only possible as
root
.
You create a container with identifier foo
as follows:
# nixos-container create foo
This creates the container’s root directory in /var/lib/nixos-containers/foo
and a small configuration file in /etc/nixos-containers/foo.conf
. It also
builds the container’s initial system configuration and stores it in
/nix/var/nix/profiles/per-container/foo/system
. You can modify the
initial configuration of the container on the command line. For
instance, to create a container that has sshd
running, with the given
public key for root
:
# nixos-container create foo --config '
services.openssh.enable = true;
users.users.root.openssh.authorizedKeys.keys = ["ssh-dss AAAAB3N…"];
'
By default the next free address in the 10.233.0.0/16
subnet will be
chosen as container IP. This behavior can be altered by setting
--host-address
and --local-address
:
# nixos-container create test --config-file test-container.nix \
--local-address 10.235.1.2 --host-address 10.235.1.1
Creating a container does not start it. To start the container, run:
# nixos-container start foo
This command will return as soon as the container has booted and has
reached multi-user.target
. On the host, the container runs within a
systemd unit called container@container-name.service
. Thus, if
something went wrong, you can get status info using systemctl
:
# systemctl status container@foo
If the container has started successfully, you can log in as root using
the root-login
operation:
# nixos-container root-login foo
[root@foo:~]#
Note that only root on the host can do this (since there is no
authentication). You can also get a regular login prompt using the
login
operation, which is available to all users on the host:
# nixos-container login foo
foo login: alice
Password: ***
With nixos-container run
, you can execute arbitrary commands in the
container:
# nixos-container run foo -- uname -a
Linux foo 3.4.82 #1-NixOS SMP Thu Mar 20 14:44:05 UTC 2014 x86_64 GNU/Linux
There are several ways to change the configuration of the container.
First, on the host, you can edit
/var/lib/nixos-containers/foo/etc/nixos/configuration.nix
, and run
# nixos-container update foo
This will build and activate the new configuration. You can also specify a new configuration on the command line:
# nixos-container update foo --config '
services.httpd.enable = true;
services.httpd.adminAddr = "foo@example.org";
networking.firewall.allowedTCPPorts = [ 80 ];
'
# curl http://$(nixos-container show-ip foo)/
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN">…
However, note that this will overwrite the container’s
/etc/nixos/configuration.nix
.
Alternatively, you can change the configuration from within the
container itself by running nixos-rebuild switch
inside the container.
Note that the container by default does not have a copy of the NixOS
channel, so you should run nix-channel --update
first.
Containers can be stopped and started using nixos-container stop
and nixos-container start
, respectively, or by using
systemctl
on the container’s service unit. To destroy a container,
including its file system, do
# nixos-container destroy foo
You can also specify containers and their configuration in the host’s
configuration.nix
. For example, the following specifies that there
shall be a container named database
running PostgreSQL:
{
containers.database =
{ config =
{ config, pkgs, ... }:
{ services.postgresql.enable = true;
services.postgresql.package = pkgs.postgresql_14;
};
};
}
If you run nixos-rebuild switch
, the container will be built. If the
container was already running, it will be updated in place, without
rebooting. The container can be configured to start automatically by
setting containers.database.autoStart = true
in its configuration.
By default, declarative containers share the network namespace of the host, meaning that they can listen on (privileged) ports. However, they cannot change the network configuration. You can give a container its own network as follows:
{
containers.database = {
privateNetwork = true;
hostAddress = "192.168.100.10";
localAddress = "192.168.100.11";
};
}
This gives the container a private virtual Ethernet interface with IP
address 192.168.100.11
, which is hooked up to a virtual Ethernet
interface on the host with IP address 192.168.100.10
. (See the next
section for details on container networking.)
To disable the container, just remove it from configuration.nix
and
run nixos-rebuild switch
. Note that this will not delete the root directory of the
container in /var/lib/nixos-containers
. Containers can be destroyed using
the imperative method: nixos-container destroy foo
.
Declarative containers can be started and stopped using the
corresponding systemd service, e.g.
systemctl start container@database
.
When you create a container using nixos-container create
, it gets it
own private IPv4 address in the range 10.233.0.0/16
. You can get the
container’s IPv4 address as follows:
# nixos-container show-ip foo
10.233.4.2
$ ping -c1 10.233.4.2
64 bytes from 10.233.4.2: icmp_seq=1 ttl=64 time=0.106 ms
Networking is implemented using a pair of virtual Ethernet devices. The
network interface in the container is called eth0
, while the matching
interface in the host is called ve-container-name
(e.g., ve-foo
).
The container has its own network namespace and the CAP_NET_ADMIN
capability, so it can perform arbitrary network configuration such as
setting up firewall rules, without affecting or having access to the
host’s network.
By default, containers cannot talk to the outside network. If you want that, you should set up Network Address Translation (NAT) rules on the host to rewrite container traffic to use your external IP address. This can be accomplished using the following configuration on the host:
{
networking.nat.enable = true;
networking.nat.internalInterfaces = ["ve-+"];
networking.nat.externalInterface = "eth0";
}
where eth0
should be replaced with the desired external interface.
Note that ve-+
is a wildcard that matches all container interfaces.
If you are using Network Manager, you need to explicitly prevent it from managing container interfaces:
{
networking.networkmanager.unmanaged = [ "interface-name:ve-*" ];
}
You may need to restart your system for the changes to take effect.
Table of Contents
This chapter describes solutions to common problems you might encounter when you manage your NixOS system.
If NixOS fails to boot, there are a number of kernel command line parameters that may help you to identify or fix the issue. You can add these parameters in the GRUB boot menu by pressing “e” to modify the selected boot entry and editing the line starting with linux
. The following are some useful kernel command line parameters that are recognised by the NixOS boot scripts or by systemd:
boot.shell_on_fail
Allows the user to start a root shell if something goes wrong in stage 1 of the boot process (the initial ramdisk). This is disabled by default because there is no authentication for the root shell.
boot.debug1
Start an interactive shell in stage 1 before anything useful has been done. That is, no modules have been loaded and no file systems have been mounted, except for /proc
and /sys
.
boot.debug1devices
Like boot.debug1
, but runs stage1 until kernel modules are loaded and device nodes are created. This may help with e.g. making the keyboard work.
boot.debug1mounts
Like boot.debug1
or boot.debug1devices
, but runs stage1 until all filesystems that are mounted during initrd are mounted (see neededForBoot). As a motivating example, this could be useful if you’ve forgotten to set neededForBoot on a file system.
boot.trace
Print every shell command executed by the stage 1 and 2 boot scripts.
single
Boot into rescue mode (a.k.a. single user mode). This will cause systemd to start nothing but the unit rescue.target
, which runs sulogin
to prompt for the root password and start a root login shell. Exiting the shell causes the system to continue with the normal boot process.
systemd.log_level=debug
systemd.log_target=console
Make systemd very verbose and send log messages to the console instead of the journal. For more parameters recognised by systemd, see systemd(1).
In addition, these arguments are recognised by the live image only:
live.nixos.passwd=password
Set the password for the nixos
live user. This can be used for SSH access if there are issues using the terminal.
Notice that for boot.shell_on_fail
, boot.debug1
, boot.debug1devices
, and boot.debug1mounts
, if you did not select “start the new shell as pid 1”, and you exit
from the new shell, boot will proceed normally from the point where it failed, as if you’d chosen “ignore the error and continue”.
If no login prompts or X11 login screens appear (e.g. due to hanging dependencies), you can press Alt+ArrowUp. If you’re lucky, this will start rescue mode (described above). (Also note that since most units have a 90-second timeout before systemd gives up on them, the agetty
login prompts should appear eventually unless something is very wrong.)
You can enter rescue mode by running:
# systemctl rescue
This will eventually give you a single-user root shell. Systemd will stop (almost) all system services. To get out of maintenance mode, just exit from the rescue shell.
After running nixos-rebuild
to switch to a new configuration, you may
find that the new configuration doesn’t work very well. In that case,
there are several ways to return to a previous configuration.
First, the GRUB boot manager allows you to boot into any previous configuration that hasn’t been garbage-collected. These configurations can be found under the GRUB submenu “NixOS - All configurations”. This is especially useful if the new configuration fails to boot. After the system has booted, you can make the selected configuration the default for subsequent boots:
# /run/current-system/bin/switch-to-configuration boot
Second, you can switch to the previous configuration in a running system:
# nixos-rebuild switch --rollback
This is equivalent to running:
# /nix/var/nix/profiles/system-N-link/bin/switch-to-configuration switch
where N
is the number of the NixOS system configuration. To get a
list of the available configurations, do:
$ ls -l /nix/var/nix/profiles/system-*-link
...
lrwxrwxrwx 1 root root 78 Aug 12 13:54 /nix/var/nix/profiles/system-268-link -> /nix/store/202b...-nixos-13.07pre4932_5a676e4-4be1055
After a system crash, it’s possible for files in the Nix store to become
corrupted. (For instance, the Ext4 file system has the tendency to
replace un-synced files with zero bytes.) NixOS tries hard to prevent
this from happening: it performs a sync
before switching to a new
configuration, and Nix’s database is fully transactional. If corruption
still occurs, you may be able to fix it automatically.
If the corruption is in a path in the closure of the NixOS system configuration, you can fix it by doing
# nixos-rebuild switch --repair
This will cause Nix to check every path in the closure, and if its cryptographic hash differs from the hash recorded in Nix’s database, the path is rebuilt or redownloaded.
You can also scan the entire Nix store for corrupt paths:
# nix-store --verify --check-contents --repair
Any corrupt paths will be redownloaded if they’re available in a binary cache; otherwise, they cannot be repaired.
Nix uses a so-called binary cache to optimise building a package from
source into downloading it as a pre-built binary. That is, whenever a
command like nixos-rebuild
needs a path in the Nix store, Nix will try
to download that path from the Internet rather than build it from
source. The default binary cache is https://cache.nixos.org/
. If this
cache is unreachable, Nix operations may take a long time due to HTTP
connection timeouts. You can disable the use of the binary cache by
adding --option use-binary-caches false
, e.g.
# nixos-rebuild switch --option use-binary-caches false
If you have an alternative binary cache at your disposal, you can use it instead:
# nixos-rebuild switch --option binary-caches http://my-cache.example.org/
This chapter describes how you can modify and extend NixOS.
By default, NixOS’s nixos-rebuild
command uses the NixOS and Nixpkgs
sources provided by the nixos
channel (kept in
/nix/var/nix/profiles/per-user/root/channels/nixos
). To modify NixOS,
however, you should check out the latest sources from Git. This is as
follows:
$ git clone https://github.com/NixOS/nixpkgs
$ cd nixpkgs
$ git remote update origin
This will check out the latest Nixpkgs sources to ./nixpkgs
the NixOS
sources to ./nixpkgs/nixos
. (The NixOS source tree lives in a
subdirectory of the Nixpkgs repository.) The nixpkgs
repository has
branches that correspond to each Nixpkgs/NixOS channel (see
Upgrading NixOS for more information about channels). Thus, the
Git branch origin/nixos-17.03
will contain the latest built and tested
version available in the nixos-17.03
channel.
It’s often inconvenient to develop directly on the master branch, since if somebody has just committed (say) a change to GCC, then the binary cache may not have caught up yet and you’ll have to rebuild everything from source. So you may want to create a local branch based on your current NixOS version:
$ nixos-version
17.09pre104379.6e0b727 (Hummingbird)
$ git checkout -b local 6e0b727
Or, to base your local branch on the latest version available in a NixOS channel:
$ git remote update origin
$ git checkout -b local origin/nixos-17.03
(Replace nixos-17.03
with the name of the channel you want to use.)
You can use git merge
or git rebase
to keep your local branch in sync with the channel, e.g.
$ git remote update origin
$ git merge origin/nixos-17.03
You can use git cherry-pick
to copy commits from your local branch to
the upstream branch.
If you want to rebuild your system using your (modified) sources, you
need to tell nixos-rebuild
about them using the -I
flag:
# nixos-rebuild switch -I nixpkgs=/my/sources/nixpkgs
If you want nix-env
to use the expressions in /my/sources
, use
nix-env -f /my/sources/nixpkgs
, or change the default by adding a symlink in
~/.nix-defexpr
:
$ ln -s /my/sources/nixpkgs ~/.nix-defexpr/nixpkgs
You may want to delete the symlink ~/.nix-defexpr/channels_root
to
prevent root’s NixOS channel from clashing with your own tree (this may
break the command-not-found utility though). If you want to go back to
the default state, you may just remove the ~/.nix-defexpr
directory
completely, log out and log in again and it should have been recreated
with a link to the root channels.
Table of Contents
NixOS has a modular system for declarative configuration. This system
combines multiple modules to produce the full system configuration.
One of the modules that constitute the configuration is
/etc/nixos/configuration.nix
. Most of the others live in the
nixos/modules
subdirectory of the Nixpkgs tree.
Each NixOS module is a file that handles one logical aspect of the
configuration, such as a specific kind of hardware, a service, or
network settings. A module configuration does not have to handle
everything from scratch; it can use the functionality provided by other
modules for its implementation. Thus a module can declare options that
can be used by other modules, and conversely can define options
provided by other modules in its own implementation. For example, the
module
pam.nix
declares the option security.pam.services
that allows other modules (e.g.
sshd.nix
)
to define PAM services; and it defines the option environment.etc
(declared by
etc.nix
)
to cause files to be created in /etc/pam.d
.
In Configuration Syntax, we saw the following structure of NixOS modules:
{ config, pkgs, ... }:
{ # option definitions
}
This is actually an abbreviated form of module that only defines options, but does not declare any. The structure of full NixOS modules is shown in Example: Structure of NixOS Modules.
{ config, pkgs, ... }:
{
imports =
[ # paths of other modules
];
options = {
# option declarations
};
config = {
# option definitions
};
}
The meaning of each part is as follows.
The first line makes the current Nix expression a function. The variable
pkgs
contains Nixpkgs (by default, it takes the nixpkgs
entry of
NIX_PATH
, see the Nix manual
for further details), while config
contains the full system
configuration. This line can be omitted if there is no reference to
pkgs
and config
inside the module.
This imports
list enumerates the paths to other NixOS modules that
should be included in the evaluation of the system configuration. A
default set of modules is defined in the file modules/module-list.nix
.
These don’t need to be added in the import list.
The attribute options
is a nested set of option declarations
(described below).
The attribute config
is a nested set of option definitions (also
described below).
Example: NixOS Module for the “locate” Service
shows a module that handles the regular update of the “locate” database,
an index of all files in the file system. This module declares two
options that can be defined by other modules (typically the user’s
configuration.nix
): services.locate.enable
(whether the database should
be updated) and services.locate.interval
(when the update should be done).
It implements its functionality by defining two options declared by other
modules: systemd.services
(the set of all systemd services) and
systemd.timers
(the list of commands to be executed periodically by
systemd
).
Care must be taken when writing systemd services using Exec*
directives. By
default systemd performs substitution on %<char>
specifiers in these
directives, expands environment variables from $FOO
and ${FOO}
, splits
arguments on whitespace, and splits commands on ;
. All of these must be escaped
to avoid unexpected substitution or splitting when interpolating into an Exec*
directive, e.g. when using an extraArgs
option to pass additional arguments to
the service. The functions utils.escapeSystemdExecArg
and
utils.escapeSystemdExecArgs
are provided for this, see Example: Escaping in
Exec directives for an example. When using these
functions system environment substitution should not be disabled explicitly.
{ config, lib, pkgs, ... }:
let
inherit (lib) concatStringsSep mkIf mkOption optionalString types;
cfg = config.services.locate;
in {
options.services.locate = {
enable = mkOption {
type = types.bool;
default = false;
description = ''
If enabled, NixOS will periodically update the database of
files used by the locate command.
'';
};
interval = mkOption {
type = types.str;
default = "02:15";
example = "hourly";
description = ''
Update the locate database at this interval. Updates by
default at 2:15 AM every day.
The format is described in
systemd.time(7).
'';
};
# Other options omitted for documentation
};
config = {
systemd.services.update-locatedb =
{ description = "Update Locate Database";
path = [ pkgs.su ];
script =
''
mkdir -m 0755 -p $(dirname ${toString cfg.output})
exec updatedb \
--localuser=${cfg.localuser} \
${optionalString (!cfg.includeStore) "--prunepaths='/nix/store'"} \
--output=${toString cfg.output} ${concatStringsSep " " cfg.extraFlags}
'';
};
systemd.timers.update-locatedb = mkIf cfg.enable
{ description = "Update timer for locate database";
partOf = [ "update-locatedb.service" ];
wantedBy = [ "timers.target" ];
timerConfig.OnCalendar = cfg.interval;
};
};
}
{ config, pkgs, utils, ... }:
let
cfg = config.services.echo;
echoAll = pkgs.writeScript "echo-all" ''
#! ${pkgs.runtimeShell}
for s in "$@"; do
printf '%s\n' "$s"
done
'';
args = [ "a%Nything" "lang=\${LANG}" ";" "/bin/sh -c date" ];
in {
systemd.services.echo =
{ description = "Echo to the journal";
wantedBy = [ "multi-user.target" ];
serviceConfig.Type = "oneshot";
serviceConfig.ExecStart = ''
${echoAll} ${utils.escapeSystemdExecArgs args}
'';
};
}
An option declaration specifies the name, type and description of a NixOS configuration option. It is invalid to define an option that hasn’t been declared in any module. An option declaration generally looks like this:
{
options = {
name = mkOption {
type = type specification;
default = default value;
example = example value;
description = "Description for use in the NixOS manual.";
};
};
}
The attribute names within the name
attribute path must be camel
cased in general but should, as an exception, match the package
attribute name
when referencing a Nixpkgs package. For example, the option
services.nix-serve.bindAddress
references the nix-serve
Nixpkgs
package.
The function mkOption
accepts the following arguments.
type
The type of the option (see the section called “Options Types”). This argument is mandatory for nixpkgs modules. Setting this is highly recommended for the sake of documentation and type checking. In case it is not set, a fallback type with unspecified behavior is used.
default
The default value used if no value is defined by any module. A default is not required; but if a default is not given, then users of the module will have to define the value of the option, otherwise an error will be thrown.
defaultText
A textual representation of the default value to be rendered verbatim in
the manual. Useful if the default value is a complex expression or depends
on other values or packages.
Use lib.literalExpression
for a Nix expression, lib.literalMD
for
a plain English description in Nixpkgs-flavored Markdown format.
example
An example value that will be shown in the NixOS manual.
You can use lib.literalExpression
and lib.literalMD
in the same way
as in defaultText
.
description
A textual description of the option in Nixpkgs-flavored Markdown format that will be included in the NixOS manual.
mkEnableOption
Creates an Option attribute set for a boolean value option i.e an option to be toggled on or off.
This function takes a single string argument, the name of the thing to be toggled.
The option’s description is “Whether to enable <name>.”.
For example:
mkEnableOption
usagelib.mkEnableOption "magic"
# is like
lib.mkOption {
type = lib.types.bool;
default = false;
example = true;
description = "Whether to enable magic.";
}
mkPackageOption
Usage:
mkPackageOption pkgs "name" { default = [ "path" "in" "pkgs" ]; example = "literal example"; }
Creates an Option attribute set for an option that specifies the package a module should use for some purpose.
Note: You shouldn’t necessarily make package options for all of your modules. You can always overwrite a specific package throughout nixpkgs by using nixpkgs overlays.
The package is specified in the third argument under default
as a list of strings
representing its attribute path in nixpkgs (or another package set).
Because of this, you need to pass nixpkgs itself (or a subset) as the first argument.
The second argument may be either a string or a list of strings.
It provides the display name of the package in the description of the generated option
(using only the last element if the passed value is a list)
and serves as the fallback value for the default
argument.
To include extra information in the description, pass extraDescription
to
append arbitrary text to the generated description.
You can also pass an example
value, either a literal string or an attribute path.
The default argument can be omitted if the provided name is an attribute of pkgs (if name is a string) or a valid attribute path in pkgs (if name is a list).
If you wish to explicitly provide no default, pass null
as default
.
Examples:
mkPackageOption
usagelib.mkPackageOption pkgs "hello" { }
# is like
lib.mkOption {
type = lib.types.package;
default = pkgs.hello;
defaultText = lib.literalExpression "pkgs.hello";
description = "The hello package to use.";
}
mkPackageOption
with explicit default and examplelib.mkPackageOption pkgs "GHC" {
default = [ "ghc" ];
example = "pkgs.haskell.packages.ghc92.ghc.withPackages (hkgs: [ hkgs.primes ])";
}
# is like
lib.mkOption {
type = lib.types.package;
default = pkgs.ghc;
defaultText = lib.literalExpression "pkgs.ghc";
example = lib.literalExpression "pkgs.haskell.packages.ghc92.ghc.withPackages (hkgs: [ hkgs.primes ])";
description = "The GHC package to use.";
}
mkPackageOption
with additional description textmkPackageOption pkgs [ "python39Packages" "pytorch" ] {
extraDescription = "This is an example and doesn't actually do anything.";
}
# is like
lib.mkOption {
type = lib.types.package;
default = pkgs.python39Packages.pytorch;
defaultText = lib.literalExpression "pkgs.python39Packages.pytorch";
description = "The pytorch package to use. This is an example and doesn't actually do anything.";
}
Extensible option types is a feature that allows to extend certain types
declaration through multiple module files. This feature only work with a
restricted set of types, namely enum
and submodules
and any composed
forms of them.
Extensible option types can be used for enum
options that affects
multiple modules, or as an alternative to related enable
options.
As an example, we will take the case of display managers. There is a central display manager module for generic display manager options and a module file per display manager backend (sddm, gdm …).
There are two approaches we could take with this module structure:
Configuring the display managers independently by adding an enable option to every display manager module backend. (NixOS)
Configuring the display managers in the central module by adding an option to select which display manager backend to use.
Both approaches have problems.
Making backends independent can quickly become hard to manage. For
display managers, there can only be one enabled at a time, but the
type system cannot enforce this restriction as there is no relation
between each backend’s enable
option. As a result, this restriction
has to be done explicitly by adding assertions in each display manager
backend module.
On the other hand, managing the display manager backends in the central module will require changing the central module option every time a new backend is added or removed.
By using extensible option types, it is possible to create a placeholder
option in the central module
(Example: Extensible type placeholder in the service module),
and to extend it in each backend module
(Example: Extending services.xserver.displayManager.enable
in the gdm
module,
Example: Extending services.xserver.displayManager.enable
in the sddm
module).
As a result, displayManager.enable
option values can be added without
changing the main service module file and the type system automatically
enforces that there can only be a single display manager enabled.
{
services.xserver.displayManager.enable = mkOption {
description = "Display manager to use";
type = with types; nullOr (enum [ ]);
};
}
services.xserver.displayManager.enable
in the gdm
module{
services.xserver.displayManager.enable = mkOption {
type = with types; nullOr (enum [ "gdm" ]);
};
}
services.xserver.displayManager.enable
in the sddm
module{
services.xserver.displayManager.enable = mkOption {
type = with types; nullOr (enum [ "sddm" ]);
};
}
The placeholder declaration is a standard mkOption
declaration, but it
is important that extensible option declarations only use the type
argument.
Extensible option types work with any of the composed variants of enum
such as with types; nullOr (enum [ "foo" "bar" ])
or with types; listOf (enum [ "foo" "bar" ])
.
Option types are a way to put constraints on the values a module option can take. Types are also responsible of how values are merged in case of multiple value definitions.
Basic types are the simplest available types in the module system. Basic types include multiple string types that mainly differ in how definition merging is handled.
types.bool
A boolean, its values can be true
or false
.
All definitions must have the same value, after priorities. An error is thrown in case of a conflict.
types.boolByOr
A boolean, its values can be true
or false
.
The result is true
if any of multiple definitions is true
.
In other words, definitions are merged with the logical OR operator.
types.path
A filesystem path is anything that starts with a slash when
coerced to a string. Even if derivations can be considered as
paths, the more specific types.package
should be preferred.
types.pathInStore
A path that is contained in the Nix store. This can be a top-level store
path like pkgs.hello
or a descendant like "${pkgs.hello}/bin/hello"
.
types.package
A top-level store path. This can be an attribute set pointing to a store path, like a derivation or a flake input.
types.enum
l
One element of the list l
, e.g. types.enum [ "left" "right" ]
.
Multiple definitions cannot be merged.
If you want to pair these values with more information, possibly of distinct types, consider using a sum type.
types.anything
A type that accepts any value and recursively merges attribute sets together. This type is recommended when the option type is unknown.
types.anything
Two definitions of this type like
{
str = lib.mkDefault "foo";
pkg.hello = pkgs.hello;
fun.fun = x: x + 1;
}
{
str = lib.mkIf true "bar";
pkg.gcc = pkgs.gcc;
fun.fun = lib.mkForce (x: x + 2);
}
will get merged to
{
str = "bar";
pkg.gcc = pkgs.gcc;
pkg.hello = pkgs.hello;
fun.fun = x: x + 2;
}
types.raw
A type which doesn’t do any checking, merging or nested evaluation. It
accepts a single arbitrary value that is not recursed into, making it
useful for values coming from outside the module system, such as package
sets or arbitrary data. Options of this type are still evaluated according
to priorities and conditionals, so mkForce
, mkIf
and co. still work on
the option value itself, but not for any value nested within it. This type
should only be used when checking, merging and nested evaluation are not
desirable.
types.optionType
The type of an option’s type. Its merging operation ensures that nested
options have the correct file location annotated, and that if possible,
multiple option definitions are correctly merged together. The main use
case is as the type of the _module.freeformType
option.
types.attrs
A free-form attribute set.
This type will be deprecated in the future because it doesn’t
recurse into attribute sets, silently drops earlier attribute
definitions, and doesn’t discharge lib.mkDefault
, lib.mkIf
and co. For allowing arbitrary attribute sets, prefer
types.attrsOf types.anything
instead which doesn’t have these
problems.
types.pkgs
A type for the top level Nixpkgs package set.
types.int
A signed integer.
types.ints.{s8, s16, s32}
Signed integers with a fixed length (8, 16 or 32 bits). They go from
−2^n/2 to
2^n/2−1 respectively (e.g. −128
to
127
for 8 bits).
types.ints.unsigned
An unsigned integer (that is >= 0).
types.ints.{u8, u16, u32}
Unsigned integers with a fixed length (8, 16 or 32 bits). They go
from 0 to 2^n−1 respectively (e.g. 0
to 255
for 8 bits).
types.ints.between
lowest highest
An integer between lowest
and highest
(both inclusive).
types.ints.positive
A positive integer (that is > 0).
types.port
A port number. This type is an alias to
types.ints.u16
.
types.float
A floating point number.
Converting a floating point number to a string with toString
or toJSON
may result in precision loss.
types.number
Either a signed integer or a floating point number. No implicit conversion is done between the two types, and multiple equal definitions will only be merged if they have the same type.
types.numbers.between
lowest highest
An integer or floating point number between lowest
and highest
(both inclusive).
types.numbers.nonnegative
A nonnegative integer or floating point number (that is >= 0).
types.numbers.positive
A positive integer or floating point number (that is > 0).
types.str
A string. Multiple definitions cannot be merged.
types.separatedString
sep
A string. Multiple definitions are concatenated with sep
, e.g.
types.separatedString "|"
.
types.lines
A string. Multiple definitions are concatenated with a new line
"\n"
.
types.commas
A string. Multiple definitions are concatenated with a comma ","
.
types.envVar
A string. Multiple definitions are concatenated with a colon ":"
.
types.strMatching
A string matching a specific regular expression. Multiple
definitions cannot be merged. The regular expression is processed
using builtins.match
.
Submodules are detailed in Submodule.
types.submodule
o
A set of sub options o
. o
can be an attribute set, a function
returning an attribute set, or a path to a file containing such a
value. Submodules are used in composed types to create modular
options. This is equivalent to
types.submoduleWith { modules = toList o; shorthandOnlyDefinesConfig = true; }
.
types.submoduleWith
{ modules
, specialArgs
? {}, shorthandOnlyDefinesConfig
? false }Like types.submodule
, but more flexible and with better defaults.
It has parameters
modules
A list of modules to use by default for this
submodule type. This gets combined with all option definitions
to build the final list of modules that will be included.
Only options defined with this argument are included in rendered documentation.
specialArgs
An attribute set of extra arguments to be passed
to the module functions. The option _module.args
should be
used instead for most arguments since it allows overriding.
specialArgs
should only be used for arguments that can’t go
through the module fixed-point, because of infinite recursion or
other problems. An example is overriding the lib
argument,
because lib
itself is used to define _module.args
, which
makes using _module.args
to define it impossible.
shorthandOnlyDefinesConfig
Whether definitions of this type
should default to the config
section of a module (see
Example: Structure of NixOS Modules)
if it is an attribute set. Enabling this only has a benefit
when the submodule defines an option named config
or options
.
In such a case it would allow the option to be set with
the-submodule.config = "value"
instead of requiring
the-submodule.config.config = "value"
. This is because
only when modules don’t set the config
or options
keys, all keys are interpreted as option definitions in the
config
section. Enabling this option implicitly puts all
attributes in the config
section.
With this option enabled, defining a non-config
section
requires using a function:
the-submodule = { ... }: { options = { ... }; }
.
types.deferredModule
Whereas submodule
represents an option tree, deferredModule
represents
a module value, such as a module file or a configuration.
It can be set multiple times.
Module authors can use its value in imports
, in submoduleWith
’s modules
or in evalModules
’ modules
parameter, among other places.
Note that imports
must be evaluated before the module fixpoint. Because
of this, deferred modules can only be imported into “other” fixpoints, such
as submodules.
One use case for this type is the type of a “default” module that allow the
user to affect all submodules in an attrsOf submodule
at once. This is
more convenient and discoverable than expecting the module user to
type-merge with the attrsOf submodule
option.
A union of types is a type such that a value is valid when it is valid for at least one of those types.
If some values are instances of more than one of the types, it is not possible to distinguish which type they are meant to be instances of. If that’s needed, consider using a sum type.
types.either
t1 t2
Type t1
or type t2
, e.g. with types; either int str
.
Multiple definitions cannot be merged.
types.oneOf
[ t1 t2
… ]Type t1
or type t2
and so forth, e.g.
with types; oneOf [ int str bool ]
. Multiple definitions cannot be
merged.
types.nullOr
t
null
or type t
. Multiple definitions are merged according to
type t
.
A sum type can be thought of, conceptually, as a types.enum
where each valid item is paired with at least a type, through some value syntax.
Nix does not have a built-in syntax for this pairing of a label and a type or value, so sum types may be represented in multiple ways.
If the you’re interested in can be distinguished without a label, you may simplify your value syntax with a union type instead.
types.attrTag
{ attr1 = option1; attr2 = option2; ... }
An attribute set containing one attribute, whose name must be picked from
the attribute set (attr1
, etc) and whose value consists of definitions that are valid for the corresponding option (option1
, etc).
This type appears in the documentation as attribute-tagged union.
Example:
{ lib, ... }:
let inherit (lib) type mkOption;
in {
options.toyRouter.rules = mkOption {
description = ''
Rules for a fictional packet routing service.
'';
type = types.attrsOf (
types.attrTag {
bounce = mkOption {
description = "Send back a packet explaining why it wasn't forwarded.";
type = types.submodule {
options.errorMessage = mkOption { … };
};
};
forward = mkOption {
description = "Forward the packet.";
type = types.submodule {
options.destination = mkOption { … };
};
};
ignore = types.mkOption {
description = "Drop the packet without sending anything back.";
type = types.submodule {};
};
});
};
config.toyRouter.rules = {
http = {
bounce = {
errorMessage = "Unencrypted HTTP is banned. You must always use https://.";
};
};
ssh = { drop = {}; };
};
}
Composed types are types that take a type as parameter. listOf int
and either int str
are examples of composed types.
types.listOf
t
A list of t
type, e.g. types.listOf int
. Multiple definitions are merged with list concatenation.
types.attrsOf
t
An attribute set of where all the values are of t
type. Multiple
definitions result in the joined attribute set.
This type is strict in its values, which in turn means attributes
cannot depend on other attributes. See types.lazyAttrsOf
for a lazy version.
types.lazyAttrsOf
t
An attribute set of where all the values are of t
type. Multiple
definitions result in the joined attribute set. This is the lazy
version of types.attrsOf
, allowing attributes to depend on each other.
This version does not fully support conditional definitions! With an
option foo
of this type and a definition
foo.attr = lib.mkIf false 10
, evaluating foo ? attr
will return
true
even though it should be false. Accessing the value will then
throw an error. For types t
that have an emptyValue
defined,
that value will be returned instead of throwing an error. So if the
type of foo.attr
was lazyAttrsOf (nullOr int)
, null
would be
returned instead for the same mkIf false
definition.
types.uniq
t
Ensures that type t
cannot be merged. It is used to ensure option
definitions are provided only once.
types.unique
{ message = m }
t
Ensures that type t
cannot be merged. Prints the message m
, after
the line The option <option path> is defined multiple times.
and before
a list of definition locations.
types.coercedTo
from f to
Type to
or type from
which will be coerced to type to
using
function f
which takes an argument of type from
and return a
value of type to
. Can be used to preserve backwards compatibility
of an option if its type was changed.
submodule
is a very powerful type that defines a set of sub-options
that are handled like a separate module.
It takes a parameter o
, that should be a set, or a function returning
a set with an options
key defining the sub-options. Submodule option
definitions are type-checked accordingly to the options
declarations.
Of course, you can nest submodule option definitions for even higher
modularity.
The option set can be defined directly (Example: Directly defined submodule) or as reference (Example: Submodule defined as a reference).
Note that even if your submodule’s options all have a default value, you will still need to provide a default value (e.g. an empty attribute set) if you want to allow users to leave it undefined.
{
options.mod = mkOption {
description = "submodule example";
type = with types; submodule {
options = {
foo = mkOption {
type = int;
};
bar = mkOption {
type = str;
};
};
};
};
}
let
modOptions = {
options = {
foo = mkOption {
type = int;
};
bar = mkOption {
type = int;
};
};
};
in
{
options.mod = mkOption {
description = "submodule example";
type = with types; submodule modOptions;
};
}
The submodule
type is especially interesting when used with composed
types like attrsOf
or listOf
. When composed with listOf
(Example: Declaration of a list of submodules), submodule
allows
multiple definitions of the submodule option set
(Example: Definition of a list of submodules).
{
options.mod = mkOption {
description = "submodule example";
type = with types; listOf (submodule {
options = {
foo = mkOption {
type = int;
};
bar = mkOption {
type = str;
};
};
});
};
}
{
config.mod = [
{ foo = 1; bar = "one"; }
{ foo = 2; bar = "two"; }
];
}
When composed with attrsOf
(Example: Declaration of attribute sets of submodules), submodule
allows
multiple named definitions of the submodule option set
(Example: Definition of attribute sets of submodules).
{
options.mod = mkOption {
description = "submodule example";
type = with types; attrsOf (submodule {
options = {
foo = mkOption {
type = int;
};
bar = mkOption {
type = str;
};
};
});
};
}
{
config.mod.one = { foo = 1; bar = "one"; };
config.mod.two = { foo = 2; bar = "two"; };
}
Types are mainly characterized by their check
and merge
functions.
check
The function to type check the value. Takes a value as parameter and
return a boolean. It is possible to extend a type check with the
addCheck
function (Example: Adding a type check),
or to fully override the check function
(Example: Overriding a type check).
{
byte = mkOption {
description = "An integer between 0 and 255.";
type = types.addCheck types.int (x: x >= 0 && x <= 255);
};
}
{
nixThings = mkOption {
description = "words that start with 'nix'";
type = types.str // {
check = (x: lib.hasPrefix "nix" x);
};
};
}
merge
Function to merge the options values when multiple values are set.
The function takes two parameters, loc
the option path as a list
of strings, and defs
the list of defined values as a list. It is
possible to override a type merge function for custom needs.
Custom types can be created with the mkOptionType
function. As type
creation includes some more complex topics such as submodule handling,
it is recommended to get familiar with types.nix
code before creating
a new type.
The only required parameter is name
.
name
A string representation of the type function name.
description
Description of the type used in documentation. Give information of the type and any of its arguments.
check
A function to type check the definition value. Takes the definition
value as a parameter and returns a boolean indicating the type check
result, true
for success and false
for failure.
merge
A function to merge multiple definitions values. Takes two parameters:
loc
The option path as a list of strings, e.g. ["boot" "loader "grub" "enable"]
.
defs
The list of sets of defined value
and file
where the value
was defined, e.g. [ { file = "/foo.nix"; value = 1; } { file = "/bar.nix"; value = 2 } ]
. The merge
function should return the merged value
or throw an error in case the values are impossible or not meant
to be merged.
getSubOptions
For composed types that can take a submodule as type parameter, this
function generate sub-options documentation. It takes the current
option prefix as a list and return the set of sub-options. Usually
defined in a recursive manner by adding a term to the prefix, e.g.
prefix: elemType.getSubOptions (prefix ++ ["prefix"])
where "prefix"
is the newly added prefix.
getSubModules
For composed types that can take a submodule as type parameter, this
function should return the type parameters submodules. If the type
parameter is called elemType
, the function should just recursively
look into submodules by returning elemType.getSubModules;
.
substSubModules
For composed types that can take a submodule as type parameter, this
function can be used to substitute the parameter of a submodule
type. It takes a module as parameter and return the type with the
submodule options substituted. It is usually defined as a type
function call with a recursive call to substSubModules
, e.g for a
type composedType
that take an elemtype
type parameter, this
function should be defined as m: composedType (elemType.substSubModules m)
.
typeMerge
A function to merge multiple type declarations. Takes the type to
merge functor
as parameter. A null
return value means that type
cannot be merged.
f
The type to merge functor
.
Note: There is a generic defaultTypeMerge
that work with most of
value and composed types.
functor
An attribute set representing the type. It is used for type operations and has the following keys:
type
The type function.
wrapped
Holds the type parameter for composed types.
payload
Holds the value parameter for value types. The types that have a
payload
are the enum
, separatedString
and submodule
types.
binOp
A binary operation that can merge the payloads of two same types. Defined as a function that take two payloads as parameters and return the payloads merged.
Option definitions are generally straight-forward bindings of values to option names, like
{
config = {
services.httpd.enable = true;
};
}
However, sometimes you need to wrap an option definition or set of option definitions in a property to achieve certain effects:
If a set of option definitions is conditional on the value of another
option, you may need to use mkIf
. Consider, for instance:
{
config = if config.services.httpd.enable then {
environment.systemPackages = [ /* ... */ ];
# ...
} else {};
}
This definition will cause Nix to fail with an “infinite recursion”
error. Why? Because the value of config.services.httpd.enable
depends
on the value being constructed here. After all, you could also write the
clearly circular and contradictory:
{
config = if config.services.httpd.enable then {
services.httpd.enable = false;
} else {
services.httpd.enable = true;
};
}
The solution is to write:
{
config = mkIf config.services.httpd.enable {
environment.systemPackages = [ /* ... */ ];
# ...
};
}
The special function mkIf
causes the evaluation of the conditional to
be “pushed down” into the individual definitions, as if you had written:
{
config = {
environment.systemPackages = if config.services.httpd.enable then [ /* ... */ ] else [];
# ...
};
}
A module can override the definitions of an option in other modules by
setting an override priority. All option definitions that do not have the lowest
priority value are discarded. By default, option definitions have
priority 100 and option defaults have priority 1500.
You can specify an explicit priority by using mkOverride
, e.g.
{
services.openssh.enable = mkOverride 10 false;
}
This definition causes all other definitions with priorities above 10 to
be discarded. The function mkForce
is equal to mkOverride 50
, and
mkDefault
is equal to mkOverride 1000
.
It is also possible to influence the order in which the definitions for an option are
merged by setting an order priority with mkOrder
. The default order priority is 1000.
The functions mkBefore
and mkAfter
are equal to mkOrder 500
and mkOrder 1500
, respectively.
As an example,
{
hardware.firmware = mkBefore [ myFirmware ];
}
This definition ensures that myFirmware
comes before other unordered
definitions in the final list value of hardware.firmware
.
Note that this is different from override priorities: setting an order does not affect whether the definition is included or not.
In conjunction with mkIf
, it is sometimes useful for a module to
return multiple sets of option definitions, to be merged together as if
they were declared in separate modules. This can be done using
mkMerge
:
{
config = mkMerge
[ # Unconditional stuff.
{ environment.systemPackages = [ /* ... */ ];
}
# Conditional stuff.
(mkIf config.services.bla.enable {
environment.systemPackages = [ /* ... */ ];
})
];
}
When configuration problems are detectable in a module, it is a good idea to write an assertion or warning. Doing so provides clear feedback to the user and prevents errors after the build.
Although Nix has the abort
and builtins.trace
functions to perform such tasks, they are not ideally suited for NixOS modules. Instead of these functions, you can declare your warnings and assertions using the NixOS module system.
This is an example of using warnings
.
{ config, lib, ... }:
{
config = lib.mkIf config.services.foo.enable {
warnings =
if config.services.foo.bar
then [ ''You have enabled the bar feature of the foo service.
This is known to cause some specific problems in certain situations.
'' ]
else [];
};
}
This example, extracted from the syslogd
module shows how to use assertions
. Since there can only be one active syslog daemon at a time, an assertion is useful to prevent such a broken system from being built.
{ config, lib, ... }:
{
config = lib.mkIf config.services.syslogd.enable {
assertions =
[ { assertion = !config.services.rsyslogd.enable;
message = "rsyslogd conflicts with syslogd";
}
];
};
}
Like Nix packages, NixOS modules can declare meta-attributes to provide
extra information. Module meta attributes are defined in the meta.nix
special module.
meta
is a top level attribute like options
and config
. Available
meta-attributes are maintainers
, doc
, and buildDocsInSandbox
.
Each of the meta-attributes must be defined at most once per module file.
{ config, lib, pkgs, ... }:
{
options = {
# ...
};
config = {
# ...
};
meta = {
maintainers = with lib.maintainers; [ ericsagnes ];
doc = ./default.md;
buildDocsInSandbox = true;
};
}
maintainers
contains a list of the module maintainers.
doc
points to a valid Nixpkgs-flavored CommonMark file containing the module
documentation. Its contents is automatically added to
Configuration. Changes to a module documentation have to
be checked to not break building the NixOS manual:
$ nix-build nixos/release.nix -A manual.x86_64-linux
buildDocsInSandbox
indicates whether the option documentation for the
module can be built in a derivation sandbox. This option is currently only
honored for modules shipped by nixpkgs. User modules and modules taken from
NIXOS_EXTRA_MODULE_PATH
are always built outside of the sandbox, as has
been the case in previous releases.
Building NixOS option documentation in a sandbox allows caching of the built
documentation, which greatly decreases the amount of time needed to evaluate
a system configuration that has NixOS documentation enabled. The sandbox also
restricts which attributes may be referenced by documentation attributes
(such as option descriptions) to the options
and lib
module arguments and
the pkgs.formats
attribute of the pkgs
argument, config
and the rest of
pkgs
are disallowed and will cause doc build failures when used. This
restriction is necessary because we cannot reproduce the full nixpkgs
instantiation with configuration and overlays from a system configuration
inside the sandbox. The options
argument only includes options of modules
that are also built inside the sandbox, referencing an option of a module
that isn’t built in the sandbox is also forbidden.
The default is true
and should usually not be changed; set it to false
only if the module requires access to pkgs
in its documentation (e.g.
because it loads information from a linked package to build an option type)
or if its documentation depends on other modules that also aren’t sandboxed
(e.g. by using types defined in the other module).
Sometimes NixOS modules need to be used in configuration but exist outside of Nixpkgs. These modules can be imported:
{ config, lib, pkgs, ... }:
{
imports =
[ # Use a locally-available module definition in
# ./example-module/default.nix
./example-module
];
services.exampleModule.enable = true;
}
The environment variable NIXOS_EXTRA_MODULE_PATH
is an absolute path
to a NixOS module that is included alongside the Nixpkgs NixOS modules.
Like any NixOS module, this module can import additional modules:
# ./module-list/default.nix
[
./example-module1
./example-module2
]
# ./extra-module/default.nix
{ imports = import ./module-list.nix; }
# NIXOS_EXTRA_MODULE_PATH=/absolute/path/to/extra-module
{ config, lib, pkgs, ... }:
{
# No `imports` needed
services.exampleModule1.enable = true;
}
Modules that are imported can also be disabled. The option declarations, config implementation and the imports of a disabled module will be ignored, allowing another to take its place. This can be used to import a set of modules from another channel while keeping the rest of the system on a stable release.
disabledModules
is a top level attribute like imports
, options
and
config
. It contains a list of modules that will be disabled. This can
either be:
the full path to the module,
or a string with the filename relative to the modules path (eg. <nixpkgs/nixos/modules> for nixos),
or an attribute set containing a specific key
attribute.
The latter allows some modules to be disabled, despite them being distributed
via attributes instead of file paths. The key
should be globally unique, so
it is recommended to include a file path in it, or rely on a framework to do it
for you.
This example will replace the existing postgresql module with the version defined in the nixos-unstable channel while keeping the rest of the modules and packages from the original nixos channel. This only overrides the module definition, this won’t use postgresql from nixos-unstable unless explicitly configured to do so.
{ config, lib, pkgs, ... }:
{
disabledModules = [ "services/databases/postgresql.nix" ];
imports =
[ # Use postgresql service from nixos-unstable channel.
# sudo nix-channel --add https://nixos.org/channels/nixos-unstable nixos-unstable
<nixos-unstable/nixos/modules/services/databases/postgresql.nix>
];
services.postgresql.enable = true;
}
This example shows how to define a custom module as a replacement for an existing module. Importing this module will disable the original module without having to know its implementation details.
{ config, lib, pkgs, ... }:
let
inherit (lib) mkIf mkOption types;
cfg = config.programs.man;
in
{
disabledModules = [ "services/programs/man.nix" ];
options = {
programs.man.enable = mkOption {
type = types.bool;
default = true;
description = "Whether to enable manual pages.";
};
};
config = mkIf cfg.enabled {
warnings = [ "disabled manpages for production deployments." ];
};
}
Freeform modules allow you to define values for option paths that have
not been declared explicitly. This can be used to add attribute-specific
types to what would otherwise have to be attrsOf
options in order to
accept all attribute names.
This feature can be enabled by using the attribute freeformType
to
define a freeform type. By doing this, all assignments without an
associated option will be merged using the freeform type and combined
into the resulting config
set. Since this feature nullifies name
checking for entire option trees, it is only recommended for use in
submodules.
The following shows a submodule assigning a freeform type that allows
arbitrary attributes with str
values below settings
, but also
declares an option for the settings.port
attribute to have it
type-checked and assign a default value. See
Example: Declaring a type-checked settings
attribute
for a more complete example.
{ lib, config, ... }: {
options.settings = lib.mkOption {
type = lib.types.submodule {
freeformType = with lib.types; attrsOf str;
# We want this attribute to be checked for the correct type
options.port = lib.mkOption {
type = lib.types.port;
# Declaring the option also allows defining a default value
default = 8080;
};
};
};
}
And the following shows what such a module then allows
{
# Not a declared option, but the freeform type allows this
settings.logLevel = "debug";
# Not allowed because the the freeform type only allows strings
# settings.enable = true;
# Allowed because there is a port option declared
settings.port = 80;
# Not allowed because the port option doesn't allow strings
# settings.port = "443";
}
Freeform attributes cannot depend on other attributes of the same set without infinite recursion:
{
# This throws infinite recursion encountered
settings.logLevel = lib.mkIf (config.settings.port == 80) "debug";
}
To prevent this, declare options for all attributes that need to depend
on others. For above example this means to declare logLevel
to be an
option.
Many programs have configuration files where program-specific settings can be declared. File formats can be separated into two categories:
Nix-representable ones: These can trivially be mapped to a subset of
Nix syntax. E.g. JSON is an example, since its values like
{"foo":{"bar":10}}
can be mapped directly to Nix:
{ foo = { bar = 10; }; }
. Other examples are INI, YAML and TOML.
The following section explains the convention for these settings.
Non-nix-representable ones: These can’t be trivially mapped to a
subset of Nix syntax. Most generic programming languages are in this
group, e.g. bash, since the statement if true; then echo hi; fi
doesn’t have a trivial representation in Nix.
Currently there are no fixed conventions for these, but it is common
to have a configFile
option for setting the configuration file
path directly. The default value of configFile
can be an
auto-generated file, with convenient options for controlling the
contents. For example an option of type attrsOf str
can be used
for representing environment variables which generates a section
like export FOO="foo"
. Often it can also be useful to also include
an extraConfig
option of type lines
to allow arbitrary text
after the autogenerated part of the file.
By convention, formats like this are handled with a generic settings
option, representing the full program configuration as a Nix value. The
type of this option should represent the format. The most common formats
have a predefined type and string generator already declared under
pkgs.formats
:
pkgs.formats.javaProperties
{ comment
? "Generated with Nix"
}A function taking an attribute set with values
comment
A string to put at the start of the file in a comment. It can have multiple lines.
It returns the type
: attrsOf str
and a function
generate
to build a Java .properties
file, taking
care of the correct escaping, etc.
pkgs.formats.json
{ }A function taking an empty attribute set (for future extensibility)
and returning a set with JSON-specific attributes type
and
generate
as specified below.
pkgs.formats.yaml
{ }A function taking an empty attribute set (for future extensibility)
and returning a set with YAML-specific attributes type
and
generate
as specified below.
pkgs.formats.ini
{ listsAsDuplicateKeys
? false, listToValue
? null, ... }A function taking an attribute set with values
listsAsDuplicateKeys
A boolean for controlling whether list values can be used to represent duplicate INI keys
listToValue
A function for turning a list of values into a single value.
It returns a set with INI-specific attributes type
and generate
as specified below.
The type of the input is an attrset of sections; key-value pairs where
the key is the section name and the value is the corresponding content
which is also an attrset of key-value pairs for the actual key-value
mappings of the INI format.
The values of the INI atoms are subject to the above parameters (e.g. lists
may be transformed into multiple key-value pairs depending on
listToValue
).
pkgs.formats.iniWithGlobalSection
{ listsAsDuplicateKeys
? false, listToValue
? null, ... }A function taking an attribute set with values
listsAsDuplicateKeys
A boolean for controlling whether list values can be used to represent duplicate INI keys
listToValue
A function for turning a list of values into a single value.
It returns a set with INI-specific attributes type
and generate
as specified below.
The type of the input is an attrset of the structure
{ sections = {}; globalSection = {}; }
where sections are several
sections as with pkgs.formats.ini and globalSection being just a single
attrset of key-value pairs for a single section, the global section which
preceedes the section definitions.
pkgs.formats.toml
{ }A function taking an empty attribute set (for future extensibility)
and returning a set with TOML-specific attributes type
and
generate
as specified below.
pkgs.formats.elixirConf { elixir ? pkgs.elixir }
A function taking an attribute set with values
elixir
The Elixir package which will be used to format the generated output
It returns a set with Elixir-Config-specific attributes type
, lib
, and
generate
as specified below.
The lib
attribute contains functions to be used in settings, for
generating special Elixir values:
mkRaw elixirCode
Outputs the given string as raw Elixir code
mkGetEnv { envVariable, fallback ? null }
Makes the configuration fetch an environment variable at runtime
mkAtom atom
Outputs the given string as an Elixir atom, instead of the default
Elixir binary string. Note: lowercase atoms still needs to be prefixed
with :
mkTuple array
Outputs the given array as an Elixir tuple, instead of the default Elixir list
mkMap attrset
Outputs the given attribute set as an Elixir map, instead of the default Elixir keyword list
pkgs.formats.php { finalVariable }
A function taking an attribute set with values
finalVariable
The variable that will store generated expression (usually config
). If set to null
, generated expression will contain return
.
It returns a set with PHP-Config-specific attributes type
, lib
, and
generate
as specified below.
The lib
attribute contains functions to be used in settings, for
generating special PHP values:
mkRaw phpCode
Outputs the given string as raw PHP code
mkMixedArray list set
Creates PHP array that contains both indexed and associative values. For example, lib.mkMixedArray [ "hello" "world" ] { "nix" = "is-great"; }
returns ['hello', 'world', 'nix' => 'is-great']
These functions all return an attribute set with these values:
type
A module system type representing a value of the format
lib
Utility functions for convenience, or special interactions with the format.
This attribute is optional. It may contain inside a types
attribute
containing types specific to this format.
generate
filename jsonValue
A function that can render a value of the format to a file. Returns a file path.
This function puts the value contents in the Nix store. So this should be avoided for secrets.
settings
optionThe following shows a module for an example program that uses a JSON configuration file. It demonstrates how above values can be used, along with some other related best practices. See the comments for explanations.
{ options, config, lib, pkgs, ... }:
let
cfg = config.services.foo;
# Define the settings format used for this program
settingsFormat = pkgs.formats.json {};
in {
options.services.foo = {
enable = lib.mkEnableOption "foo service";
settings = lib.mkOption {
# Setting this type allows for correct merging behavior
type = settingsFormat.type;
default = {};
description = ''
Configuration for foo, see
<link xlink:href="https://example.com/docs/foo"/>
for supported settings.
'';
};
};
config = lib.mkIf cfg.enable {
# We can assign some default settings here to make the service work by just
# enabling it. We use `mkDefault` for values that can be changed without
# problems
services.foo.settings = {
# Fails at runtime without any value set
log_level = lib.mkDefault "WARN";
# We assume systemd's `StateDirectory` is used, so we require this value,
# therefore no mkDefault
data_path = "/var/lib/foo";
# Since we use this to create a user we need to know the default value at
# eval time
user = lib.mkDefault "foo";
};
environment.etc."foo.json".source =
# The formats generator function takes a filename and the Nix value
# representing the format value and produces a filepath with that value
# rendered in the format
settingsFormat.generate "foo-config.json" cfg.settings;
# We know that the `user` attribute exists because we set a default value
# for it above, allowing us to use it without worries here
users.users.${cfg.settings.user} = { isSystemUser = true; };
# ...
};
}
Some settings
attributes may deserve some extra care. They may need a
different type, default or merging behavior, or they are essential
options that should show their documentation in the manual. This can be
done using the section called “Freeform modules”.
We extend above example using freeform modules to declare an option for the port, which will enforce it to be a valid integer and make it show up in the manual.
settings
attribute{
settings = lib.mkOption {
type = lib.types.submodule {
freeformType = settingsFormat.type;
# Declare an option for the port such that the type is checked and this option
# is shown in the manual.
options.port = lib.mkOption {
type = lib.types.port;
default = 8080;
description = ''
Which port this service should listen on.
'';
};
};
default = {};
description = ''
Configuration for Foo, see
<link xlink:href="https://example.com/docs/foo"/>
for supported values.
'';
};
}
With the command nix-build
, you can build specific parts of your NixOS
configuration. This is done as follows:
$ cd /path/to/nixpkgs/nixos
$ nix-build -A config.option
where option
is a NixOS option with type “derivation” (i.e. something
that can be built). Attributes of interest include:
system.build.toplevel
The top-level option that builds the entire NixOS system. Everything
else in your configuration is indirectly pulled in by this option.
This is what nixos-rebuild
builds and what /run/current-system
points to afterwards.
A shortcut to build this is:
$ nix-build -A system
system.build.manual.manualHTML
The NixOS manual.
system.build.etc
A tree of symlinks that form the static parts of /etc
.
system.build.initialRamdisk
, system.build.kernel
The initial ramdisk and kernel of the system. This allows a quick
way to test whether the kernel and the initial ramdisk boot
correctly, by using QEMU’s -kernel
and -initrd
options:
$ nix-build -A config.system.build.initialRamdisk -o initrd
$ nix-build -A config.system.build.kernel -o kernel
$ qemu-system-x86_64 -kernel ./kernel/bzImage -initrd ./initrd/initrd -hda /dev/null
system.build.nixos-rebuild
, system.build.nixos-install
, system.build.nixos-generate-config
These build the corresponding NixOS commands.
systemd.units.unit-name.unit
This builds the unit with the specified name. Note that since unit
names contain dots (e.g. httpd.service
), you need to put them
between quotes, like this:
$ nix-build -A 'config.systemd.units."httpd.service".unit'
You can also test individual units, without rebuilding the whole
system, by putting them in /run/systemd/system
:
$ cp $(nix-build -A 'config.systemd.units."httpd.service".unit')/httpd.service \
/run/systemd/system/tmp-httpd.service
# systemctl daemon-reload
# systemctl start tmp-httpd.service
Note that the unit must not have the same name as any unit in
/etc/systemd/system
since those take precedence over
/run/systemd/system
. That’s why the unit is installed as
tmp-httpd.service
here.
Table of Contents
Bootspec is a experimental feature, introduced in the RFC-0125 proposal, the reference implementation can be found there in order to standardize bootloader support and advanced boot workflows such as SecureBoot and potentially more.
You can enable the creation of bootspec documents through boot.bootspec.enable = true
, which will prompt a warning until RFC-0125 is officially merged.
The bootspec schema is versioned and validated against a CUE schema file which should considered as the source of truth for your applications.
You will find the current version here.
Bootspec cannot account for all usecases.
For this purpose, Bootspec offers a generic extension facility boot.bootspec.extensions
which can be used to inject any data needed for your usecases.
An example for SecureBoot is to get the Nix store path to /etc/os-release
in order to bake it into a unified kernel image:
{ config, lib, ... }: {
boot.bootspec.extensions = {
"org.secureboot.osRelease" = config.environment.etc."os-release".source;
};
}
To reduce incompatibility and prevent names from clashing between applications, it is highly recommended to use a unique namespace for your extensions.
It is possible to enable your own bootloader through boot.loader.external.installHook
which can wrap an existing bootloader.
Currently, there is no good story to compose existing bootloaders to enrich their features, e.g. SecureBoot, etc. It will be necessary to reimplement or reuse existing parts.
Table of Contents
Running nixos-rebuild switch
is one of the more common tasks under NixOS.
This chapter explains some of the internals of this command to make it simpler
for new module developers to configure their units correctly and to make it
easier to understand what is happening and why for curious administrators.
nixos-rebuild
, like many deployment solutions, calls switch-to-configuration
which resides in a NixOS system at $out/bin/switch-to-configuration
. The
script is called with the action that is to be performed like switch
, test
,
boot
. There is also the dry-activate
action which does not really perform
the actions but rather prints what it would do if you called it with test
.
This feature can be used to check what service states would be changed if the
configuration was switched to.
If the action is switch
or boot
, the bootloader is updated first so the
configuration will be the next one to boot. Unless NIXOS_NO_SYNC
is set to
1
, /nix/store
is synced to disk.
If the action is switch
or test
, the currently running system is inspected
and the actions to switch to the new system are calculated. This process takes
two data sources into account: /etc/fstab
and the current systemd status.
Mounts and swaps are read from /etc/fstab
and the corresponding actions are
generated. If the options of a mount are modified, for example, the proper .mount
unit is reloaded (or restarted if anything else changed and it’s neither the root
mount or the nix store). The current systemd state is inspected, the difference
between the current system and the desired configuration is calculated and
actions are generated to get to this state. There are a lot of nuances that can
be controlled by the units which are explained here.
After calculating what should be done, the actions are carried out. The order of actions is always the same:
Stop units (systemctl stop
)
Run activation script ($out/activate
)
See if the activation script requested more units to restart
Restart systemd if needed (systemd daemon-reexec
)
Forget about the failed state of units (systemctl reset-failed
)
Reload systemd (systemctl daemon-reload
)
Reload systemd user instances (systemctl --user daemon-reload
)
Reactivate sysinit (systemctl restart sysinit-reactivation.target
)
Reload units (systemctl reload
)
Restart units (systemctl restart
)
Start units (systemctl start
)
Inspect what changed during these actions and print units that failed and that were newly started
By default, some units are filtered from the outputs to make it less spammy.
This can be disabled for development or testing by setting the environment variable
STC_DISPLAY_ALL_UNITS=1
Most of these actions are either self-explaining but some of them have to do with our units or the activation script. For this reason, these topics are explained in the next sections.
To figure out what units need to be started/stopped/restarted/reloaded, the
script first checks the current state of the system, similar to what systemctl list-units
shows. For each of the units, the script goes through the following
checks:
Is the unit file still in the new system? If not, stop the service unless
it sets X-StopOnRemoval
in the [Unit]
section to false
.
Is it a .target
unit? If so, start it unless it sets
RefuseManualStart
in the [Unit]
section to true
or X-OnlyManualStart
in the [Unit]
section to true
. Also stop the unit again unless it
sets X-StopOnReconfiguration
to false
.
Are the contents of the unit files different? They are compared by parsing
them and comparing their contents. If they are different but only
X-Reload-Triggers
in the [Unit]
section is changed, reload the unit.
The NixOS module system allows setting these triggers with the option
systemd.services.<name>.reloadTriggers. There are
some additional keys in the [Unit]
section that are ignored as well. If the
unit files differ in any way, the following actions are performed:
.path
and .slice
units are ignored. There is no need to restart them
since changes in their values are applied by systemd when systemd is
reloaded.
.mount
units are reloaded if only their Options
changed. If anything
else changed (like What
), they are restarted unless they are the mount
unit for /
or /nix
in which case they are reloaded to prevent the system
from crashing. Note that this is the case for .mount
units and not for
mounts from /etc/fstab
. These are explained in What happens during a system switch?.
.socket
units are currently ignored. This is to be fixed at a later
point.
The rest of the units (mostly .service
units) are then reloaded if
X-ReloadIfChanged
in the [Service]
section is set to true
(exposed
via systemd.services.<name>.reloadIfChanged).
A little exception is done for units that were deactivated in the meantime,
for example because they require a unit that got stopped before. These
are started instead of reloaded.
If the reload flag is not set, some more flags decide if the unit is
skipped. These flags are X-RestartIfChanged
in the [Service]
section
(exposed via
systemd.services.<name>.restartIfChanged),
RefuseManualStop
in the [Unit]
section, and X-OnlyManualStart
in the
[Unit]
section.
Further behavior depends on the unit having X-StopIfChanged
in the
[Service]
section set to true
(exposed via
systemd.services.<name>.stopIfChanged). This is
set to true
by default and must be explicitly turned off if not wanted.
If the flag is enabled, the unit is stopped and then started. If
not, the unit is restarted. The goal of the flag is to make sure that
the new unit never runs in the old environment which is still in place
before the activation script is run. This behavior is different when the
service is socket-activated, as outlined in the following steps.
The last thing that is taken into account is whether the unit is a service
and socket-activated. If X-StopIfChanged
is not set, the service
is restarted with the others. If it is set, both the service and the
socket are stopped and the socket is started, leaving socket
activation to start the service when it’s needed.
sysinit.target
is a systemd target that encodes system initialization (i.e. early startup). A
few units that need to run very early in the bootup process are ordered to
finish before this target is reached. Probably the most notable one of these is
systemd-tmpfiles-setup.service
. We will refer to these units as “sysinit
units”.
“Normal” systemd units, by default, are ordered AFTER sysinit.target
. In
other words, these “normal” units expect all services ordered before
sysinit.target
to have finished without explicity declaring this dependency
relationship for each dependency. See the systemd
bootup
for more details on the bootup process.
When restarting both a unit ordered before sysinit.target
as well as one
after, this presents a problem because they would be started at the same time
as they do not explicitly declare their dependency relations.
To solve this, NixOS has an artificial sysinit-reactivation.target
which
allows you to ensure that services ordered before sysinit.target
are
restarted correctly. This applies both to the ordering between these sysinit
services as well as ensuring that sysinit units are restarted before “normal”
units.
To make an existing sysinit service restart correctly during system switch, you have to declare:
{
systemd.services.my-sysinit = {
requiredBy = [ "sysinit-reactivation.target" ];
before = [ "sysinit-reactivation.target" ];
restartTriggers = [ config.environment.etc."my-sysinit.d".source ];
};
}
You need to configure appropriate restartTriggers
specific to your service.
The activation script is a bash script called to activate the new
configuration which resides in a NixOS system in $out/activate
. Since its
contents depend on your system configuration, the contents may differ.
This chapter explains how the script works in general and some common NixOS
snippets. Please be aware that the script is executed on every boot and system
switch, so tasks that can be performed in other places should be performed
there (for example letting a directory of a service be created by systemd using
mechanisms like StateDirectory
, CacheDirectory
, … or if that’s not
possible using preStart
of the service).
Activation scripts are defined as snippets using
system.activationScripts
. They can either be a simple multiline string
or an attribute set that can depend on other snippets. The builder for the
activation script will take these dependencies into account and order the
snippets accordingly. As a simple example:
{
system.activationScripts.my-activation-script = {
deps = [ "etc" ];
# supportsDryActivation = true;
text = ''
echo "Hallo i bims"
'';
};
}
This example creates an activation script snippet that is run after the etc
snippet. The special variable supportsDryActivation
can be set so the snippet
is also run when nixos-rebuild dry-activate
is run. To differentiate between
real and dry activation, the $NIXOS_ACTION
environment variable can be
read which is set to dry-activate
when a dry activation is done.
An activation script can write to special files instructing
switch-to-configuration
to restart/reload units. The script will take these
requests into account and will incorporate the unit configuration as described
above. This means that the activation script will “fake” a modified unit file
and switch-to-configuration
will act accordingly. By doing so, configuration
like systemd.services.<name>.restartIfChanged is
respected. Since the activation script is run after services are already
stopped, systemd.services.<name>.stopIfChanged
cannot be taken into account anymore and the unit is always restarted instead
of being stopped and started afterwards.
The files that can be written to are /run/nixos/activation-restart-list
and
/run/nixos/activation-reload-list
with their respective counterparts for
dry activation being /run/nixos/dry-activation-restart-list
and
/run/nixos/dry-activation-reload-list
. Those files can contain
newline-separated lists of unit names where duplicates are being ignored. These
files are not create automatically and activation scripts must take the
possibility into account that they have to create them first.
There are some snippets NixOS enables by default because disabling them would most likely break your system. This section lists a few of them and what they do:
binsh
creates /bin/sh
which points to the runtime shell
etc
sets up the contents of /etc
, this includes systemd units and
excludes /etc/passwd
, /etc/group
, and /etc/shadow
(which are managed by
the users
snippet)
hostname
sets the system’s hostname in the kernel (not in /etc
)
modprobe
sets the path to the modprobe
binary for module auto-loading
nix
prepares the nix store and adds a default initial channel
specialfs
is responsible for mounting filesystems like /proc
and sys
users
creates and removes users and groups by managing /etc/passwd
,
/etc/group
and /etc/shadow
. This also creates home directories
usrbinenv
creates /usr/bin/env
var
creates some directories in /var
that are not service-specific
wrappers
creates setuid wrappers like sudo
In certain systems, most notably image based appliances, updates are handled outside the system. This means that you do not need to rebuild your configuration on the system itself anymore.
If you want to build such a system, you can use the image-based-appliance
profile:
{ modulesPath, ... }: {
imports = [ "${modulesPath}/profiles/image-based-appliance.nix" ];
}
The most notable deviation of this profile from a standard NixOS configuration
is that after building it, you cannot switch to the configuration anymore.
The profile sets config.system.switch.enable = false;
, which excludes
switch-to-configuration
, the central script called by nixos-rebuild
, from
your system. Removing this script makes the image lighter and slightly more
secure.
/etc
via overlay filesystem This is experimental and requires a kernel version >= 6.6 because it uses new overlay features and relies on the new mount API.
Instead of using a custom perl script to activate /etc
, you activate it via an
overlay filesystem:
{
system.etc.overlay.enable = true;
}
Using an overlay has two benefits:
it removes a dependency on perl
it makes activation faster (up to a few seconds)
By default, the /etc
overlay is mounted writable (i.e. there is a writable
upper layer). However, you can also mount /etc
immutably (i.e. read-only) by
setting:
{
system.etc.overlay.mutable = false;
}
The overlay is atomically replaced during system switch. However, files that have been modified will NOT be overwritten. This is the biggest change compared to the perl-based system.
If you manually make changes to /etc
on your system and then switch to a new
configuration where system.etc.overlay.mutable = false;
, you will not be able
to see the previously made changes in /etc
anymore. However the changes are
not completely gone, they are still in the upperdir of the previous overlay in
/.rw-etc/upper
.
Table of Contents
As NixOS grows, so too does the need for a catalogue and explanation of its extensive functionality. Collecting pertinent information from disparate sources and presenting it in an accessible style would be a worthy contribution to the project.
The sources of the NixOS Manual are in the
nixos/doc/manual
subdirectory of the Nixpkgs repository.
You can quickly validate your edits with make
:
$ cd /path/to/nixpkgs/nixos/doc/manual
$ nix-shell
nix-shell$ devmode
Once you are done making modifications to the manual, it’s important to build it before committing. You can do that as follows:
nix-build nixos/release.nix -A manual.x86_64-linux
When this command successfully finishes, it will tell you where the
manual got generated. The HTML will be accessible through the result
symlink at ./result/share/doc/nixos/index.html
.
Table of Contents
When you add some feature to NixOS, you should write a test for it.
NixOS tests are kept in the directory nixos/tests
, and are executed
(using Nix) by a testing framework that automatically starts one or more
virtual machines containing the NixOS system(s) required for the test.
A NixOS test is a module that has the following structure:
{
# One or more machines:
nodes =
{ machine =
{ config, pkgs, ... }: { /* ... */ };
machine2 =
{ config, pkgs, ... }: { /* ... */ };
# …
};
testScript =
''
Python code…
'';
}
We refer to the whole test above as a test module, whereas the values
in nodes.<name>
are NixOS modules themselves.
The option testScript
is a piece of Python code that executes the
test (described below). During the test, it will start one or more
virtual machines, the configuration of which is described by
the option nodes
.
An example of a single-node test is
login.nix
.
It only needs a single machine to test whether users can log in
on the virtual console, whether device ownership is correctly maintained
when switching between consoles, and so on. An interesting multi-node test is
nfs/simple.nix
.
It uses two client nodes to test correct locking across server crashes.
Tests are invoked differently depending on whether the test is part of NixOS or lives in a different project.
Tests that are part of NixOS are added to nixos/tests/all-tests.nix
.
{
hostname = runTest ./hostname.nix;
}
Overrides can be added by defining an anonymous module in all-tests.nix
.
{
hostname = runTest {
imports = [ ./hostname.nix ];
defaults.networking.firewall.enable = false;
};
}
You can run a test with attribute name hostname
in nixos/tests/all-tests.nix
by invoking:
cd /my/git/clone/of/nixpkgs
nix-build -A nixosTests.hostname
Outside the nixpkgs
repository, you can instantiate the test by first importing the NixOS library,
let nixos-lib = import (nixpkgs + "/nixos/lib") { };
in
nixos-lib.runTest {
imports = [ ./test.nix ];
hostPkgs = pkgs; # the Nixpkgs package set used outside the VMs
defaults.services.foo.package = mypkg;
}
runTest
returns a derivation that runs the test.
There are a few special NixOS options for test VMs:
virtualisation.memorySize
The memory of the VM in megabytes.
virtualisation.vlans
The virtual networks to which the VM is connected. See
nat.nix
for an example.
virtualisation.writableStore
By default, the Nix store in the VM is not writable. If you enable this option, a writable union file system is mounted on top of the Nix store to make it appear writable. This is necessary for tests that run Nix operations that modify the store.
For more options, see the module
qemu-vm.nix
.
The test script is a sequence of Python statements that perform various
actions, such as starting VMs, executing commands in the VMs, and so on.
Each virtual machine is represented as an object stored in the variable
name
if this is also the identifier of the machine in the declarative
config. If you specified a node nodes.machine
, the following example starts the
machine, waits until it has finished booting, then executes a command
and checks that the output is more-or-less correct:
machine.start()
machine.wait_for_unit("default.target")
if not "Linux" in machine.succeed("uname"):
raise Exception("Wrong OS")
The first line is technically unnecessary; machines are implicitly started
when you first execute an action on them (such as wait_for_unit
or
succeed
). If you have multiple machines, you can speed up the test by
starting them in parallel:
start_all()
If the hostname of a node contains characters that can’t be used in a
Python variable name, those characters will be replaced with
underscores in the variable name, so nodes.machine-a
will be exposed
to Python as machine_a
.
The following methods are available on machine objects:
Simulate unplugging the Ethernet cable that connects the machine to the other machines. This happens by shutting down eth1 (the multicast interface used to talk to the other VMs). eth0 is kept online to still enable the test driver to communicate with the machine.
Allows you to directly interact with QEMU’s stdin, by forwarding
terminal input to the QEMU process.
This is for use with the interactive test driver, not for production
tests, which run unattended.
Output from QEMU is only read line-wise. Ctrl-c
kills QEMU and
Ctrl-d
closes console and returns to the test runner.
Copies a file from host to machine, e.g.,
copy_from_host("myfile", "/etc/my/important/file")
.
The first argument is the file on the host. Note that the “host” refers to the environment in which the test driver runs, which is typically the Nix build sandbox.
The second argument is the location of the file on the machine that will be written to.
The file is copied via the shared_dir
directory which is shared among
all the VMs (using a temporary directory).
The access rights bits will mimic the ones from the host file and
user:group will be root:root.
Copy a file from the host into the guest by piping it over the shell into the destination file. Works without host-guest shared folder. Prefer copy_from_host for whenever possible.
Copy a file from the VM (specified by an in-VM source path) to a path
relative to $out
. The file is copied via the shared_dir
shared among
all the VMs (using a temporary directory).
Simulate a sudden power failure, by telling the VM to exit immediately.
Debugging: Dump the contents of the TTY<n>
Execute a shell command, returning a list (status, stdout)
.
Commands are run with set -euo pipefail
set:
If several commands are separated by ;
and one fails, the
command as a whole will fail.
For pipelines, the last non-zero exit status will be returned (if there is one; otherwise zero will be returned).
Dereferencing unset variables fails the command.
It will wait for stdout to be closed.
If the command detaches, it must close stdout, as execute
will wait
for this to consume all output reliably. This can be achieved by
redirecting stdout to stderr >&2
, to /dev/console
, /dev/null
or
a file. Examples of detaching commands are sleep 365d &
, where the
shell forks a new process that can write to stdout and xclip -i
, where
the xclip
command itself forks without closing stdout.
Takes an optional parameter check_return
that defaults to True
.
Setting this parameter to False
will not check for the return code
and return -1 instead. This can be used for commands that shut down
the VM and would therefore break the pipe that would be used for
retrieving the return code.
A timeout for the command can be specified (in seconds) using the optional
timeout
parameter, e.g., execute(cmd, timeout=10)
or
execute(cmd, timeout=None)
. The default is 900 seconds.
Like succeed
, but raising an exception if the command returns a zero
status.
Forward a TCP port on the host to a TCP port on the guest. Useful during interactive testing.
Return a textual representation of what is currently visible on the machine’s screen using optical character recognition.
This requires enableOCR
to be set to true
.
Return a list of different interpretations of what is currently visible on the machine’s screen using optical character recognition. The number and order of the interpretations is not specified and is subject to change, but if no exception is raised at least one will be returned.
This requires enableOCR
to be set to true
.
Press Ctrl+Alt+Delete in the guest.
Prepares the machine to be reconnected which is useful if the
machine was started with allow_reboot = True
Take a picture of the display of the virtual machine, in PNG format. The screenshot will be available in the derivation output.
Simulate typing a sequence of characters on the virtual keyboard,
e.g., send_chars("foobar ")
will type the string foobar
followed by the Enter key.
Send keys to the kernel console. This allows interaction with the systemd
emergency mode, for example. Takes a string that is sent, e.g.,
send_console("\n\nsystemctl default\n")
.
Simulate pressing keys on the virtual keyboard, e.g.,
send_key("ctrl-alt-delete")
.
Please also refer to the QEMU documentation for more information on the input syntax: https://en.wikibooks.org/wiki/QEMU/Monitor#sendkey_keys
Send a command to the QEMU monitor. This allows attaching virtual USB disks to a running machine, among other things.
Allows you to directly interact with the guest shell. This should
only be used during test development, not in production tests.
Killing the interactive session with Ctrl-d
or Ctrl-c
also ends
the guest session.
Shut down the machine, waiting for the VM to exit.
Start the virtual machine. This method is asynchronous — it does not wait for the machine to finish booting.
Execute a shell command, raising an exception if the exit status is
not zero, otherwise returning the standard output. Similar to execute
,
except that the timeout is None
by default. See execute
for details on
command execution.
Transition from stage 1 to stage 2. This requires the
machine to be configured with testing.initrdBackdoor = true
and boot.initrd.systemd.enable = true
.
Runs systemctl
commands with optional support for
systemctl --user
# run `systemctl list-jobs --no-pager`
machine.systemctl("list-jobs --no-pager")
# spawn a shell for `any-user` and run
# `systemctl --user list-jobs --no-pager`
machine.systemctl("list-jobs --no-pager", "any-user")
Undo the effect of block
.
Wait until nobody is listening on the given TCP port and IP address
(default localhost
).
Wait until the supplied regular expressions match a line of the serial console output. This method is useful when OCR is not possible or inaccurate.
Waits until the file exists in the machine’s file system.
Wait until a process is listening on the given TCP port and IP address
(default localhost
).
Wait until a process is listening on the given UNIX-domain socket (default to a UNIX-domain stream socket).
Wait for a QMP event which you can filter with the event_filter
function.
The function takes as an input a dictionary of the event and if it returns True, we return that event,
if it does not, we wait for the next event and retry.
It will skip all events received in the meantime, if you want to keep them, you have to do the bookkeeping yourself and store them somewhere.
By default, it will wait up to 10 minutes, timeout
is in seconds.
Wait until the supplied regular expressions matches the textual
contents of the screen by using optical character recognition (see
get_screen_text
and get_screen_text_variants
).
This requires enableOCR
to be set to true
.
Wait for a systemd unit to get into “active” state. Throws exceptions on “failed” and “inactive” states as well as after timing out.
Wait until an X11 window has appeared whose name matches the given
regular expression, e.g., wait_for_window("Terminal")
.
Wait until it is possible to connect to the X server.
Like wait_until_succeeds
, but repeating the command until it fails.
Repeat a shell command with 1-second intervals until it succeeds.
Has a default timeout of 900 seconds which can be modified, e.g.
wait_until_succeeds(cmd, timeout=10)
. See execute
for details on
command execution.
Throws an exception on timeout.
Wait until the visible output on the chosen TTY matches regular expression. Throws an exception on timeout.
To test user units declared by systemd.user.services
the optional
user
argument can be used:
machine.start()
machine.wait_for_x()
machine.wait_for_unit("xautolock.service", "x-session-user")
This applies to systemctl
, get_unit_info
, wait_for_unit
,
start_job
and stop_job
.
For faster dev cycles it’s also possible to disable the code-linters (this shouldn’t be committed though):
{
skipLint = true;
nodes.machine =
{ config, pkgs, ... }:
{ # configuration…
};
testScript =
''
Python code…
'';
}
This will produce a Nix warning at evaluation time. To fully disable the linter, wrap the test script in comment directives to disable the Black linter directly (again, don’t commit this within the Nixpkgs repository):
{
testScript =
''
# fmt: off
Python code…
# fmt: on
'';
}
Similarly, the type checking of test scripts can be disabled in the following way:
{
skipTypeCheck = true;
nodes.machine =
{ config, pkgs, ... }:
{ # configuration…
};
}
To fail tests early when certain invariants are no longer met (instead of waiting for the build to time out), the decorator polling_condition
is provided. For example, if we are testing a program foo
that should not quit after being started, we might write the following:
@polling_condition
def foo_running():
machine.succeed("pgrep -x foo")
machine.succeed("foo --start")
machine.wait_until_succeeds("pgrep -x foo")
with foo_running:
... # Put `foo` through its paces
polling_condition
takes the following (optional) arguments:
seconds_interval
specifies how often the condition should be polled:
@polling_condition(seconds_interval=10)
def foo_running():
machine.succeed("pgrep -x foo")
description
is used in the log when the condition is checked. If this is not provided, the description is pulled from the docstring of the function. These two are therefore equivalent:
@polling_condition
def foo_running():
"check that foo is running"
machine.succeed("pgrep -x foo")
@polling_condition(description="check that foo is running")
def foo_running():
machine.succeed("pgrep -x foo")
When additional Python libraries are required in the test script, they can be
added using the parameter extraPythonPackages
. For example, you could add
numpy
like this:
{
extraPythonPackages = p: [ p.numpy ];
nodes = { };
# Type checking on extra packages doesn't work yet
skipTypeCheck = true;
testScript = ''
import numpy as np
assert str(np.zeros(4)) == "[0. 0. 0. 0.]"
'';
}
In that case, numpy
is chosen from the generic python3Packages
.
The following options can be used when writing tests.
enableOCR
Whether to enable Optical Character Recognition functionality for
testing graphical programs. See Machine objects
.
Type: boolean
Default:
false
Declared by:
nixos/lib/testing/driver.nix
|
defaults
NixOS configuration that is applied to all nodes
.
Type: module
Default:
{ }
Declared by:
nixos/lib/testing/nodes.nix
|
driver
Package containing a script that runs the test.
Type: package
Default: set by the test framework
Declared by:
nixos/lib/testing/driver.nix
|
extraBaseModules
NixOS configuration that, like defaults
, is applied to all nodes
and can not be undone with specialisation.<name>.inheritParentConfig
.
Type: module
Default:
{ }
Declared by:
nixos/lib/testing/nodes.nix
|
extraDriverArgs
Extra arguments to pass to the test driver.
They become part of driver
via wrapProgram
.
Type: list of string
Default:
[ ]
Declared by:
nixos/lib/testing/driver.nix
|
extraPythonPackages
Python packages to add to the test driver.
The argument is a Python package set, similar to pkgs.pythonPackages
.
Type: function that evaluates to a(n) list of package
Default:
<function>
Example:
p: [ p.numpy ]
Declared by:
nixos/lib/testing/driver.nix
|
globalTimeout
A global timeout for the complete test, expressed in seconds. Beyond that timeout, every resource will be killed and released and the test will fail.
By default, we use a 1 hour timeout.
Type: signed integer
Default:
3600
Example:
600
Declared by:
nixos/lib/testing/driver.nix
|
hostPkgs
Nixpkgs attrset used outside the nodes.
Type: raw value
Example:
import nixpkgs { inherit system config overlays; }
Declared by:
nixos/lib/testing/driver.nix
|
interactive
Tests can be run interactively
using the program in the test derivation’s .driverInteractive
attribute.
When they are, the configuration will include anything set in this submodule.
You can set any top-level test option here.
Example test module:
{ config, lib, ... }: {
nodes.rabbitmq = {
services.rabbitmq.enable = true;
};
# When running interactively ...
interactive.nodes.rabbitmq = {
# ... enable the web ui.
services.rabbitmq.managementPlugin.enable = true;
};
}
For details, see the section about running tests interactively.
Type: submodule
Declared by:
nixos/lib/testing/interactive.nix
|
meta
The meta
attributes that will be set on the returned derivations.
Not all meta
attributes are supported, but more can be added as desired.
Type: submodule
Default:
{ }
Declared by:
nixos/lib/testing/meta.nix
|
meta.broken
Sets the meta.broken
attribute on the test
derivation.
Type: boolean
Default:
false
Declared by:
nixos/lib/testing/meta.nix
|
meta.maintainers
The list of maintainers for this test.
Type: list of raw value
Default:
[ ]
Declared by:
nixos/lib/testing/meta.nix
|
meta.platforms
Sets the meta.platforms
attribute on the test
derivation.
Type: list of raw value
Default:
[
"aarch64-linux"
"armv5tel-linux"
"armv6l-linux"
"armv7a-linux"
"armv7l-linux"
"i686-linux"
"loongarch64-linux"
"m68k-linux"
"microblaze-linux"
"microblazeel-linux"
"mips-linux"
"mips64-linux"
"mips64el-linux"
"mipsel-linux"
"powerpc64-linux"
"powerpc64le-linux"
"riscv32-linux"
"riscv64-linux"
"s390-linux"
"s390x-linux"
"x86_64-linux"
"x86_64-darwin"
"i686-darwin"
"aarch64-darwin"
"armv7a-darwin"
]
Declared by:
nixos/lib/testing/meta.nix
|
meta.timeout
The test
’s meta.timeout
in seconds.
Type: null or signed integer
Default:
3600
Declared by:
nixos/lib/testing/meta.nix
|
name
The name of the test.
This is used in the derivation names of the driver
and test
runner.
Type: string
Declared by:
nixos/lib/testing/name.nix
|
node.pkgs
The Nixpkgs to use for the nodes.
Setting this will make the nixpkgs.*
options read-only, to avoid mistakenly testing with a Nixpkgs configuration that diverges from regular use.
Type: null or Nixpkgs package set
Default:
null
, so construct pkgs
according to the nixpkgs.*
options as usual.
Declared by:
nixos/lib/testing/nodes.nix
|
node.pkgsReadOnly
Whether to make the nixpkgs.*
options read-only. This is only relevant when node.pkgs
is set.
Set this to false
when any of the nodes
needs to configure any of the nixpkgs.*
options. This will slow down evaluation of your test a bit.
Type: boolean
Default:
node.pkgs != null
Declared by:
nixos/lib/testing/nodes.nix
|
node.specialArgs
An attribute set of arbitrary values that will be made available as module arguments during the resolution of module imports
.
Note that it is not possible to override these from within the NixOS configurations. If you argument is not relevant to imports
, consider setting defaults._module.args.<name>
instead.
Type: lazy attribute set of raw value
Default:
{ }
Declared by:
nixos/lib/testing/nodes.nix
|
nodes
An attribute set of NixOS configuration modules.
The configurations are augmented by the defaults
option.
They are assigned network addresses according to the nixos/lib/testing/network.nix
module.
A few special options are available, that aren’t in a plain NixOS configuration. See Configuring the nodes
Type: lazy attribute set of module
Declared by:
nixos/lib/testing/nodes.nix
|
passthru
Attributes to add to the returned derivations, which are not necessarily part of the build.
This is a bit like doing drv // { myAttr = true; }
(which would be lost by overrideAttrs
).
It does not change the actual derivation, but adds the attribute nonetheless, so that
consumers of what would be drv
have more information.
Type: lazy attribute set of raw value
Declared by:
nixos/lib/testing/run.nix
|
qemu.package
Which qemu package to use for the virtualisation of nodes
.
Type: package
Default:
"hostPkgs.qemu_test"
Declared by:
nixos/lib/testing/driver.nix
|
skipLint
Do not run the linters. This may speed up your iteration cycle, but it is not something you should commit.
Type: boolean
Default:
false
Declared by:
nixos/lib/testing/driver.nix
|
skipTypeCheck
Disable type checking. This must not be enabled for new NixOS tests.
This may speed up your iteration cycle, unless you’re working on the testScript
.
Type: boolean
Default:
false
Declared by:
nixos/lib/testing/driver.nix
|
test
Derivation that runs the test as its “build” process.
This implies that NixOS tests run isolated from the network, making them more dependable.
Type: package
Declared by:
nixos/lib/testing/run.nix
|
testScript
A series of python declarations and statements that you write to perform the test.
Type: string or function that evaluates to a(n) string
Declared by:
nixos/lib/testing/testScript.nix
|
You can run tests using nix-build
. For example, to run the test
login.nix
,
you do:
$ cd /my/git/clone/of/nixpkgs
$ nix-build -A nixosTests.login
After building/downloading all required dependencies, this will perform a build that starts a QEMU/KVM virtual machine containing a NixOS system. The virtual machine mounts the Nix store of the host; this makes VM creation very fast, as no disk image needs to be created. Afterwards, you can view a log of the test:
$ nix-store --read-log result
NixOS tests require virtualization support.
This means that the machine must have kvm
in its system features list, or apple-virt
in case of macOS.
These features are autodetected locally, but apple-virt
is only autodetected since Nix 2.19.0.
Features of remote builders must additionally be configured manually on the client, e.g. on NixOS with nix.buildMachines.*.supportedFeatures
or through general Nix configuration.
If you run the tests on a macOS machine, you also need a “remote” builder for Linux; possibly a VM. nix-darwin users may enable nix.linux-builder.enable
to launch such a VM.
The test itself can be run interactively. This is particularly useful when developing or debugging a test:
$ nix-build . -A nixosTests.login.driverInteractive
$ ./result/bin/nixos-test-driver
[...]
>>>
You can then take any Python statement, e.g.
>>> start_all()
>>> test_script()
>>> machine.succeed("touch /tmp/foo")
>>> print(machine.succeed("pwd")) # Show stdout of command
The function test_script
executes the entire test script and drops you
back into the test driver command line upon its completion. This allows
you to inspect the state of the VMs after the test (e.g. to debug the
test script).
The function <yourmachine>.shell_interact()
grants access to a shell running
inside a virtual machine. To use it, replace <yourmachine>
with the name of a
virtual machine defined in the test, for example: machine.shell_interact()
.
Keep in mind that this shell may not display everything correctly as it is
running within an interactive Python REPL, and logging output from the virtual
machine may overwrite input and output from the guest shell:
>>> machine.shell_interact()
machine: Terminal is ready (there is no initial prompt):
$ hostname
machine
As an alternative, you can proxy the guest shell to a local TCP server by first starting a TCP server in a terminal using the command:
$ socat 'READLINE,PROMPT=$ ' tcp-listen:4444,reuseaddr`
In the terminal where the test driver is running, connect to this server by using:
>>> machine.shell_interact("tcp:127.0.0.1:4444")
Once the connection is established, you can enter commands in the socat terminal where socat is running.
If your test has only a single VM, you may use e.g.
$ QEMU_NET_OPTS="hostfwd=tcp:127.0.0.1:2222-:22" ./result/bin/nixos-test-driver
to port-forward a port in the VM (here 22
) to the host machine (here port 2222
).
This naturally does not work when multiple machines are involved, since a single port on the host cannot forward to multiple VMs.
If the test defines multiple machines, you may opt to temporarily set
virtualisation.forwardPorts
in the test definition for debugging.
Such port forwardings connect via the VM’s virtual network interface.
Thus they cannot connect to ports that are only bound to the VM’s
loopback interface (127.0.0.1
), and the VM’s NixOS firewall
must be configured to allow these connections.
You can re-use the VM states coming from a previous run by setting the
--keep-vm-state
flag.
$ ./result/bin/nixos-test-driver --keep-vm-state
The machine state is stored in the $TMPDIR/vm-state-machinename
directory.
The .driverInteractive
attribute combines the regular test configuration with
definitions from the interactive
submodule. This gives you
a more usable, graphical, but slightly different configuration.
You can add your own interactive-only test configuration by adding extra
configuration to the interactive
submodule.
To interactively run only the regular configuration, build the <test>.driver
attribute
instead, and call it with the flag result/bin/nixos-test-driver --interactive
.
You can link NixOS module tests to the packages that they exercised, so that the tests can be run automatically during code review when the package gets changed. This is described in the nixpkgs manual.
Table of Contents
The NixOS test framework is a project of its own.
It consists of roughly the following components:
nixos/lib/test-driver
: The Python framework that sets up the test and runs the testScript
nixos/lib/testing
: The Nix code responsible for the wiring, written using the (NixOS) Module System.
These components are exposed publicly through:
nixos/lib/default.nix
: The public interface that exposes the nixos/lib/testing
entrypoint.
flake.nix
: Exposes the lib.nixos
, including the public test interface.
Beyond the test driver itself, its integration into NixOS and Nixpkgs is important.
pkgs/top-level/all-packages.nix
: Defines the nixosTests
attribute, used
by the package tests
attributes and OfBorg.
nixos/release.nix
: Defines the tests
attribute built by Hydra, independently, but analogous to nixosTests
nixos/release-combined.nix
: Defines which tests are channel blockers.
Finally, we have legacy entrypoints that users should move away from, but are cared for on a best effort basis.
These include pkgs.nixosTest
, testing-python.nix
and make-test-python.nix
.
We currently have limited unit tests for the framework itself. You may run these with nix-build -A nixosTests.nixos-test-driver
.
When making significant changes to the test framework, we run the tests on Hydra, to avoid disrupting the larger NixOS project.
For this, we use the python-test-refactoring
branch in the NixOS/nixpkgs
repository, and its corresponding Hydra jobset.
This branch is used as a pointer, and not as a feature branch.
Rebase the PR onto a recent, good evaluation of nixos-unstable
Create a baseline evaluation by force-pushing this revision of nixos-unstable
to python-test-refactoring
.
Note the evaluation number (we’ll call it <previous>
)
Push the PR to python-test-refactoring
and evaluate the PR on Hydra
Create a comparison URL by navigating to the latest build of the PR and adding to the URL ?compare=<previous>
. This is not necessary for the evaluation that comes right after the baseline.
Review the removed tests and newly failed tests using the constructed URL; otherwise you will accidentally compare iterations of the PR instead of changes to the PR base.
As we currently have some flaky tests, newly failing tests are expected, but should be reviewed to make sure that
The number of failures did not increase significantly.
All failures that do occur can reasonably be assumed to fail for a different reason than the changes.
Building, burning, and booting from an installation CD is rather tedious, so here is a quick way to see if the installer works properly:
# mount -t tmpfs none /mnt
# nixos-generate-config --root /mnt
$ nix-build '<nixpkgs/nixos>' -A config.system.build.nixos-install
# ./result/bin/nixos-install
To start a login shell in the new NixOS installation in /mnt
:
$ nix-build '<nixpkgs/nixos>' -A config.system.build.nixos-enter
# ./result/bin/nixos-enter
Table of Contents
The sources of the NixOS manual are in the nixos/doc/manual subdirectory of the Nixpkgs repository. This manual uses the Nixpkgs manual syntax.
You can quickly check your edits with the following:
$ cd /path/to/nixpkgs
$ $EDITOR doc/nixos/manual/... # edit the manual
$ nix-build nixos/release.nix -A manual.x86_64-linux
If the build succeeds, the manual will be in ./result/share/doc/nixos/index.html
.
There’s also a convenient development daemon.
The above instructions don’t deal with the appendix of available configuration.nix
options, and the manual pages related to NixOS. These are built, and written in a different location and in a different format, as explained in the next sections.
configuration.nix
options documentation The documentation for all the different configuration.nix
options is automatically generated by reading the description
s of all the NixOS options defined at nixos/modules/
. If you want to improve such description
, find it in the nixos/modules/
directory, and edit it and open a pull request.
To see how your changes render on the web, run again:
$ nix-build nixos/release.nix -A manual.x86_64-linux
And you’ll see the changes to the appendix in the path result/share/doc/nixos/options.html
.
You can also build only the configuration.nix(5)
manual page, via:
$ cd /path/to/nixpkgs
$ nix-build nixos/release.nix -A nixos-configuration-reference-manpage.x86_64-linux
And observe the result via:
$ man --local-file result/share/man/man5/configuration.nix.5
If you’re on a different architecture that’s supported by NixOS (check file nixos/release.nix
on Nixpkgs’ repository) then replace x86_64-linux
with the architecture. nix-build
will complain otherwise, but should also tell you which architecture you have + the supported ones.
nixos-*
tools’ manpages The manual pages for the tools available in the installation image can be found in Nixpkgs by running (e.g for nixos-rebuild
):
$ git ls | grep nixos-rebuild.8
Man pages are written in mdoc(7)
format and should be portable between mandoc and groff for rendering (except for minor differences, notably different spacing rules.)
For a preview, run man --local-file path/to/file.8
.
Being written in mdoc
, these manpages use semantic markup. This following subsections provides a guideline on where to apply which semantic elements.
In any manpage, commands, flags and arguments to the current executable should be marked according to their semantics. Commands, flags and arguments passed to other executables should not be marked like this and should instead be considered as code examples and marked with Ql
.
Use Fl
to mark flag arguments, Ar
for their arguments.
Repeating arguments should be marked by adding an ellipsis (spelled with periods, ...
).
Use Cm
to mark literal string arguments, e.g. the boot
command argument passed to nixos-rebuild
.
Optional flags or arguments should be marked with Op
. This includes optional repeating arguments.
Required flags or arguments should not be marked.
Mutually exclusive groups of arguments should be enclosed in curly brackets, preferably created with Bro
/Brc
blocks.
When an argument is used in an example it should be marked up with Ar
again to differentiate it from a constant. For example, a command with a --host name
option that calls ssh to retrieve the host’s local time would signify this thusly:
This will run
.Ic ssh Ar name Ic time
to retrieve the remote time.
Constant paths should be marked with Pa
, NixOS options with Va
, and environment variables with Ev
.
Generated paths, e.g. result/bin/run-hostname-vm
(where hostname
is a variable or arguments) should be marked as Ql
inline literals with their variable components marked appropriately.
When hostname
refers to an argument, it becomes .Ql result/bin/run- Ns Ar hostname Ns -vm
When hostname
refers to a variable, it becomes .Ql result/bin/run- Ns Va hostname Ns -vm
In free text names and complete invocations of other commands (e.g. ssh
or tar -xvf src.tar
) should be marked with Ic
, fragments of command lines should be marked with Ql
.
Larger code blocks or those that cannot be shown inline should use indented literal display block markup for their contents, i.e.
.Bd -literal -offset indent
...
.Ed
Contents of code blocks may be marked up further, e.g. if they refer to arguments that will be substituted into them:
.Bd -literal -offset indent
{
config.networking.hostname = "\c
.Ar hostname Ns \c
";
}
.Ed