feat: rewrite tarball generation to use proper nixos-install + nixos-…

…enter

Supersedes #243.

.github/workflows/main.yml

@@ -66,15 +66,25 @@ jobs:
  echo ${{ needs.prepare.outputs.version }} > ./VERSION
  echo $(git rev-parse HEAD) >> ./VERSION
 
- - name: Build installer 🛠️
+ - name: Build tarballs 🛠️
+ # We can't just nix run here because nix is not on root's PATH in the container
  run: |
- nix build '.#nixosConfigurations.mysystem.config.system.build.installer'
+ nix build .#nixosConfigurations.modern.config.system.build.tarballBuilder
+ sudo ./result nixos-wsl.tar.gz
+ nix build .#nixosConfigurations.legacy.config.system.build.tarballBuilder
+ sudo ./result nixos-wsl-legacy.tar.gz
 
- - name: Upload installer 📤
+ - name: Upload tarball 📤
  uses: actions/upload-artifact@v3
  with:
- name: installer
- path: result/tarball/nixos-wsl-installer.tar.gz
+ name: tarball
+ path: nixos-wsl.tar.gz
+
+ - name: Upload legacy tarball 📤
+ uses: actions/upload-artifact@v3
+ with:
+ name: tarball-legacy
+ path: nixos-wsl-legacy.tar.gz
 
  checks:
  name: Flake Check 📋
@@ -117,10 +127,10 @@ jobs:
  - name: Checkout
  uses: actions/checkout@v4
 
- - name: Download installer 📥
+ - name: Download tarball 📥
  uses: actions/download-artifact@v3
  with:
- name: installer
+ name: tarball-legacy
 
  - name: Execute test 🧪
  shell: pwsh

.github/workflows/release.yml

@@ -14,13 +14,12 @@ jobs:
  name: Create Release 📢
  runs-on: ubuntu-latest
  steps:
- - name: Download installer 📥
+ - name: Download tarball 📥
  uses: actions/download-artifact@v3
- with:
- name: installer
 
  - name: Generate checksums 🔑
  run: |
+ mv */*.tar.gz .
  for x in *.tar.gz; do
  sha256sum $x > ${x}.sha256
  done
@@ -29,7 +28,9 @@ jobs:
  uses: softprops/action-gh-release@v1
  with:
  files: |
- nixos-wsl-installer.tar.gz
- nixos-wsl-installer.tar.gz.sha256
+ nixos-wsl.tar.gz
+ nixos-wsl.tar.gz.sha256
+ nixos-wsl-legacy.tar.gz
+ nixos-wsl-legacy.tar.gz.sha256
  env:
  GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}

.gitignore

@@ -1,3 +1,3 @@
 result
 result-*
-nixos-wsl-installer.tar.gz
+nixos-wsl*.tar.gz

README.md

@@ -9,18 +9,23 @@ A minimal root filesystem for running NixOS on WSL. It can be used with
 [DistroLauncher](https://github.com/microsoft/WSL-DistroLauncher) as
 `install.tar.gz` or as input to `wsl --import --version 2`.
 
+## System requirements
+
+NixOS-WSL is tested with the Windows Store version of WSL 2, which is now available on all supported Windows releases (both 10 and 11).
+Support for older "inbox" versions is best-effort.
+
 ## Quick start
 
-First, [download the latest release\'s installer](https://github.com/nix-community/NixOS-WSL/releases/latest).
+First, [download the latest release](https://github.com/nix-community/NixOS-WSL/releases/latest).
 
 Then open up a Terminal, PowerShell or Command Prompt and run:
 
 ```sh
-wsl --import NixOS .\NixOS\ nixos-wsl-installer.tar.gz --version 2
+wsl --import NixOS .\NixOS\ nixos-wsl.tar.gz --version 2
 ```
 
 This sets up a new WSL distribution `NixOS` that is installed under
-`.\NixOS`. `nixos-wsl-installer.tar.gz` is the path to the file you
+`.\NixOS`. `nixos-wsl.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:
@@ -29,11 +34,6 @@ You can now run NixOS:
 wsl -d NixOS
 ```
 
-The installer will unpack the file system and subsequently start NixOS.
-A few warnings about file systems and locales will pop up. You can
-safely ignore them. After systemd has started, you should be greeted
-with a bash prompt inside your fresh NixOS installation.
-
 If you want to make NixOS your default distribution, you can do so with
 
 ```sh
@@ -68,57 +68,34 @@ If you have a flakes-enabled Nix, you can use the following command to
 build your own tarball instead of relying on a prebuilt one:
 
 ```cmd
-nix build github:nix-community/NixOS-WSL#nixosConfigurations.mysystem.config.system.build.installer
+sudo nix run github:nix-community/NixOS-WSL#nixosConfigurations.modern.config.system.build.tarballBuilder
 ```
 
 Or, if you want to build with local changes, run inside your checkout:
 
 ```cmd
-nix build .#nixosConfigurations.mysystem.config.system.build.installer
+sudo nix run .#nixosConfigurations.your-hostname.config.system.build.tarballBuilder
 ```
 
 Without a flakes-enabled Nix, you can build a tarball using:
 
 ```cmd
-nix-build -A nixosConfigurations.mysystem.config.system.build.installer
-```
+nix-build -A nixosConfigurations.mysystem.config.system.build.tarballBuilder && sudo ./result/bin/nixos-wsl-tarball-builder
 
-The resulting installer tarball can then be found under
-`./result/tarball/nixos-wsl-installer.tar.gz`.
+```
 
-You can also build a rootfs tarball without wrapping it in the installer
-by replacing `installer` with `tarball` in the above commands. The
-rootfs tarball can then be found under
-`./result/tarball/nixos-wsl-x86_64-linux.tar.gz`.
+The resulting tarball can then be found under `nixos-wsl.tar.gz`.
 
 ## Design
 
 Getting NixOS to run under WSL requires some workarounds:
 
-### 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.
-
-### Installer
-
-Usually WSL distributions ship as a tarball of their root file system.
-These tarballs however, can not contain any hard-links due to the way
-they are unpacked by WSL, resulting in an \"Unspecified Error\". By
-default some Nix-derivations will contain hard-links when they are
-built. This results in system tarballs that can not be imported into
-WSL. To circumvent this problem, the rootfs tarball is wrapped in that
-of a minimal distribution (the installer), that is packaged without any
-hard-links. When the installer system is started for the first time, it
-overwrites itself with the contents of the rootfs tarball.
+- instead of directly loading systemd, we use a small shim that runs the NixOS activation scripts first
+- some additional binaries required by WSL's internal tooling are symlinked to FHS paths on activation
+
+Running on older WSL versions also requires a workaround to spawn systemd by hijacking the root shell and
+spawning a container with systemd inside. This method of running things is deprecated and not recommended,
+however still available as `nixos-wsl-legacy.tar.gz` or via `wsl.nativeSystemd = false`.
 
 ## License
 

checks/username.nix

@@ -6,9 +6,9 @@
 
 let
  baseModule = { ... }: {
- imports = [ ../configuration.nix ];
-
+ imports = [ ../modules ];
  wsl.enable = true;
+ wsl.defaultUser = "nixos";
  };
  changedUsername = { lib, ... }: {
  wsl.defaultUser = lib.mkForce "different";

flake.nix

@@ -26,11 +26,25 @@
  };
  nixosModules.default = self.nixosModules.wsl;
 
- nixosConfigurations.mysystem = nixpkgs.lib.nixosSystem {
- system = "x86_64-linux";
- modules = [
- ./configuration.nix
- ];
+ nixosConfigurations = {
+ modern = nixpkgs.lib.nixosSystem {
+ system = "x86_64-linux";
+ modules = [
+ self.nixosModules.default
+ { wsl.enable = true; }
+ ];
+ };
+
+ legacy = nixpkgs.lib.nixosSystem {
+ system = "x86_64-linux";
+ modules = [
+ self.nixosModules.default
+ {
+ wsl.enable = true;
+ wsl.nativeSystemd = false;
+ }
+ ];
+ };
  };
 
  } //