Support managing snapshot policies

[swoehrl-mw]

Discussed in https://github.com/opensearch-project/opensearch-k8s-operator/discussions/796

The operator already supports managing snapshot repositories. A step further would be to add a custom resource and reconciler logic (similar to ISMPolicies) to also manage snapshot policies via the operator.

[prudhvigodithi]

[Triage] Thanks @swoehrl-mw so the idea is to have a CRD to configure a snapshot policy ? @bbarani

[swoehrl-mw]

@prudhvigodithi

so the idea is to have a CRD to configure a snapshot policy ?

Exactly. We can introduce a new CRD for that and add a reconciler to the operator to handle it.

[cthtrifork]

Wouldn't creating a ISMPolcy with a snapshot: https://opensearch.org/docs/latest/im-plugin/ism/policies/#snapshot archieve the same?

[AdaptiveStep]

Hmm. What opensearch needs is a way to document the api in a systemic way using openAPI/swagger style. That would simplify the usage of the opensearch api a lot for future operator developement. (That is atleast the path elastic took)

opensearch needs an api like this: https://www.elastic.co/docs/api/doc/kibana/v8

This would also make sure that the api- documentation is automatically generated and also up-to-date. I can't believe we don't have something like this yet..