Memcached filter plugin

• Plugin version: v1.2.0
• Released on: 2023-01-18
• Changelog

For other versions, see the Versioned plugin docs.

For questions about the plugin, open a topic in the Discuss forums. For bugs or feature requests, open an issue in Github. For the list of Elastic supported plugins, please consult the Elastic Support Matrix.

The Memcached filter provides integration with external data in Memcached.

It currently provides the following facilities:

• get: get values for one or more memcached keys and inject them into the event at the provided paths
• set: set values from the event to the corresponding memcached keys

This plugin enables key/value lookup enrichment against a Memcached object caching system. You can use this plugin to query for a value, and set it if not found.

memcached {
    hosts => ["localhost"]
    namespace => "convert_mm"
    get => {
      "%{millimeters}" => "[inches]"
    }
    add_tag => ["from_cache"]
    id => "memcached-get"
  }

memcached {
    hosts => ["localhost"]
    namespace => "convert_mm"
    set => {
      "[inches]" => "%{millimeters}"
    }
    id => "memcached-set"
  }

This plugin supports the following configuration options plus the Common options described later.

Also see Common options for a list of options supported by all filter plugins.

• Value type is array
• Default value is localhost

The hosts parameter accepts an array of addresses corresponding to memcached instances.

Hosts can be specified via FQDN (e.g., example.com), an IPV4 address (e.g., 123.45.67.89), or an IPV6 address (e.g. ::1 or 2001:0db8:85a3:0000:0000:8a2e:0370:7334). If your memcached host uses a non-standard port, the port can be specified by appending a colon (:) and the port number; to include a port with an IPv6 address, the address must first be wrapped in square-brackets ([ and ]), e.g., [::1]:11211.

If more than one host is specified, requests will be distributed to the given hosts using a modulus of the CRC-32 checksum of each key.

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

If specified, prefix all memcached keys with the given string followed by a colon (:); this is useful if all keys being used by this plugin share a common prefix.

Example:

In the following configuration, we would GET fruit:banana and fruit:apple from memcached:

filter {
  memcached {
    namespace => "fruit"
    get => {
      "banana" => "[fruit-stats][banana]"
      "apple"  => "[fruit-stats][apple]
    }
  }
}

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

If specified, get the values for the given keys from memcached, and store them in the corresponding fields on the event.

• keys are interpolated (e.g., if the event has a field foo with value bar, the key sand/%{{foo}} will evaluate to sand/bar)
• fields can be nested references

filter {
  memcached {
    get => {
      "memcached-key-1" => "field1"
      "memcached-key-2" => "[nested][field2]"
    }
  }
}

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

If specified, extracts the values from the given event fields, and sets the corresponding keys to those values in memcached with the configured ttl

• keys are interpolated (e.g., if the event has a field foo with value bar, the key sand/%{{foo}} will evaluate to sand/bar)
• fields can be nested references

filter {
  memcached {
    set => {
      "field1"           => "memcached-key-1"
      "[nested][field2]" => "memcached-key-2"
    }
  }
}

• Value type is string
• The default value for this setting is _memcached_failure.

When a memcached operation causes a runtime exception to be thrown within the plugin, the operation is safely aborted without crashing the plugin, and the event is tagged with the provided value.

For usages of this plugin that persist data to memcached (e.g., set), the time-to-live in seconds

• Value type is number
• The default value is 0 (no expiry)

These configuration options are supported by all filter plugins:

• 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 {
  memcached {
    add_field => { "foo_%{somefield}" => "Hello world, from %{host}" }
  }
}

# You can also add multiple fields at once:
filter {
  memcached {
    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.

• 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 {
  memcached {
    add_tag => [ "foo_%{somefield}" ]
  }
}

# You can also add multiple tags at once:
filter {
  memcached {
    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).

• Value type is boolean
• Default value is true

Disable or enable metric logging for this specific plugin instance. By default we record all the metrics we can, but you can disable metrics collection for a specific plugin.

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

Add a unique ID to the plugin configuration. If no ID is specified, Logstash will generate one. It is strongly recommended to set this ID in your configuration. This is particularly useful when you have two or more plugins of the same type, for example, if you have 2 memcached filters. Adding a named ID in this case will help in monitoring Logstash when using the monitoring APIs.

filter {
  memcached {
    id => "ABC"
  }
}

• Value type is boolean
• Default value is false

Call the filter flush method at regular interval. Optional.

• 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 {
  memcached {
    remove_field => [ "foo_%{somefield}" ]
  }
}

# You can also remove multiple fields at once:
filter {
  memcached {
    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.

• 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 {
  memcached {
    remove_tag => [ "foo_%{somefield}" ]
  }
}

# You can also remove multiple tags at once:
filter {
  memcached {
    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.