nixos/udisks2: add freeform settings

nixos/modules/services/hardware/udisks2.nix

@@ -4,6 +4,13 @@
 
 with lib;
 
+let
+  settingsFormat = pkgs.formats.ini {
+    listToValue = concatMapStringsSep "," (generators.mkValueStringDefault {});
+  };
+  configFiles = mapAttrs (name: value: (settingsFormat.generate name value)) (mapAttrs' (name: value: nameValuePair name value ) config.services.udisks2.settings);
+in
+
 {
 
   ###### interface
@@ -21,6 +28,36 @@ with lib;
         '';
       };
 
+      settings = mkOption rec {
+        type = types.attrsOf settingsFormat.type;
+        apply = recursiveUpdate default;
+        default = {
+          "udisks2.conf" = {
+            udisks2 = {
+              modules = [ "*" ];
+              modules_load_preference = "ondemand";
+            };
+            defaults = {
+              encryption = "luks2";
+            };
+          };
+        };
+        example = literalExpression ''
+        {
+          "WDC-WD10EZEX-60M2NA0-WD-WCC3F3SJ0698.conf" = {
+            ATA = {
+              StandbyTimeout = 50;
+            };
+          };
+        };
+        '';
+        description = ''
+          Options passed to udisksd.
+          See <link xlink:href="http://manpages.ubuntu.com/manpages/latest/en/man5/udisks2.conf.5.html">here</link> and
+          drive configuration in <link xlink:href="http://manpages.ubuntu.com/manpages/latest/en/man8/udisks.8.html">here</link> for supported options.
+        '';
+      };
+
     };
 
   };
@@ -32,6 +69,8 @@ with lib;
 
     environment.systemPackages = [ pkgs.udisks2 ];
 
+    environment.etc = mapAttrs' (name: value: nameValuePair "udisks2/${name}" { source = value; } ) configFiles;
+
     security.polkit.enable = true;
 
     services.dbus.packages = [ pkgs.udisks2 ];