_simulate endpoint for Logstash

[davidherst]

Ingest pipelines can be tested using the _simulate endpoint. But Logstash pipelines cannot.

To test a Logstash pipeline one must perform a "dry run" using test input.

A _simulate endpoint for Logstash that behaves the same way as for ingest pipelines would be very handy. It would also be a step toward more standardized (and easier to use) functionality.

[IanLee1521]

Definitely anything that can be done to make it easier to preview, save, replay, simulate, etc logs and what the processing will do to them as they go through Logstash would be a huge win. This for us is something that we have started looking at Cribl as a potential solution for. They have a very nice method for doing this capture, and live preview of logs as they are being processed.