Merge branch 'patch-58' into 'master'

Documentation change redis.md with an updated required Redis version

Closes #196699

See merge request gitlab-org/gitlab!23888

doc/administration/high_availability/redis.md

@@ -8,8 +8,10 @@ type: reference
 
 The following are the requirements for providing your own Redis instance:
 
-- Redis version 2.8 or higher. Version 3.2 or higher is recommend as this is
-  what ships with the GitLab Omnibus package.
+- GitLab 12.0 and later requires Redis version 3.2 or higher. Version 3.2 or higher is recommend as this is
+  what ships with the GitLab Omnibus package. Older Redis versions do not
+  support an optional count argument to SPOP which is now required for
+  [Merge Trains](../../ci/merge_request_pipelines/pipelines_for_merged_results/merge_trains/index.md).
 - Standalone Redis or Redis high availability with Sentinel are supported. Redis
   Cluster is not supported.
 - Managed Redis from cloud providers such as AWS Elasticache will work. If these

doc/ci/merge_request_pipelines/pipelines_for_merged_results/merge_trains/index.md

@@ -30,6 +30,7 @@ Pipelines invalidated through failures are immediately canceled and requeued.
 
 Merge trains have the following requirements and limitations:
 
+- GitLab 12.0 and later requires [Redis](https://redis.io/) 3.2 or higher to run Merge Trains.
 - This feature requires that
   [pipelines for merged results](../index.md#pipelines-for-merged-results-premium) are
   **configured properly**.