Documenting content-type header integration compatibility

[acchen97]

We should have some documentation around ES compatibility with the inclusion of content-type http headers option.

If users want to use LS versions 2.4 - 5.2 with ES 5.3+ (with content-type headers are turned on), they will need to update their ES related plugins to:

• ES output - 6.2.5+
• ES input - 4.0.2+
• ES filter - 3.1.1+

We should decide where the best place is to put this. Here's an proposal:

• Include a statement in each of the 3 plugins
• Perhaps reference this as a client compatibility caveat on the ES side

/cc @dedemorton @suyograo @jordansissel

[dedemorton]

@acchen97 Ok, I've added info to the source for the plugin docs. I am concerned that this info will be overlooked, though. I hope there's some error messaging that will help users figure out this problem because I worry that they won't see this in the doc.

@debadair Do you have any suggestions for how to document this on the Elasticsearch side? The gist is that setting http.content_type.required to true is going to break older Logstash Elasticsearch plugins that don't yet support sending Content-Type headers.

[acchen97]

@dedemorton can we close this? The cross-referencing docs on the ES side are a nice to have as turning on the requirement for content typer headers is optional.

[dedemorton]

Yes, closing...