NixOS on WSL

A minimal root filesystem for running NixOS on WSL. It can be used with DistroLauncher as install.tar.gz or as input to wsl --import --version 2.

Quick start

First, download the latest release's system tarball.

Then open up a Terminal, PowerShell or Command Prompt and run:

wsl --import NixOS .\NixOS\ nixos-system-x86_64-linux.tar.gz --version 2

This sets up a new WSL distribution NixOS that is installed under .\NixOS. nixos-system-x86_64-linux.tar.gz is the path to the file you downloaded earlier. You might need to change this path or change to the download directory first.

You can now run NixOS:

wsl -d NixOS

You will be dropped into a very primitive sh shell. From here you need to run this once:

/nix/var/nix/profiles/system/activate

A few warnings about locales will pop up. You can safely ignore them.

Exit and restart WSL and you should be greeted with a much fancier bash prompt inside your fresh NixOS.

If you want to make NixOS your default distribution, you can do so via wsl -s NixOS.

systemd support

WSL comes with its own (non-substitutable) init system while NixOS uses systemd. Simply starting systemd later on does not work out of the box, because systemd as system instance refuses to start if it is not PID 1. This unfortunate combination is resolved in two ways:

• the user's default shell is replaced by a wrapper script that acts is init system and then drops to the actual shell
• systemd is started in its own PID namespace; therefore, it is PID 1. The shell wrapper (see above) enters the systemd namespace before dropping to the shell.

Build your own system tarball

This requires access to a system that already has Nix installed. Please refer to the Nix installation guide if that's not the case.

If you have a flakes-enabled Nix, you can use the following command to buld your own tarball instead of relying on a prebuilt one:

nix build github:Trundle/NixOS-WSL#nixosConfigurations.mysystem.config.system.build.tarball

Or, if you want to build with local changes, run inside your checkout:

nix build .#nixosConfigurations.mysystem.config.system.build.tarball

Without a flakes-enabled Nix, you can build a tarball using:

nix-build -A system -A config.system.build.tarball ./nixos.nix

The resulting mini rootfs can then be found under ./result-2/tarball/nixos-system-x86_64-linux.tar.gz.

License

Apache License, Version 2.0. See LICENSE or http://www.apache.org/licenses/LICENSE-2.0.html for details.

Further links

• DistroLauncher
• A quick way into a systemd "bottle" for WSL
• NixOS in Windows Store for Windows Subsystem for Linux
• wsl2-hacks