add vaultwarden, not activated

modules/services/vaultwarden.nix

@@ -0,0 +1,24 @@
+{ config, pkgs, lib, ... }: {
+
+  options = {
+
+    vaultwardenServer = lib.mkOption {
+      description = "Hostname for Vaultwarden.";
+      type = lib.types.str;
+    };
+
+  };
+
+  config = {
+    services.vaultwarden = {
+      enable = true;
+      config = {
+        DOMAIN = config.vaultwardenServer;
+        SIGNUPS_ALLOWED = false;
+      };
+      environmentFile = null;
+      dbBackend = "sqlite";
+    };
+  };
+
+}