anchor.diff:        };
   
         filterConfig = mkOption {
  +        type = types.lines;
           default = ''noop {}'';
  -        description = "logstash filter configuration";
  +        description = "logstash filter configuration.";
           example = ''
             if [type] == "syslog" {
               # Keep only relevant systemd fields
  
positive.code:       };
  
        outputConfig = mkOption {
          default = ''stdout { debug => true debug_format => "json"}'';
          description = "Logstash output configuration";
          example = ''
            redis { host => "localhost" data_type => "list" key => "logstash" codec => json }
            elasticsearch { embedded => true }
          '';
        };
      };
    };
  
  
negative.code:   ###### interface
  
    options = {
  
      services.logstash = {
  
        enable = mkOption {
          type = types.bool;
          default = false;
          description = "Enable logstash.";
        };
  
        enableWeb = mkOption {
          type = types.bool;
          default = false;
          description = "Enable the logstash web interface.";
        };
  
        inputConfig = mkOption {
          type = types.lines;
          default = ''stdin { type => "example" }'';
          description = "Logstash input configuration.";
          example = ''
            # Read from journal
            pipe {
  