anchor.diff:        description = "Listening port.";
         default = 3000;
         type = types.int;
  +    };
  +
  +    socket = mkOption {
  +      description = "Listening socket.";
  +      default = "/run/grafana/grafana.sock";
  +      type = types.str;
       };
   
       domain = mkOption {
  
positive.code:       serviceConfig = {
          WorkingDirectory = cfg.dataDir;
          User = "grafana";
        };
        preStart = ''
          ln -fs ${cfg.package}/share/grafana/conf ${cfg.dataDir}
  
negative.code:     SERVER_PROTOCOL = cfg.protocol;
      SERVER_HTTP_ADDR = cfg.addr;
      SERVER_HTTP_PORT = cfg.port;
      SERVER_SOCKET = cfg.socket;
      SERVER_DOMAIN = cfg.domain;
      SERVER_ROOT_URL = cfg.rootUrl;
      SERVER_STATIC_ROOT_PATH = cfg.staticRootPath;
  