Elasticsearch branch 7.X support

Problem to solve

Gitlab should support the last Elasticsearch version. Last Gitlab version (12.3.5-ee) doesn't support Elasticsearch branch 7 (the current stable version is v7.4, the branch 7.X is stable since April 10, 2019: Elasticsearch 7.0.0 released).

Intended users

Further details

In my company, we use the same Elasticsearch cluster to index/search data from our programs and from our Gitlab instance, this cluster has been upgraded from the 6th branch to the 7th for our program needs.

Due to the Gitlab restriction, we have to mount another Elasticsearch cluster (version 6.8) to permit the Gitlab advanced search.

Proposal

Update the Elasticsearch integration to support the 7.X branch.

Documentation

The following documentation should be updated when this feature will be available: https://docs.gitlab.com/ee/integration/elasticsearch.html

Testing

The Elasticsearch integration have to still work with the 6.X branch I think. The backward compatibility should be ensured.

What does success look like, and how can we measure that?

Gitlab can be integrated with an Elasticsearch 7.X cluster.

What is the type of buyer?

The feature should be available from starter. (Like the current Elasticsearch integration)

Links / references