Migrate packages module to clanServices

clanServices/packages/default.nix

@@ -0,0 +1,41 @@
+{ ... }:
+{
+  _class = "clan.service";
+  manifest.name = "clan-core/packages";
+  manifest.description = "Define package sets from nixpkgs and install them on one or more machines";
+  manifest.categories = [
+    "System"
+  ];
+
+  roles.default = {
+    interface =
+      { lib, ... }:
+      {
+        options.packages = lib.mkOption {
+
+          type = lib.types.listOf lib.types.str;
+          default = [ ];
+          example = [ "cowsay" ];
+          description = "The packages to install on the machine";
+        };
+      };
+
+    perInstance =
+      { settings, ... }:
+      {
+        nixosModule =
+          {
+            lib,
+            pkgs,
+            ...
+          }:
+          {
+
+            environment.systemPackages = map (
+              pName: lib.getAttrFromPath (lib.splitString "." pName) pkgs
+            ) settings.packages;
+          };
+      };
+  };
+
+}