nixos/programs/gnome-session: add name option for session and components

Also updated the usage for `xToUnit` function from systemd-lib NixOS
library.

modules/nixos/programs/gnome-session/default.nix

@@ -10,7 +10,7 @@ let
 
   # The bulk of the work. Pretty much the main purpose of this module.
   sessionPackages = lib.mapAttrsToList
-    (name: session:
+    (_: session:
       let
         gnomeSession = ''
           [GNOME Session]
@@ -22,7 +22,7 @@ let
           [Desktop Entry]
           Name=@fullName@
           Comment=${session.description}
-          Exec="@out@/libexec/${name}-session"
+          Exec="@out@/libexec/${session.name}-session"
           Type=Application
           DesktopNames=${lib.concatStringsSep ";" session.desktopNames};
         '';
@@ -46,14 +46,14 @@ let
           {
             wayland = ''
               (
-                DISPLAY_SESSION_FILE="$out/share/wayland-sessions/${name}.desktop"
+                DISPLAY_SESSION_FILE="$out/share/wayland-sessions/${session.name}.desktop"
                 install -Dm0644 "$displaySessionPath" "$DISPLAY_SESSION_FILE"
                 ${hasMoreDisplays "Wayland"} substituteAllInPlace "$DISPLAY_SESSION_FILE"
               )
             '';
             x11 = ''
               (
-                DISPLAY_SESSION_FILE="$out/share/xsessions/${name}.desktop"
+                DISPLAY_SESSION_FILE="$out/share/xsessions/${session.name}.desktop"
                 install -Dm0644 "$displaySessionPath" "$DISPLAY_SESSION_FILE"
                 ${hasMoreDisplays "X11"} substituteAllInPlace "$DISPLAY_SESSION_FILE"
               )
@@ -66,13 +66,10 @@ let
           session.display;
 
         installDesktops =
-          let
-            sessionName = name;
-          in
           lib.mapAttrsToList
             (name: component:
               let
-                scriptName = "${sessionName}-${name}-script";
+                scriptName = "${session.name}-${component.name}-script";
 
                 # There's already a lot of bad bad things in this world, we
                 # don't to add more of it here (only a fraction of it, though).
@@ -90,21 +87,21 @@ let
               '')
             session.components;
       in
-      pkgs.runCommandLocal "${name}-desktop-session-files"
+      pkgs.runCommandLocal "${session.name}-desktop-session-files"
         {
           env = {
             inherit (session) fullName;
           };
           inherit displaySession gnomeSession sessionScript;
           passAsFile = [ "displaySession" "gnomeSession" "sessionScript" ];
-          passthru.providedSessions = [ name ];
+          passthru.providedSessions = [ session.name ];
         }
         ''
-          SESSION_SCRIPT="$out/libexec/${name}-session"
+          SESSION_SCRIPT="$out/libexec/${session.name}-session"
           install -Dm0755 "$sessionScriptPath" "$SESSION_SCRIPT"
           substituteAllInPlace "$SESSION_SCRIPT"
 
-          GNOME_SESSION_FILE="$out/share/gnome-session/sessions/${name}.session"
+          GNOME_SESSION_FILE="$out/share/gnome-session/sessions/${session.name}.session"
           install -Dm0644 "$gnomeSessionPath" "$GNOME_SESSION_FILE"
           substituteAllInPlace "$GNOME_SESSION_FILE"
 
@@ -116,26 +113,26 @@ let
     cfg.sessions;
 
   sessionSystemdUnits = lib.concatMapAttrs
-    (name: session:
+    (_: session:
       let
         inherit (utils.systemdUtils.lib)
           pathToUnit serviceToUnit targetToUnit timerToUnit socketToUnit;
 
         mkSystemdUnits = name: component: {
-          "${component.id}.service" = serviceToUnit component.id component.serviceUnit;
+          "${component.id}.service" = serviceToUnit component.serviceUnit;
-          "${component.id}.target" = targetToUnit component.id component.targetUnit;
+          "${component.id}.target" = targetToUnit component.targetUnit;
         } // lib.optionalAttrs (component.socketUnit != null) {
-          "${component.id}.socket" = socketToUnit component.id component.socketUnit;
+          "${component.id}.socket" = socketToUnit component.socketUnit;
         } // lib.optionalAttrs (component.timerUnit != null) {
-          "${component.id}.timer" = timerToUnit component.id component.timerUnit;
+          "${component.id}.timer" = timerToUnit component.timerUnit;
         } // lib.optionalAttrs (component.pathUnit != null) {
-          "${component.id}.path" = pathToUnit component.id component.pathUnit;
+          "${component.id}.path" = pathToUnit component.pathUnit;
         };
 
         componentsUnits = lib.concatMapAttrs mkSystemdUnits session.components;
       in
       componentsUnits // {
-        "gnome-session@${name}.target" = targetToUnit "gnome-session@${name}" session.targetUnit;
+        "gnome-session@${session.name}.target" = targetToUnit session.targetUnit;
       }
     )
     cfg.sessions;

modules/nixos/programs/gnome-session/submodules/component-type.nix

@@ -19,6 +19,13 @@ let
 in
 {
   options = {
+    name = lib.mkOption {
+      type = lib.types.nonEmptyStr;
+      description = "Component name.";
+      default = name;
+      example = "desktop-manager";
+    };
+
     description = lib.mkOption {
       type = lib.types.nonEmptyStr;
       description = "One-sentence description of the component.";
@@ -163,7 +170,7 @@ in
         The identifier of the component used in generating filenames for its
         `.desktop` files and as part of systemd unit names.
       '';
-      default = "${session.name}.${name}";
+      default = "${session.name}.${config.name}";
       defaultText = "\${session-name}.\${name}";
       readOnly = true;
     };
@@ -203,7 +210,7 @@ in
       * Even if we have a way to limit starting desktop components with
       `systemd-xdg-autostart-condition`, using `Service.ExecCondition=` would
       severely limit possible reuse of desktop components with other
-      NixOS-module-generated sessiond sessions so we're not bothering with
+      NixOS-module-generated gnome-session sessions so we're not bothering with
       those.
 
       TODO: Is `Type=notify` a good default?

modules/nixos/programs/gnome-session/submodules/session-type.nix

@@ -28,6 +28,22 @@ let
 in
 {
   options = {
+    name = lib.mkOption {
+      type = lib.types.nonEmptyStr;
+      description = ''
+        The identifier of the desktop environment to be used for the filenames
+        of related outputs.
+
+        ::: {.note}
+        While there is no formal specification around naming them, a common
+        convention is to use kebab-casing of the name (e.g., "mosey-branch" for
+        "Mosey Branch").
+        :::
+      '';
+      default = name;
+      example = "mosey-branch";
+    };
+
     fullName = lib.mkOption {
       type = lib.types.nonEmptyStr;
       description = "The display name of the desktop environment.";
@@ -188,19 +204,6 @@ in
         }
       '';
     };
-
-    sessionPackage = lib.mkOption {
-      type = lib.types.package;
-      description = ''
-        The collective package containing everything desktop-related
-        such as:
-
-        * The display session (`<name>.desktop`) files.
-        * gnome-session `.session` file.
-        * The components `.desktop` file.
-      '';
-      readOnly = true;
-    };
   };
 
   config = {