I already have Logstash configured to directly pick up files (Gatling logs), process them using custom logic, and send to Elasticsearch. And it's working fine. I'm now trying to setup Filebeat to send the files to it instead.
The basics seem to work as I see the new entires ending up in Elasticsearch, but they look all wrong. My theory is that Logstash is configured to parse Gatling logs, but Filebeat doesn't send the logs directly, but some JSON or other format containing the metadata as well, and Logstash needs to be reconfigured to parse this instead.
But... how do I find out what Filebeat is sending? Is the format documented somewhere?