anchor.diff:          default = [ ];
           example = literalExample "[ pkgs.logstash-contrib ]";
           description = "The paths to find other logstash plugins in.";
  +      };
  +
  +      logLevel = mkOption {
  +        type = types.enum [ "debug" "info" "warn" "error" "fatal" ];
  +        default = "warn";
  +        description = "Logging verbosity level.";
         };
   
         watchdogTimeout = mkOption {
  
positive.code:           "${cfg.package}/bin/logstash agent " +
            "-w ${toString cfg.filterWorkers} " +
            ops havePluginPath "--pluginpath ${pluginPath} " +
            "--watchdog-timeout ${toString cfg.watchdogTimeout} " +
            "-f ${writeText "logstash.conf" ''
              input {
  
negative.code:   pluginPath = lib.concatStringsSep ":" cfg.plugins;
    havePluginPath = lib.length cfg.plugins > 0;
    ops = lib.optionalString;
    verbosityFlag = {
      debug = "--debug";
      info  = "--verbose";
      warn  = ""; # intentionally empty
      error = "--quiet";
      fatal = "--silent";
    }."${cfg.logLevel}";
  
  in
  
  