Logstash Output

edit

The Logstash output sends the events directly to Logstash by using the lumberjack protocol, which runs over TCP. To use this option, you must install and configure the Beats input plugin for Logstash. Logstash allows for additional processing and routing of generated events.

Every event sent to Logstash contains additional metadata for indexing and filtering:

{
    ...
    "@metadata": {
      "beat": "<beat>",
      "type": "<event type>"
    }
}

In Logstash, you can configure the Elasticsearch output plugin to use the metadata and event type for indexing.

The following Logstash 1.5 configuration file sets Logstash to use the index and document type reported by Beats for indexing events into Elasticsearch. The index used will depend on the @timestamp field as identified by Logstash.

input {
  beats {
    port => 5044
  }
}

output {
  elasticsearch {
    host => "localhost"
    port => "9200"
    protocol => "http"
    index => "%{[@metadata][beat]}-%{+YYYY.MM.dd}"
    document_type => "%{[@metadata][type]}"
  }
}

Here is the same configuration for Logstash 2.x releases:

input {
  beats {
    port => 5044
  }
}

output {
  elasticsearch {
    hosts => ["http://localhost:9200"]
    index => "%{[@metadata][beat]}-%{+YYYY.MM.dd}"
    document_type => "%{[@metadata][type]}"
  }
}

Events indexed into Elasticsearch with the Logstash configuration shown here will be similar to events directly indexed by Beats into Elasticsearch.

Here is an example of how to configure the Beat to use Logstash:

output:
  logstash:
    hosts: ["localhost:5044"]

    # index configures '@metadata.beat' field to be used by Logstash for
    # indexing. The default index name depends on the each beat.
    # For Packetbeat, the default is set to packetbeat, for Topbeat to
    # topbeat and for Filebeat to filebeat.
    index: filebeat

Logstash Output Options

edit

You can specify the following options in the logstash section:

hosts

edit

The list of known Logstash servers to connect to. All entries in this list can contain a port number. If no port number is given, the value specified for port is used as the default port number.

compression_level

edit

The gzip compression level. Setting this value to values less than or equal to 0 disables compression. The compression level must be in the range of 1 (best speed) to 9 (best compression).

The default value is 3.

worker

edit

The number of workers per configured host publishing events to Logstash. This is best used with load balancing mode enabled. Example: If you have 2 hosts and 3 workers, in total 6 workers are started (3 for each host).

loadbalance

edit

If set to true and multiple Logstash hosts are configured, the output plugin load balances published events onto all Logstash hosts. If set to false, the output plugin sends all events to only one host (determined at random) and will switch to another host if the selected one becomes unresponsive. The default value is false.

output:
  logstash:
    hosts: ["localhost:5044", "localhost:5045"]

    # configure logstash plugin to loadbalance events between the logstash instances
    loadbalance: true

    # configure index prefix name
    index: filebeat

port

edit

The default port to use if the port number is not given in hosts. The default port number is 10200.

index

edit

The index root name to write events to. The default is the Beat name. For example "filebeat" generates "[filebeat-]YYYY.MM.DD" indexes (for example, "filebeat-2015.04.26").

tls

edit

Configuration options for TLS parameters like the root CA for Logstash connections. See TLS Options for more information. To use TLS, you must also configure the Beats input plugin for Logstash to use SSL/TLS.

timeout

edit

The number of seconds to wait for responses from the Logstash server before timing out. The default is 30 (seconds).

max_retries

edit

The number of times to retry publishing an event after a publishing failure. After the specified number of retries, the events are typically dropped. Some Beats, such as Filebeat, ignore the max_retries setting and retry until all events are published.

Set max_retries to a value less than 0 to retry until all events are published.

The default is 3.

bulk_max_size

edit

The maximum number of events to bulk in a single Logstash request. The default is 2048.

If the Beat sends single events, the events are collected into batches. If the Beat publishes a large batch of events (larger than the value specified by bulk_max_size), the batch is split.

Specifying a larger batch size can improve performance by lowering the overhead of sending events. However big batch sizes can also increase processing times, which might result in API errors, killed connections, timed-out publishing requests, and, ultimately, lower throughput.

Setting bulk_max_size to values less than or equal to 0 disables buffering in libbeat. When buffering is disabled, Beats that publish single events (such as Packetbeat and Topbeat) send each event directly to Elasticsearch. Beats that publish data in batches (such as Filebeat) send events in batches based on the spooler size.