OBC/COSI: Include OBC namespace in bucket metrics

[bumarcell]

Since buckets are in general created via an ObjectBucketClaim in K8s, would it be possible to include the OBC namespace in the bucket's metric?
One way is to map the bucket name so an ObjectBucket K8s object (spec.bucketName), then map the latter to an ObjectBucketClaim and extract the namespace from it.

This will be useful eg. for alerting rules, where bucket quota is defined inside the ObjectBucketClaim.

[galexrt]

It should be possible, though for bigger clusters the lookup could take longer to load all OBCs.

Though I personally would be hesitant to implement via OBCs, as COSI (kubernetes/enhancements#1383) is the future as far as I know at the moment.

[bumarcell]

You're right, but COSI is still in alpha and rook mentions it as "experimental".
How different would the implementation be? I can imagine it's not so different if it would more or less only be about porting ObjectBuckets and ObjectBucketClaims to Buckets and BucketClaims respectively.. Thus we could already have this feature in production for OBCs until COSI is production ready.

Regarding the execution time I can imagine this could be circumvented via a toggle flag :D