Graylog2-server: Remove support for Elasticsearch 2.x and add support for 6.x

[lennartkoopmann]

Let's drop support of ES v2.x and also support v6.x to avoid lagging behind for too long.

[tangyong]

looking forward to updating into elasticsearch 6.0 GA very much!

[ernestgwilsonii]

Any ETA on Elasticsearch 6x yet?
RE: _"Graylog 2.4 does not work with Elasticsearch 6.x yet!"_
REF: http://docs.graylog.org/en/2.4/pages/configuration/elasticsearch.html

[jalogisch]

@ernestgwilsonii that is placed in the Milestone for 3.0 - what will be the next version of Graylog.

[ernestgwilsonii]

@jalogisch Thanks for the update! How can folks follow along with upcoming 3.0 news, features and testing?

I currently see:
https://github.com/Graylog2/graylog2-server/milestone/57
and
The blog:
https://www.graylog.org/blog

Are those the best way to stay looped in?
Wasn't there a podcast being planned or is that random?

[jalogisch]

@ernestgwilsonii yes, that are the best ways. Consider the Podcast to be random.

[aaronjpitty]

Is there any likelihood that you'll release a 2.4.X that contains compatibility with Elasticsearch 6? We've already upgraded, and don't really want to revert that upgrade. It seems 3.0 is still a way off.

Graylog is working, but it's using graylog_deflector index and of course building up too quickly.

[joschi]

Is there any likelihood that you'll release a 2.4.X that contains compatibility with Elasticsearch 6?

No, that's entirely unlikely.

[nemmeviu]

+1

[hydrapolic]

+1

[jam49]

ES 5.6 end of life is 2019-03-11. ES 6.0 support will be needed by this time to meet internal security requirements.