[HLRC] Added support for CCR Get Auto Follow Pattern apis

[martijnvg]

This change also adds documentation for the Get Auto Follow Pattern API.

Relates to #33824

[elasticmachine]

Pinging @elastic/es-core-features

[hub-cap]

heh you know the HLRC PR process well now. Great work.

[codebrain]

Hi @martijnvg, this appears to be a breaking change in the response format between versions 6.5 and 6.6:

Examples:

6.5:

{
  "my_auto_follow_pattern" :
  {
    "remote_cluster" : "remote_cluster",
    "leader_index_patterns" :
    [
      "leader_index*"
    ],
    "follow_index_pattern" : "{{leader_index}}-follower"
  }
}

6.6:

{
  "patterns": [
    {
      "name": "my_auto_follow_pattern",
      "pattern": {
        "remote_cluster" : "remote_cluster",
        "leader_index_patterns" :
        [
          "leader_index*"
        ],
        "follow_index_pattern" : "{{leader_index}}-follower"
      }
    }
  ]
}

We have a mechanism by which we can workaround this breaking change in the .NET client (a custom derserializer), but I wanted to check the reasoning behind this change? Are there any intentions to add sibling json nodes to the "patterns" node?

Thanks!

[martijnvg]

Hey @codebrain

This breaking change was part of #36203, which also describes the reasoning.

Are there any intentions to add sibling json nodes to the "patterns" node?

No, at the moment there are no plans for this. But this will allow us to do so in the future if needed.