xsettingsd: make configurable through module

modules/services/xsettingsd.nix

@@ -6,6 +6,20 @@ let
 
   cfg = config.services.xsettingsd;
 
+  renderSettings = settings:
+    concatStrings (mapAttrsToList renderSetting settings);
+
+  renderSetting = key: value: ''
+    ${key} ${renderValue value}
+  '';
+
+  renderValue = value:
+    {
+      int = toString value;
+      bool = if value then "1" else "0";
+      string = ''"${value}"'';
+    }.${builtins.typeOf value};
+
 in {
   meta.maintainers = [ maintainers.imalison ];
 
@@ -21,6 +35,34 @@ in {
           Package containing the <command>xsettingsd</command> program.
         '';
       };
+
+      settings = mkOption {
+        type = with types; attrsOf (oneOf [ bool int str ]);
+        default = { };
+        example = literalExample ''
+          {
+            "Net/ThemeName" = "Numix";
+            "Xft/Antialias" = true;
+            "Xft/Hinting" = true;
+            "Xft/RGBA" = "rgb";
+          }
+        '';
+        description = ''
+          Xsettingsd options for configuration file. See
+          <link xlink:href="https://github.com/derat/xsettingsd/wiki/Settings"/>
+          for documentation on these values.
+        '';
+      };
+
+      configFile = mkOption {
+        type = types.nullOr types.package;
+        internal = true;
+        readOnly = true;
+        default = if cfg.settings == { } then
+          null
+        else
+          pkgs.writeText "xsettingsd.conf" (renderSettings cfg.settings);
+      };
     };
   };
 
@@ -41,7 +83,9 @@ in {
 
       Service = {
         Environment = "PATH=${config.home.profileDirectory}/bin";
-        ExecStart = "${cfg.package}/bin/xsettingsd";
+        ExecStart = "${cfg.package}/bin/xsettingsd"
+          + optionalString (cfg.configFile != null)
+          " -c ${escapeShellArg cfg.configFile}";
         Restart = "on-abort";
       };
     };

tests/default.nix

@@ -139,6 +139,7 @@ import nmt {
     ./modules/services/window-managers/i3
     ./modules/services/window-managers/sway
     ./modules/services/wlsunset
+    ./modules/services/xsettingsd
     ./modules/systemd
     ./modules/targets-linux
   ] ++ lib.optionals enableBig [

tests/modules/services/xsettingsd/basic-configuration.conf

@@ -0,0 +1,4 @@
+Net/ThemeName "Numix"
+Xft/Antialias 1
+Xft/Hinting 1
+Xft/RGBA "rgb"

tests/modules/services/xsettingsd/basic-configuration.nix

@@ -0,0 +1,26 @@
+{ config, pkgs, ... }:
+
+{
+  config = {
+    services.xsettingsd = {
+      enable = true;
+      package = config.lib.test.mkStubPackage { };
+      settings = {
+        "Net/ThemeName" = "Numix";
+        "Xft/Antialias" = true;
+        "Xft/Hinting" = true;
+        "Xft/RGBA" = "rgb";
+      };
+    };
+    nmt.script = ''
+      serviceFile=home-files/.config/systemd/user/xsettingsd.service
+
+      assertFileExists $serviceFile
+      assertFileRegex $serviceFile 'ExecStart=.*/bin/xsettingsd.*'
+
+      assertFileExists ${config.services.xsettingsd.configFile}
+      assertFileContent ${config.services.xsettingsd.configFile} \
+        ${./basic-configuration.conf}
+    '';
+  };
+}

tests/modules/services/xsettingsd/default.nix

@@ -0,0 +1 @@
+{ xsettingsd-basic-configuration = ./basic-configuration.nix; }