ifTheuExist and extra groups to user sam

hosts/common/users/admin/default.nix

@@ -1,5 +1,6 @@
 { pkgs, inputs, config, lib, ... }:
 let
+  ifTheyExist = groups: builtins.filter (group: builtins.hasAttr group config.users.groups) groups;
   username = "admin";
   pubKeys = lib.filesystem.listFilesRecursive (../keys);
   hostname = config.networking.hostName;
@@ -15,7 +16,13 @@ in
     hashedPasswordFile = sopsHashedPasswordFile;
     openssh.authorizedKeys.keys = lib.lists.forEach pubKeys (key: builtins.readFile key);
 
-    extraGroups = ["wheel"]; 
+    extraGroups = [
+      "wheel"
+    ] ++ ifTheyExist [
+      "docker"
+      "lxc"
+      "git"
+    ];
 
     packages = with pkgs; [
     ];