nixos/packagekit: RFC42 support and drop pointless setting

nixos/modules/services/misc/packagekit.nix

@@ -1,55 +1,60 @@
 { config, lib, pkgs, ... }:
 
-with lib;
-
 let
-
   cfg = config.services.packagekit;
 
-  packagekitConf = ''
-    [Daemon]
-    DefaultBackend=${cfg.backend}
-    KeepCache=false
-  '';
+  inherit (lib)
+    mkEnableOption mkOption mkIf mkRemovedOptionModule types
+    listToAttrs recursiveUpdate;
 
-  vendorConf = ''
-    [PackagesNotFound]
-    DefaultUrl=https://github.com/NixOS/nixpkgs
-    CodecUrl=https://github.com/NixOS/nixpkgs
-    HardwareUrl=https://github.com/NixOS/nixpkgs
-    FontUrl=https://github.com/NixOS/nixpkgs
-    MimeUrl=https://github.com/NixOS/nixpkgs
-  '';
+  iniFmt = pkgs.formats.ini { };
+
+  confFiles = [
+    (iniFmt.generate "PackageKit.conf" (recursiveUpdate
+      {
+        Daemon = {
+          DefaultBackend = "test_nop";
+          KeepCache = false;
+        };
+      }
+      cfg.settings))
+
+    (iniFmt.generate "Vendor.conf" (recursiveUpdate
+      {
+        PackagesNotFound = rec {
+          DefaultUrl = "https://github.com/NixOS/nixpkgs";
+          CodecUrl = DefaultUrl;
+          HardwareUrl = DefaultUrl;
+          FontUrl = DefaultUrl;
+          MimeUrl = DefaultUrl;
+        };
+      }
+      cfg.vendorSettings))
+  ];
 
 in
-
 {
+  imports = [
+    (mkRemovedOptionModule [ "services" "packagekit" "backend" ] "The only backend that doesn't blow up is `test_nop`.")
+  ];
 
-  options = {
+  options.services.packagekit = {
+    enable = mkEnableOption ''
+      PackageKit provides a cross-platform D-Bus abstraction layer for
+      installing software. Software utilizing PackageKit can install
+      software regardless of the package manager.
+    '';
 
-    services.packagekit = {
-      enable = mkEnableOption
-        ''
-          PackageKit provides a cross-platform D-Bus abstraction layer for
-          installing software. Software utilizing PackageKit can install
-          software regardless of the package manager.
-        '';
+    settings = mkOption {
+      type = iniFmt.type;
+      default = { };
+      description = "Additional settings passed straight through to PackageKit.conf";
+    };
 
-      # TODO: integrate with PolicyKit if the nix backend matures to the point
-      # where it will require elevated permissions
-      backend = mkOption {
-        type = types.enum [ "test_nop" ];
-        default = "test_nop";
-        description = ''
-          PackageKit supports multiple different backends and <literal>auto</literal> which
-          should do the right thing.
-          </para>
-          <para>
-          On NixOS however, we do not have a backend compatible with nix 2.0
-          (refer to <link xlink:href="https://github.com/NixOS/nix/issues/233">this issue</link> so we have to force
-          it to <literal>test_nop</literal> for now.
-        '';
-      };
+    vendorSettings = mkOption {
+      type = iniFmt.type;
+      default = { };
+      description = "Additional settings passed straight through to Vendor.conf";
     };
   };
 
@@ -59,7 +64,9 @@ in
 
     systemd.packages = with pkgs; [ packagekit ];
 
-    environment.etc."PackageKit/PackageKit.conf".text = packagekitConf;
-    environment.etc."PackageKit/Vendor.conf".text = vendorConf;
+    environment.etc = listToAttrs (map
+      (e:
+        lib.nameValuePair "PackageKit/${e.name}" { source = e; })
+      confFiles);
   };
 }