Change:
}) } } <ins> func TestInvalidOpenAPIV3Document(t *testing.T) { tests := map[string]struct { spec *spec3.OpenAPI }{ "nil document correctly returns Unsupported error": { spec: nil, }, "empty document correctly returns Unsupported error": { spec: &spec3.OpenAPI{}, }, "minimal document correctly returns Unsupported error": { spec: &spec3.OpenAPI{ Version: "openapi 3.0.0", Paths:   nil, }, }, "document with empty Paths correctly returns Unsupported error": { spec: &spec3.OpenAPI{ Version: "openapi 3.0.0", Paths:   &spec3.Paths{}, }, }, } gvk := schema.GroupVersionKind{ Group:   "batch", Version: "v1", Kind:    "Job", } for tn, tc := range tests { t.Run(tn, func(t *testing.T) { verifier := &queryParamVerifierV3{ finder: NewCRDFinder(func() ([]schema.GroupKind, error) { return []schema.GroupKind{}, nil }), root:       &fakeRoot{tc.spec}, queryParam: QueryParamFieldValidation, } err := verifier.HasSupport(gvk) if err == nil { t.Errorf("Expected not supports error, but none received.") } }) } } // fakeRoot implements Root interface; manually specifies the returned OpenAPI V3 document. type fakeRoot struct { spec *spec3.OpenAPI } func (f *fakeRoot) GroupVersions() ([]schema.GroupVersion, error) { // Unused return nil, nil } // GVSpec returns hard-coded OpenAPI V3 document. func (f *fakeRoot) GVSpec(gv schema.GroupVersion) (*spec3.OpenAPI, error) { return f.spec, nil } func (f *fakeRoot) GVSpecAsMap(gv schema.GroupVersion) (map[string]interface{}, error) { // Unused return nil, nil } </ins>

Discussion:
<!-- Please use this template while reporting a bug and provide as much info as possible. Not doing so may result in your bug not being addressed in a timely manner. Thanks! If the matter is security related, please disclose it privately via --What happened: Following the example here: Everything here works when you use , but when using 1.27.1, I see the following panic: What you expected to happen: When downgrading, this works as expected: How to reproduce it (as minimally and precisely as possible): <!-- Please make sure you are able to reproduce the bug using a supported version and version skew of Kubernetes. See for which versions and are currently supported. --You will need a Kubernetes cluster with Agones installed (I'm testing on 1.25.x, as you can see above), then follow this quickstart: Anything else we need to know?: The is implemented as an API Extension, not a CRD -- which is probably where the issue lies. Looking at the line: There seems to be an assuming that there will be a under and , in - there should be some nil checks in there. Environment: Kubernetes client and server versions (use ): See above Cloud provider or hardware configuration: GKE OS (e.g: ): Linux
seems like an another edge case; Due to the server version is old and openapiv3 is returning empty?
Thanks for opening this issue /triage accepted
I'm digging into the Agones code, but I'm 99.4% sure we don't even implement openapiv3 at all for our api endpoint
Yep, confirmed -- I see a bunch of 404's in my API Extension logs for requests for
/transfer kubernetes /kind regression
/sig cli /assign
I can also work on tomorrow if Sean can not get time to look at it
If nothing else, this does also force me to publish an openapi spec for our API extension
not sure if needed to handle nils inside the schema better, or if didn't fall back to v2 correctly in the absence of v3 data
It appears to be the former, where an OpenAPI V3 document is returned without , while the code assumes this field is non-nil.
seems like that should still fall back to v2
Can we get a kubectl -v8 to see what actually happens with downloading the OpenAPI?
As requested!

Thanks for the quick response. It looks like the OpenAPI V3 document is almost completely empty The code is expecting an Open API document with . I will have a fix out shortly.
I was digging through that - I found that really interesting. We only expose an basically empty spec for the api extension. It's always "just worked", so never needed to update it. I am curious where K8s is even getting the something that it is outputting for , but that's a side note.