fix: default user name isn't necessarily the same as user attr name

checks/side-effects.nix

@@ -1,7 +1,7 @@
 # Test that including the WSL module in a config does not change anything without enabling it
 
-{ inputs
-, system
+{ system
+, inputs
 , emptyFile
 , ...
 }:

checks/username.nix

@@ -0,0 +1,29 @@
+{ system
+, inputs
+, runCommand
+, ...
+}:
+
+let
+  baseModule = { ... }: {
+    imports = [ ../configuration.nix ];
+
+    wsl.enable = true;
+  };
+  changedUsername = { lib, ... }: {
+    wsl.defaultUser = lib.mkForce "different";
+  };
+  changedUserAttr = { config, lib, ... }: {
+    wsl.defaultUser = lib.mkForce "userattr";
+    users.users.${config.wsl.defaultUser}.name = "username";
+  };
+  buildConfig = module: (inputs.nixpkgs.lib.nixosSystem {
+    inherit system;
+    modules = [ baseModule module ];
+  }).config.system.build.toplevel;
+in
+runCommand "different=usernames" { } ''
+  mkdir -p $out
+  ln -s ${buildConfig changedUsername} $out/changedUsername
+  ln -s ${buildConfig changedUserAttr} $out/changedUserAttr
+''

flake.nix

@@ -55,6 +55,7 @@
               nixpkgs-fmt = pkgs.callPackage ./checks/nixpkgs-fmt.nix args;
               shfmt = pkgs.callPackage ./checks/shfmt.nix args;
               side-effects = pkgs.callPackage ./checks/side-effects.nix args;
+              username = pkgs.callPackage ./checks/username.nix args;
             };
 
           packages.staticShim = pkgs.pkgsStatic.callPackage ./scripts/native-systemd-shim/shim.nix { };

modules/wsl-distro.nix

@@ -104,6 +104,9 @@ with lib; {
               ln -sf ${bash}/bin/sh /bin/sh
               ln -sf ${pkgs.util-linux}/bin/mount /bin/mount
             '';
+            update-entrypoint.text = ''
+              ln -sf ${config.users.users.root.shell} /nix/nixos-wsl/entrypoint
+            '';
           };
 
           systemd = {
@@ -153,7 +156,7 @@ with lib; {
         })
         (mkIf cfg.nativeSystemd {
           wsl.wslConf = {
-            user.default = cfg.defaultUser;
+            user.default = config.users.users.${cfg.defaultUser}.name;
             boot.systemd = true;
           };
 

tests/username-change/username-change.Tests.ps1

@@ -0,0 +1,19 @@
+BeforeAll {
+  . $PSScriptRoot/../lib/lib.ps1
+}
+
+Describe "Login Shell" {
+  BeforeAll {
+    $distro = Install-Distro
+  }
+
+  It "should be possible to change the username" {
+    $distro.Launch("whoami") | Select-Object -Last 1 | Should -BeExactly "nixos"
+    $distro.InstallConfig("$PSScriptRoot/username-change.nix")
+    $distro.Launch("whoami") | Select-Object -Last 1 | Should -BeExactly "different-name"
+  }
+
+  AfterAll {
+    $distro.Uninstall()
+  }
+}

tests/username-change/username-change.nix

@@ -0,0 +1,6 @@
+{ pkgs, lib, ... }:
+{
+  imports = [ ./base.nix ];
+
+  wsl.defaultUser = lib.mkForce "different-name";
+}