stuff?

hosts/common/optional/docker.nix

@@ -0,0 +1,5 @@
+{
+  virtualisation.docker = {
+    enable = true;
+  };
+}

hosts/common/users/luna/default.nix

@@ -2,23 +2,25 @@
   pkgs,
   config,
   ...
-}: {
+}: let
+  ifTheyExist = groups: builtins.filter (group: builtins.hasAttr group config.users.groups) groups;
+in {
   # Define a user account. Don't forget to set a password with ‘passwd’.
   users.users.luna = {
     isNormalUser = true;
     description = "luna";
     shell = pkgs.zsh;
-    extraGroups = [
+    extraGroups = ifTheyExist [
+      "audio"
+      "docker"
       "networkmanager"
       "wheel"
     ];
     packages = with pkgs; [
       #  thunderbird
       gnome-software
-      git
       neovim
       rustup
-      vscode.fhs
       protonvpn-gui
     ];
   };