ApiGroup::recommended_kind returns None while I expected Some(_)

[xMAC94x]

Current and expected behavior

I would expect for ApiGroup::recommended_kind to return a kind when one exists. And only return None when no viable kind exist.

Imagine 2 CRD deployed KindA and KindB. both in the same group example.com
KindA has versions v1 and v2.
KindB only supports v1.

Now running recommended_kind for KindB will result in the following.

The code of https://github.com/kube-rs/kube/blob/0.85.0/kube-client/src/discovery/apigroup.rs#L301 will first detect the preferable version, which is v2 and now it does not find any kind supporting this.

So the coding asserts that all Kinds in a Group support the same version.
I would either expect a change in that behavior and fall back to v1. or at least add a comment to the function so that its clear that it might return None, even if there working versions available, when another kind in a similar group has a newer version. And link to the resources_by_stability function.

Possible solution

I am not 100% sure if this is a documentation bug or a actual behavior bug.
In case of a documentation bug. Add the documentation to make people aware of this constellation.

Otherwise, we need to check other versions, if the loop finished and the return inside wasnt hit.

Additional context

No response

Environment

 [
  (ApiResource { group: "example.com", version: "v1", api_version: "example.com/v1", kind: "KindA", plural: "KindAs" }, ApiCapabilities { scope: Namespaced, subresources: [...], operations: [...] }), 
  (ApiResource { group: "example.com", version: "v2", api_version: "example.com/v2", kind: "KindA", plural: "KindAs" }, ApiCapabilities { scope: Namespaced, subresources: [...], operations: [...] }), 
  (ApiResource { group: "example.com", version: "v1", api_version: "example.com/v1", kind: "KindB", plural: "KindBs" }, ApiCapabilities { scope: Namespaced, subresources: [...], operations: [...] }), 
 ]

Client Version: v1.27.4
Kustomize Version: v5.0.1
Server Version: v1.25.10

Configuration and features

k8s-openapi = { version = "0.19", features = ["v1_27"] }
kube = { version = "0.85", features = ["runtime", "client"] }

Affected crates

No response

Would you like to work on fixing this bug?

maybe

[clux]

Thanks for reporting / writing this down. This is definitely one of those strange footguns that everyone is confused by. It still feels like a documentation issue to me, because it kind falls out of the upstream api (that returns APIGroupList containing APIGroups) that a preferred_version is a group-wide concept (and so you should probably version resources in a group consistently).

This is not at all intuitive though. It kind of also discourages version changes imo.

It would at the very least make sense to add a paragraph or two about it under our ApiGroup or the main methods where people are likely to read about preferred versions.