throttle

Milestone: 1

The throttle filter is for throttling the number of events received. The filter is configured with a lower bound, the before_count, and upper bound, the after_count, and a period of time. All events passing through the filter will be counted based on a key. As long as the count is less than the before_count or greater than the after_count, the event will be “throttled” which means the filter will be considered successful and any tags or fields will be added.

For example, if you wanted to throttle events so you only receive an event after 2 occurrences and you get no more than 3 in 10 minutes, you would use the configuration: period => 600 before_count => 3 after_count => 5

Which would result in: event 1 - throttled (successful filter, period start) event 2 - throttled (successful filter) event 3 - not throttled event 4 - not throttled event 5 - not throttled event 6 - throttled (successful filter) event 7 - throttled (successful filter) event x - throttled (successful filter) period end event 1 - throttled (successful filter, period start) event 2 - throttled (successful filter) event 3 - not throttled event 4 - not throttled event 5 - not throttled event 6 - throttled (successful filter) …

Another example is if you wanted to throttle events so you only receive 1 event per hour, you would use the configuration: period => 3600 before_count => -1 after_count => 1

Which would result in: event 1 - not throttled (period start) event 2 - throttled (successful filter) event 3 - throttled (successful filter) event 4 - throttled (successful filter) event x - throttled (successful filter) period end event 1 - not throttled (period start) event 2 - throttled (successful filter) event 3 - throttled (successful filter) event 4 - throttled (successful filter) …

A common use case would be to use the throttle filter to throttle events before 3 and after 5 while using multiple fields for the key and then use the drop filter to remove throttled events. This configuration might appear as:

filter {
  throttle {
    before_count => 3
    after_count => 5
    period => 3600
    key => "%{host}%{message}"
    add_tag => "throttled"
  }
  if "throttled" in [tags] {
    drop { }
  }
}

Another case would be to store all events, but only email non-throttled events so the op’s inbox isn’t flooded with emails in the event of a system error. This configuration might appear as:

filter {
  throttle {
    before_count => 3
    after_count => 5
    period => 3600
    key => "%{message}"
    add_tag => "throttled"
  }
}
output {
  if "throttled" not in [tags] {
    email {
   	    from => "logstash@mycompany.com"
   	    subject => "Production System Alert"
   	    to => "ops@mycompany.com"
   	    via => "sendmail"
   	    body => "Alert on %{host} from path %{path}:\n\n%{message}"
   	    options => { "location" => "/usr/sbin/sendmail" }
    }
  }
  elasticsearch_http {
    host => "localhost"
    port => "19200"
  }
}

The event counts are cleared after the configured period elapses since the first instance of the event. That is, all the counts don’t reset at the same time but rather the throttle period is per unique key value.

Mike Pilone (@mikepilone)

Synopsis

This is what it might look like in your config file:
filter {
  throttle {
    add_field => ... # hash (optional), default: {}
    add_tag => ... # array (optional), default: []
    after_count => ... # number (optional), default: -1
    before_count => ... # number (optional), default: -1
    key => ... # string (required)
    max_counters => ... # number (optional), default: 100000
    period => ... # string (optional), default: "3600"
    remove_field => ... # array (optional), default: []
    remove_tag => ... # array (optional), default: []
  }
}

Details

add_field

  • Value type is hash
  • Default value is {}

If this filter is successful, add any arbitrary fields to this event. Field names can be dynamic and include parts of the event using the %{field} Example:

filter {
  throttle {
    add_field => { "foo_%{somefield}" => "Hello world, from %{host}" }
  }
}

# You can also add multiple fields at once:

filter {
  throttle {
    add_field => { 
      "foo_%{somefield}" => "Hello world, from %{host}"
      "new_field" => "new_static_value"
    }
  }
}

If the event has field “somefield” == “hello” this filter, on success, would add field “foo_hello” if it is present, with the value above and the %{host} piece replaced with that value from the event. The second example would also add a hardcoded field.

add_tag

  • Value type is array
  • Default value is []

If this filter is successful, add arbitrary tags to the event. Tags can be dynamic and include parts of the event using the %{field} syntax. Example:

filter {
  throttle {
    add_tag => [ "foo_%{somefield}" ]
  }
}

# You can also add multiple tags at once:
filter {
  throttle {
    add_tag => [ "foo_%{somefield}", "taggedy_tag"]
  }
}

If the event has field “somefield” == “hello” this filter, on success, would add a tag “foo_hello” (and the second example would of course add a “taggedy_tag” tag).

after_count

  • Value type is number
  • Default value is -1

Events greater than this count will be throttled. Setting this value to -1, the default, will cause no messages to be throttled based on the upper bound.

before_count

  • Value type is number
  • Default value is -1

Events less than this count will be throttled. Setting this value to -1, the default, will cause no messages to be throttled based on the lower bound.

exclude_tags DEPRECATED

  • DEPRECATED WARNING: This config item is deprecated. It may be removed in a further version.
  • Value type is array
  • Default value is []

Only handle events without all/any (controlled by exclude_any config option) of these tags. Optional.

key (required setting)

  • Value type is string
  • There is no default value for this setting.

The name to use in configuration files. New plugins should start life at milestone 1. The key used to identify events. Events with the same key will be throttled as a group. Field substitutions are allowed, so you can combine multiple fields.

max_counters

  • Value type is number
  • Default value is 100000

The maximum number of counters to store before the oldest counter is purged. Setting this value to -1 will prevent an upper bound no constraint on the number of counters
and they will only be purged after expiration. This configuration value should only be used as a memory control mechanism and can cause early counter expiration if the value is reached. It is recommended to leave the default value and ensure that your key is selected such that it limits the number of counters required (i.e. don’t use UUID as the key!)

period

  • Value type is string
  • Default value is "3600"

The period in seconds after the first occurrence of an event until the count is reset for the event. This period is tracked per unique key value. Field substitutions are allowed in this value. They will be evaluated when the first event for a given key is seen. This allows you to specify that certain kinds of events throttle for a specific period.

remove_field

  • Value type is array
  • Default value is []

If this filter is successful, remove arbitrary fields from this event. Fields names can be dynamic and include parts of the event using the %{field} Example:

filter {
  throttle {
    remove_field => [ "foo_%{somefield}" ]
  }
}

# You can also remove multiple fields at once:

filter {
  throttle {
    remove_field => [ "foo_%{somefield}" "my_extraneous_field" ]
  }
}

If the event has field “somefield” == “hello” this filter, on success, would remove the field with name “foo_hello” if it is present. The second example would remove an additional, non-dynamic field.

remove_tag

  • Value type is array
  • Default value is []

If this filter is successful, remove arbitrary tags from the event. Tags can be dynamic and include parts of the event using the %{field} syntax. Example:

filter {
  throttle {
    remove_tag => [ "foo_%{somefield}" ]
  }
}

# You can also remove multiple tags at once:

filter {
  throttle {
    remove_tag => [ "foo_%{somefield}", "sad_unwanted_tag"]
  }
}

If the event has field “somefield” == “hello” this filter, on success, would remove the tag “foo_hello” if it is present. The second example would remove a sad, unwanted tag as well.

tags DEPRECATED

  • DEPRECATED WARNING: This config item is deprecated. It may be removed in a further version.
  • Value type is array
  • Default value is []

Only handle events with all/any (controlled by include_any config option) of these tags. Optional.

type DEPRECATED

  • DEPRECATED WARNING: This config item is deprecated. It may be removed in a further version.
  • Value type is string
  • Default value is ""

Note that all of the specified routing options (type,tags.exclude_tags,include_fields,exclude_fields) must be met in order for the event to be handled by the filter. The type to act on. If a type is given, then this filter will only act on messages with the same type. See any input plugin’s “type” attribute for more. Optional.


This is documentation from lib/logstash/filters/throttle.rb