Improve documentation concerning message processors

[coffee-squirrel]

Summary

It would be helpful to have detailed information about the functionality and purpose of the default message processors ("Message Filter Chain" covers input extractors, etc.) and the impact the Message Processors Configuration order has on processing dependencies.

Context

Originally I wasn't quite sure what "Message Filter Chain" was, so it wasn't clear why my pipelines weren't working as expected. I've also seen others have similar issues in chat.

Expected Content

A description of the Message Filter Chain, Pipeline Processor, and GeoIP Resolver message processors, as well as a section discussing (in general) the importance of the message processor order.

For the Pipeline and GeoIP Resolver processors it might be better to just link to their existing sections (here and here, respectively).

Your Environment

• Graylog Version: 2.1.0+62db7e0

[CrazyLlama]

+1

Has there been any kind of update on this since? I'd love some deeper insight on this