prune

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This is a community-maintained plugin! It does not ship with Logstash by default, but it is easy to install by running bin/logstash-plugin install logstash-filter-prune.

The prune filter is for removing fields from events based on whitelists or blacklist of field names or their values (names and values can also be regular expressions).

This can e.g. be useful if you have a json or kv filter that creates a number of fields with names that you don’t necessarily know the names of beforehand, and you only want to keep a subset of them.

 

Synopsis

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This plugin supports the following configuration options:

Required configuration options:

prune {
}

Available configuration options:

Setting Input type Required Default value

add_field

hash

No

{}

add_tag

array

No

[]

blacklist_names

array

No

["%{[^}]+}"]

blacklist_values

hash

No

{}

interpolate

boolean

No

false

periodic_flush

boolean

No

false

remove_field

array

No

[]

remove_tag

array

No

[]

whitelist_names

array

No

[]

whitelist_values

hash

No

{}

Details

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

blacklist_names

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  • Value type is array
  • Default value is ["%{[^}]+}"]

Exclude fields whose names match specified regexps, by default exclude unresolved %{field} strings.

    filter {
      prune {
        blacklist_names => [ "method", "(referrer|status)", "${some}_field" ]
      }
    }

blacklist_values

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  • Value type is hash
  • Default value is {}

Exclude specified fields if their values match one of the supplied regular expressions. In case field values are arrays, each array item is matched against the regular expressions and matching array items will be excluded.

    filter {
      prune {
        blacklist_values => [ "uripath", "/index.php",
                              "method", "(HEAD|OPTIONS)",
                              "status", "^[^2]" ]
      }
    }

interpolate

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  • Value type is boolean
  • Default value is false

Trigger whether configuration fields and values should be interpolated for dynamic values. Probably adds some performance overhead. Defaults to false.

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

whitelist_names

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  • Value type is array
  • Default value is []

Include only fields only if their names match specified regexps, default to empty list which means include everything.

    filter {
      prune {
        whitelist_names => [ "method", "(referrer|status)", "${some}_field" ]
      }
    }

whitelist_values

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  • Value type is hash
  • Default value is {}

Include specified fields only if their values match one of the supplied regular expressions. In case field values are arrays, each array item is matched against the regular expressions and only matching array items will be included.

    filter {
      prune {
        whitelist_values => [ "uripath", "/index.php",
                              "method", "(GET|POST)",
                              "status", "^[^2]" ]
      }
    }