Update the ILM UI to include the ability to wait for snapshot

[matt-davis-elastic]

ILM is adding a new action in the delete phase that allows ILM to wait for the specified snapshot policy to complete. Can we add something in the UI on the delete phase to allow someone to include the action to wait for a snapshot policy?

@jethr0null let me know if you need any other information.

[snide]

Hello @matt-davis-elastic. I think you might have dropped this issue in the wrong repo. The covers the React UI framework (Elastic UI Framework) and doesn't cover the Elasticsearch UI. For those issues, I think you want to make them in Kibana, likely using the Elasticsearch UI label. https://github.com/elastic/kibana/issues?q=is%3Aopen+is%3Aissue+label%3A%22Team%3AElasticsearch+UI%22

[jethr0null]

cc @elastic/es-ui

[jethr0null]

@cjcenizal, @matt-davis-elastic and I chatted about this and he is planning on adding some additional detail to this issue when he has a chance.

[cjcenizal]

For reference, here's the ES PR that introduced the change to the API: elastic/elasticsearch#45067

[cjcenizal]

This change adds a "snapshot" action to the delete phase (Snapshot action docs). Here's an example of a policy that uses this action to wait until the slm-policy-name SLM policy has taken a snapshot before proceeding to delete the index:

PUT _ilm/policy/my_policy
{
  "policy": {
    "phases": {
      "delete": {
        "actions": {
          "wait_for_snapshot" : {
            "policy": "slm-policy-name"
          }
        }
      }
    }
  }
}

We can surface this in the UI with a single-selection combobox that's populated with the user's SLM policies. A nice enhancement would be a preview that shows up below the combobox that shows you the crucial details of the policy you've selected (and maybe a deep-link into Snapshot Restore).

[matt-davis-elastic]

Yes, thanks, CJ. Somehow I lost track of this ticket. I think a single-selection combobox would solve this.

[cjcenizal]

Addressed by #68505