Arbitrary metadata support

Description

It would be great to have arbitrary metadata for an event, which isn't passed through the output.

Example use case:
Fields like index_name, which are derived by a filter, and used by the elasticsearch output, but shouldn't be part of the event sent to Elasticsearch.

Environment

None

Status

Assignee

Logstash Developers

Reporter

Avleen Vig

Labels

None

Fix versions

Priority