feat: native systemd support (#134)

3 files changed, 154 insertions, 123 deletions

diff --git a/modules/installer.nix b/modules/installer.nix
index 45d191a..3fd404f 100644
--- a/modules/installer.nix
+++ b/modules/installer.nix
@@ -48,9 +48,7 @@ with builtins; with lib; {
         compressionExtension = ".gz";
         extraArgs = "--hard-dereference";
 
-        storeContents = with pkgs; pkgs2storeContents [
-          installer
-        ];
+        storeContents = pkgs2storeContents [ installer ];
 
         contents = [
           { source = config.environment.etc."wsl.conf".source; target = "/etc/wsl.conf"; }
diff --git a/modules/interop.nix b/modules/interop.nix
index b7babfb..d055d4b 100644
--- a/modules/interop.nix
+++ b/modules/interop.nix
@@ -74,9 +74,6 @@ with builtins; with lib;
           };
       };
 
-      # Include Windows %PATH% in Linux $PATH.
-      environment.extraInit = mkIf cfg.includePath ''PATH="$PATH:$WSLPATH"'';
-
       warnings =
         let
           registrations = config.boot.binfmt.registrations;
diff --git a/modules/wsl-distro.nix b/modules/wsl-distro.nix
index 9b187d1..ded84a3 100644
--- a/modules/wsl-distro.nix
+++ b/modules/wsl-distro.nix
@@ -2,144 +2,180 @@
 
 with builtins; with lib;
 {
-  options.wsl = with types;
-    let
-      coercedToStr = coercedTo (oneOf [ bool path int ]) (toString) str;
-    in
-    {
-      enable = mkEnableOption "support for running NixOS as a WSL distribution";
-      automountPath = mkOption {
-        type = str;
-        default = "/mnt";
-        description = "The path where windows drives are mounted (e.g. /mnt/c)";
-      };
-      automountOptions = mkOption {
-        type = str;
-        default = "metadata,uid=1000,gid=100";
-        description = "Options to use when mounting windows drives";
-      };
-      defaultUser = mkOption {
-        type = str;
-        default = "nixos";
-        description = "The name of the default user";
-      };
-      startMenuLaunchers = mkEnableOption "shortcuts for GUI applications in the windows start menu";
-      wslConf = mkOption {
-        type = attrsOf (attrsOf (oneOf [ string int bool ]));
-        description = "Entries that are added to /etc/wsl.conf";
-      };
+  options.wsl = with types; {
+    enable = mkEnableOption "support for running NixOS as a WSL distribution";
+    nativeSystemd = mkOption {
+      type = bool;
+      default = false;
+      description = "Use native WSL systemd support";
+    };
+    automountPath = mkOption {
+      type = str;
+      default = "/mnt";
+      description = "The path where windows drives are mounted (e.g. /mnt/c)";
+    };
+    automountOptions = mkOption {
+      type = str;
+      default = "metadata,uid=1000,gid=100";
+      description = "Options to use when mounting windows drives";
+    };
+    defaultUser = mkOption {
+      type = str;
+      default = "nixos";
+      description = "The name of the default user";
+    };
+    startMenuLaunchers = mkEnableOption "shortcuts for GUI applications in the windows start menu";
+    wslConf = mkOption {
+      type = attrsOf (attrsOf (oneOf [ string int bool ]));
+      description = "Entries that are added to /etc/wsl.conf";
     };
+  };
 
   config =
     let
       cfg = config.wsl;
       syschdemd = pkgs.callPackage ../scripts/syschdemd.nix { inherit (cfg) automountPath defaultUser; };
+      shim = pkgs.callPackage ../scripts/native-systemd-shim/shim.nix { };
+
+      bashWrapper = pkgs.runCommand "nixos-wsl-bash-wrapper" { nativeBuildInputs = [ pkgs.makeWrapper ]; } ''
+        makeWrapper ${pkgs.bashInteractive}/bin/sh $out/bin/sh --prefix PATH ':' ${lib.makeBinPath [pkgs.systemd pkgs.gnugrep]}
+      '';
+
+      bash = if cfg.nativeSystemd then bashWrapper else pkgs.bashInteractive;
     in
-    mkIf cfg.enable {
-
-      wsl.wslConf = {
-        automount = {
-          enabled = true;
-          mountFsTab = true;
-          root = "${cfg.automountPath}/";
-          options = cfg.automountOptions;
+    mkMerge [
+      (mkIf cfg.enable {
+        wsl.wslConf = {
+          automount = {
+            enabled = true;
+            mountFsTab = true;
+            root = "${cfg.automountPath}/";
+            options = cfg.automountOptions;
+          };
+          network = {
+            generateResolvConf = mkDefault true;
+            generateHosts = mkDefault true;
+          };
         };
-        network = {
-          generateResolvConf = mkDefault true;
-          generateHosts = mkDefault true;
-        };
-      };
-
-      # We don't need a boot loader
-      boot.loader.grub.enable = false;
-      system.build.installBootLoader = "${pkgs.coreutils}/bin/true";
-      boot.initrd.enable = false;
-      system.build.initialRamdisk = pkgs.runCommand "fake-initrd" { } ''
-        mkdir $out
-        touch $out/${config.system.boot.loader.initrdFile}
-      '';
-      system.build.initialRamdiskSecretAppender = pkgs.writeShellScriptBin "append-initrd-secrets" "";
 
-      hardware.opengl.enable = true; # Enable GPU acceleration
+        # We don't need a boot loader
+        boot.loader.grub.enable = false;
+        system.build.installBootLoader = "${pkgs.coreutils}/bin/true";
+        boot.initrd.enable = false;
+        system.build.initialRamdisk = pkgs.runCommand "fake-initrd" { } ''
+          mkdir $out
+          touch $out/${config.system.boot.loader.initrdFile}
+        '';
+        system.build.initialRamdiskSecretAppender = pkgs.writeShellScriptBin "append-initrd-secrets" "";
+
+        hardware.opengl.enable = true; # Enable GPU acceleration
 
-      environment = {
+        environment = {
 
-        etc = {
-          "wsl.conf".text = generators.toINI { } cfg.wslConf;
+          etc = {
+            "wsl.conf".text = generators.toINI { } cfg.wslConf;
 
-          # DNS settings are managed by WSL
-          hosts.enable = !config.wsl.wslConf.network.generateHosts;
-          "resolv.conf".enable = !config.wsl.wslConf.network.generateResolvConf;
-        };
+            # DNS settings are managed by WSL
+            hosts.enable = !config.wsl.wslConf.network.generateHosts;
+            "resolv.conf".enable = !config.wsl.wslConf.network.generateResolvConf;
+          };
 
-        systemPackages = [
-          (pkgs.runCommand "wslpath" { } ''
-            mkdir -p $out/bin
-            ln -s /init $out/bin/wslpath
-          '')
-        ];
-      };
+          systemPackages = [
+            (pkgs.runCommand "wslpath" { } ''
+              mkdir -p $out/bin
+              ln -s /init $out/bin/wslpath
+            '')
+          ];
+        };
 
-      networking.dhcpcd.enable = false;
+        networking.dhcpcd.enable = false;
 
-      users.users.${cfg.defaultUser} = {
-        isNormalUser = true;
-        uid = 1000;
-        extraGroups = [ "wheel" ]; # Allow the default user to use sudo
-      };
+        users.users.${cfg.defaultUser} = {
+          isNormalUser = true;
+          uid = 1000;
+          extraGroups = [ "wheel" ]; # Allow the default user to use sudo
+        };
 
-      users.users.root = {
-        shell = "${syschdemd}/bin/syschdemd";
         # Otherwise WSL fails to login as root with "initgroups failed 5"
-        extraGroups = [ "root" ];
-      };
+        users.users.root.extraGroups = [ "root" ];
+
+        security.sudo.wheelNeedsPassword = mkDefault false; # The default user will not have a password by default
+
+        system.activationScripts = {
+          copy-launchers = mkIf cfg.startMenuLaunchers (
+            stringAfter [ ] ''
+              for x in applications icons; do
+                echo "Copying /usr/share/$x"
+                mkdir -p /usr/share/$x
+                ${pkgs.rsync}/bin/rsync -ar --delete $systemConfig/sw/share/$x/. /usr/share/$x
+              done
+            ''
+          );
+          populateBin = stringAfter [ ] ''
+            echo "setting up /bin..."
+            ln -sf /init /bin/wslpath
+            ln -sf ${bash}/bin/sh /bin/sh
+            ln -sf ${pkgs.util-linux}/bin/mount /bin/mount
+          '';
+        };
+
+        systemd = {
+          # Disable systemd units that don't make sense on WSL
+          services = {
+            "serial-getty@ttyS0".enable = false;
+            "serial-getty@hvc0".enable = false;
+            "getty@tty1".enable = false;
+            "autovt@".enable = false;
+            firewall.enable = false;
+            systemd-resolved.enable = false;
+            systemd-udevd.enable = false;
+          };
+
+          tmpfiles.rules = [
+            # Don't remove the X11 socket
+            "d /tmp/.X11-unix 1777 root root"
+          ];
+
+          # Don't allow emergency mode, because we don't have a console.
+          enableEmergencyMode = false;
+        };
 
-      security.sudo = {
-        extraConfig = ''
+        warnings = (optional (config.systemd.services.systemd-resolved.enable && config.wsl.wslConf.network.generateResolvConf) "systemd-resolved is enabled, but resolv.conf is managed by WSL");
+      })
+      (mkIf (!cfg.nativeSystemd) {
+        users.users.root.shell = "${syschdemd}/bin/syschdemd";
+        security.sudo.extraConfig = ''
           Defaults env_keep+=INSIDE_NAMESPACE
         '';
-        wheelNeedsPassword = mkDefault false; # The default user will not have a password by default
-      };
-
-      system.activationScripts = {
-        copy-launchers = mkIf cfg.startMenuLaunchers (
-          stringAfter [ ] ''
-            for x in applications icons; do
-              echo "Copying /usr/share/$x"
-              mkdir -p /usr/share/$x
-              ${pkgs.rsync}/bin/rsync -ar --delete $systemConfig/sw/share/$x/. /usr/share/$x
-            done
-          ''
-        );
-        populateBin = stringAfter [ ] ''
-          echo "setting up /bin..."
-          ln -sf /init /bin/wslpath
-          ln -sf ${pkgs.bashInteractive}/bin/bash /bin/sh
-          ln -sf ${pkgs.util-linux}/bin/mount /bin/mount
-        '';
-      };
-
-      systemd = {
-        # Disable systemd units that don't make sense on WSL
-        services = {
-          "serial-getty@ttyS0".enable = false;
-          "serial-getty@hvc0".enable = false;
-          "getty@tty1".enable = false;
-          "autovt@".enable = false;
-          firewall.enable = false;
-          systemd-resolved.enable = false;
-          systemd-udevd.enable = false;
+        wsl.wslConf.users.default = "root";
+
+        # Include Windows %PATH% in Linux $PATH.
+        environment.extraInit = mkIf cfg.interop.includePath ''PATH="$PATH:$WSLPATH"'';
+      })
+      (mkIf cfg.nativeSystemd {
+        wsl.wslConf = {
+          user.default = cfg.defaultUser;
+          boot.systemd = true;
         };
 
-        tmpfiles.rules = [
-          # Don't remove the X11 socket
-          "d /tmp/.X11-unix 1777 root root"
-        ];
-
-        # Don't allow emergency mode, because we don't have a console.
-        enableEmergencyMode = false;
-      };
+        system.activationScripts = {
+          shimSystemd = stringAfter [ ] ''
+            echo "setting up /sbin/init shim..."
+            mkdir -p /sbin
+            ln -sf ${shim}/bin/nixos-wsl-native-systemd-shim /sbin/init
+          '';
+        };
 
-      warnings = (optional (config.systemd.services.systemd-resolved.enable && config.wsl.wslConf.network.generateResolvConf) "systemd-resolved is enabled, but resolv.conf is managed by WSL");
-    };
+        environment = {
+          # preserve $PATH from parent
+          variables.PATH = [ "$PATH" ];
+          extraInit = ''
+            export WSLPATH=$(echo "$PATH" | tr ':' '\n' | grep -E "^${cfg.automountPath}" | tr '\n' ':')
+            ${if cfg.interop.includePath then "" else ''
+              export PATH=$(echo "$PATH" | tr ':' '\n' | grep -vE "^${cfg.automountPath}" | tr '\n' ':')
+            ''}
+          '';
+        };
+      })
+    ];
 }