:plugin: metrics
:type: filter

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:version: %VERSION%
:release_date: %RELEASE_DATE%
:changelog_url: %CHANGELOG_URL%
:include_path: ../../../../logstash/docs/include
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[id="plugins-{type}s-{plugin}"]

=== Metrics filter plugin

include::{include_path}/plugin_header.asciidoc[]

==== Description

The metrics filter is useful for aggregating metrics.

IMPORTANT: Elasticsearch 2.0 no longer allows field names with dots. Version 3.0
of the metrics filter plugin changes behavior to use nested fields rather than
dotted notation to avoid colliding with versions of Elasticsearch 2.0+.  Please
note the changes in the documentation (underscores and sub-fields used).

For example, if you have a field `response` that is
a http response code, and you want to count each
kind of response, you can do this:
[source,ruby]
    filter {
      metrics {
        meter => [ "http_%{response}" ]
        add_tag => "metric"
      }
    }

Metrics are flushed every 5 seconds by default or according to
`flush_interval`. Metrics appear as
new events in the event stream and go through any filters
that occur after as well as outputs.

In general, you will want to add a tag to your metrics and have an output
explicitly look for that tag.

The event that is flushed will include every 'meter' and 'timer'
metric in the following way:

==== `meter` values

For a `meter => "thing"` you will receive the following fields:

* "[thing][count]" - the total count of events
* "[thing][rate_1m]" - the per-second event rate in a 1-minute sliding window
* "[thing][rate_5m]" - the per-second event rate in a 5-minute sliding window
* "[thing][rate_15m]" - the per-second event rate in a 15-minute sliding window

==== `timer` values

For a `timer => { "thing" => "%{duration}" }` you will receive the following fields:

* "[thing][count]" - the total count of events
* "[thing][rate_1m]" - the per-second average value in a 1-minute sliding window
* "[thing][rate_5m]" - the per-second average value in a 5-minute sliding window
* "[thing][rate_15m]" - the per-second average value in a 15-minute sliding window
* "[thing][min]" - the minimum value seen for this metric
* "[thing][max]" - the maximum value seen for this metric
* "[thing][stddev]" - the standard deviation for this metric
* "[thing][mean]" - the mean for this metric
* "[thing][pXX]" - the XXth percentile for this metric (see `percentiles`)

The default lengths of the event rate window (1, 5, and 15 minutes)
can be configured with the `rates` option.

==== Example: Computing event rate

For a simple example, let's track how many events per second are running
through logstash:
[source,ruby]
----
    input {
      generator {
        type => "generated"
      }
    }

    filter {
      if [type] == "generated" {
        metrics {
          meter => "events"
          add_tag => "metric"
        }
      }
    }

    output {
      # only emit events with the 'metric' tag
      if "metric" in [tags] {
        stdout {
          codec => line {
            format => "rate: %{[events][rate_1m]}"
          }
        }
      }
    }
----

Running the above:
[source,ruby]
    % bin/logstash -f example.conf
    rate: 23721.983566819246
    rate: 24811.395722536377
    rate: 25875.892745934525
    rate: 26836.42375967113

We see the output includes our events' 1-minute rate.

In the real world, you would emit this to graphite or another metrics store,
like so:
[source,ruby]
    output {
      graphite {
        metrics => [ "events.rate_1m", "%{[events][rate_1m]}" ]
      }
    }

[id="plugins-{type}s-{plugin}-options"]
==== Metrics Filter Configuration Options

This plugin supports the following configuration options plus the <<plugins-{type}s-{plugin}-common-options>> described later.

[cols="<,<,<",options="header",]
|=======================================================================
|Setting |Input type|Required
| <<plugins-{type}s-{plugin}-clear_interval>> |<<number,number>>|No
| <<plugins-{type}s-{plugin}-flush_interval>> |<<number,number>>|No
| <<plugins-{type}s-{plugin}-ignore_older_than>> |<<number,number>>|No
| <<plugins-{type}s-{plugin}-meter>> |<<array,array>>|No
| <<plugins-{type}s-{plugin}-percentiles>> |<<array,array>>|No
| <<plugins-{type}s-{plugin}-rates>> |<<array,array>>|No
| <<plugins-{type}s-{plugin}-timer>> |<<hash,hash>>|No
|=======================================================================

Also see <<plugins-{type}s-{plugin}-common-options>> for a list of options supported by all
filter plugins.

&nbsp;

[id="plugins-{type}s-{plugin}-clear_interval"]
===== `clear_interval` 

  * Value type is <<number,number>>
  * Default value is `-1`

The clear interval, when all counters are reset.

If set to -1, the default value, the metrics will never be cleared.
Otherwise, should be a multiple of 5s.

[id="plugins-{type}s-{plugin}-flush_interval"]
===== `flush_interval` 

  * Value type is <<number,number>>
  * Default value is `5`

The flush interval, when the metrics event is created. Must be a multiple of 5s.

[id="plugins-{type}s-{plugin}-ignore_older_than"]
===== `ignore_older_than` 

  * Value type is <<number,number>>
  * Default value is `0`

Don't track events that have `@timestamp` older than some number of seconds.

This is useful if you want to only include events that are near real-time
in your metrics.

For example, to only count events that are within 10 seconds of real-time, you
would do this:

    filter {
      metrics {
        meter => [ "hits" ]
        ignore_older_than => 10
      }
    }

[id="plugins-{type}s-{plugin}-meter"]
===== `meter` 

  * Value type is <<array,array>>
  * Default value is `[]`

syntax: `meter => [ "name of metric", "name of metric" ]`

[id="plugins-{type}s-{plugin}-percentiles"]
===== `percentiles` 

  * Value type is <<array,array>>
  * Default value is `[1, 5, 10, 90, 95, 99, 100]`

The percentiles that should be measured and emitted for timer values.

[id="plugins-{type}s-{plugin}-rates"]
===== `rates` 

  * Value type is <<array,array>>
  * Default value is `[1, 5, 15]`

The rates that should be measured, in minutes.
Possible values are 1, 5, and 15.

[id="plugins-{type}s-{plugin}-timer"]
===== `timer` 

  * Value type is <<hash,hash>>
  * Default value is `{}`

syntax: `timer => [ "name of metric", "%{time_value}" ]`



[id="plugins-{type}s-{plugin}-common-options"]
include::{include_path}/{type}.asciidoc[]
