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dns

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dns

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The DNS filter performs a lookup (either an A record/CNAME record lookup or a reverse lookup at the PTR record) on records specified under the reverse and resolve arrays.

The config should look like this:

    filter {
      dns {
        type => 'type'
        reverse => [ "source_host", "field_with_address" ]
        resolve => [ "field_with_fqdn" ]
        action => "replace"
      }
    }

This filter, like all filters, only processes 1 event at a time, so the use of this plugin can significantly slow down your pipeline’s throughput if you have a high latency network. By way of example, if each DNS lookup takes 2 milliseconds, the maximum throughput you can achieve with a single filter worker is 500 events per second (1000 milliseconds / 2 milliseconds).

Synopsis

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This plugin supports the following configuration options:

Required configuration options:

dns {
}

Available configuration options:

Setting	Input type	Required	Default value
`action`	string, one of `["append", "replace"]`	No	`"append"`
`add_field`	hash	No	`{}`
`add_tag`	array	No	`[]`
`failed_cache_size`	number	No	`0`
`failed_cache_ttl`	number	No	`5`
`hit_cache_size`	number	No	`0`
`hit_cache_ttl`	number	No	`60`
`max_retries`	number	No	`2`
`nameserver`	array	No
`periodic_flush`	boolean	No	`false`
`remove_field`	array	No	`[]`
`remove_tag`	array	No	`[]`
`resolve`	array	No
`reverse`	array	No
`timeout`	number	No	`0.5`

Details

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`action`

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Value can be any of: append, replace
Default value is "append"

Determine what action to do: append or replace the values in the fields specified under reverse and resolve.

`add_field`

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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 {
      dns {
        add_field => { "foo_%{somefield}" => "Hello world, from %{host}" }
      }
    }
[source,ruby]
    # You can also add multiple fields at once:
    filter {
      dns {
        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`

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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 {
      dns {
        add_tag => [ "foo_%{somefield}" ]
      }
    }
[source,ruby]
    # You can also add multiple tags at once:
    filter {
      dns {
        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).

`failed_cache_size`

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Value type is number
Default value is 0

cache size for failed requests

`failed_cache_ttl`

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Value type is number
Default value is 5

how long to cache failed requests (in seconds)

`hit_cache_size`

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Value type is number
Default value is 0

set the size of cache for successful requests

`hit_cache_ttl`

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Value type is number
Default value is 60

how long to cache successful requests (in seconds)

`max_retries`

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Value type is number
Default value is 2

number of times to retry a failed resolve/reverse

`nameserver`

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Value type is array
There is no default value for this setting.

Use custom nameserver(s). For example: ["8.8.8.8", "8.8.4.4"]

`periodic_flush`

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Value type is boolean
Default value is false

Call the filter flush method at regular interval. Optional.

`remove_field`

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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 {
      dns {
        remove_field => [ "foo_%{somefield}" ]
      }
    }
[source,ruby]
    # You can also remove multiple fields at once:
    filter {
      dns {
        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`

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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 {
      dns {
        remove_tag => [ "foo_%{somefield}" ]
      }
    }
[source,ruby]
    # You can also remove multiple tags at once:
    filter {
      dns {
        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.

`resolve`

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Value type is array
There is no default value for this setting.

Forward resolve one or more fields.

`reverse`

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Value type is array
There is no default value for this setting.

TODO(sissel): The timeout limitation does seem to be fixed in here: http://redmine.ruby-lang.org/issues/5100 # but isn’t currently in JRuby. TODO(sissel): make action required? This was always the intent, but it due to a typo it was never enforced. Thus the default behavior in past versions was append by accident. Reverse resolve one or more fields.

`timeout`

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Value type is number
Default value is 0.5

resolv calls will be wrapped in a timeout instance

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