base path setting on stackconfigpolicy snapshot repository

[thbkrkr]

For cloud repositories (azure, gcs, s3), ECK sets base_path to snapshots/<namespace>-<esName> and it's not possible to override it. This is problematic for example to configure a read-only repository where a user wants full control of the base_path.

cloud-on-k8s/pkg/controller/elasticsearch/filesettings/file_settings.go

Line 148 in ae88fe1

settings["base_path"] = fmt.Sprintf("snapshots/%s", suffix)

I missed the original intent that was to only add <namespace>-<esName> to the user provided base_path like it's done for location for fs repository and path for hdfs repository. But this is also a problem if the need is to fully control the base_path.

I could see 3 cases, but I'm not sure we need to deal with the third one, which makes everything more complex because we need to be able to distinguish it from the second one.

	user provided base_path	configured base_path
1) no base_path		snapshots/ns1-es1
2) full base_path	some/thing	some/thing
3) partial base_path	some/thing	some/thing/ns1-es1

[pebrc]

What would be the use case for the 3 case?

[thbkrkr]

A use-case where you want something else than snapshots as the location to write the snapshots in the bucket.

Imagine you have two environments but you are restricted to one bucket (ok, it's bizarre, but) and you want to configure a different base_path per env so you can have the same name for the clusters: snapshots-qa/ns1-es1 & snapshots-prod/ns1-es1.

Use-case 2 makes sense only for read-only repositories. For write/read repositories, you need 1 or 3.

[pebrc]

I think it is a reasonable restriction to say if you want to share the bucket that you have to live with the naming scheme we propose?

[thbkrkr]

I think so too and this is the option I finally opted into #6689.