anchor.diff:          type = types.str;
           default = "mysql";
           description = "User account under which MySQL runs";
  +      };
  +
  +      group = mkOption {
  +        type = types.str;
  +        default = "mysql";
  +        description = "Group under which MySQL runs.";
         };
   
         dataDir = mkOption {
  
positive.code:               "+${setupScript}";
            # User and group
            User = cfg.user;
            Group = "mysql";
            # Runtime directory and mode
            RuntimeDirectory = "mysqld";
            RuntimeDirectoryMode = "0755";
  
negative.code:       })
      ];
  
      users.users = optionalAttrs (cfg.user == "mysql") {
        mysql = {
          description = "MySQL server user";
          group = cfg.group;
          uid = config.ids.uids.mysql;
        };
      };
  
      users.groups = optionalAttrs (cfg.group == "mysql") {
        mysql.gid = config.ids.gids.mysql;
      };
  
      environment.systemPackages = [ cfg.package ];
  
      environment.etc."my.cnf".source = cfg.configFile;
  
      systemd.tmpfiles.rules = [
        "d '${cfg.dataDir}' 0700 '${cfg.user}' '${cfg.group}' - -"
        "z '${cfg.dataDir}' 0700 '${cfg.user}' '${cfg.group}' - -"
      ];
  
      systemd.services.mysql = let
  