RESTMapper doesn't support the same

[piosz]

I created #19820 which adds to metrics api group types Pod and Node (which already exists in the default api group). Please correct me if I'm wrong but this case should be supported. Unfortunately when testing the mentioned change kubectl returns the following error:

error: unable to get RESTClient for resource 'nodes'

The problem is with MultiRESTMapper which iterates over mappers in arbitrary order.

Assigning @lavalamp for triage.

cc @kubernetes/goog-csi

[lavalamp]

Yes, I think this is a bug. We should use a deterministic search order and it should search "/v1" before other groups.

[lavalamp]

@caesarxuchao @krousey

[piosz]

It will be just a temporary fix, until someone wants to have 2 types with the same name within two different API groups which different than /v1. Does anyone from CSI team plan to work on it? If not I can do it.

[lavalamp]

We'd be happy for you to do it :)

[bgrant0607]

cc @madhusudancs

[bgrant0607]

horizontalpodautoscalers and jobs will have the same problem once they move to new API groups.

Was encountered as part of #20501

cc @janetkuo @erictune