Kubernetes version skew support about clusternet

[DanielXLee]

Test in kind cluster version v1.18.19

# kubectl version
Client Version: version.Info{Major:"1", Minor:"21", GitVersion:"v1.21.3", GitCommit:"ca643a4d1f7bfe34773c74f79527be4afd95bf39", GitTreeState:"clean", BuildDate:"2021-07-15T21:04:39Z", GoVersion:"go1.16.6", Compiler:"gc", Platform:"linux/amd64"}
Server Version: version.Info{Major:"1", Minor:"18", GitVersion:"v1.18.19", GitCommit:"ac0cc736d0018d817c763083945e4db863168d12", GitTreeState:"clean", BuildDate:"2021-05-28T00:06:59Z", GoVersion:"go1.13.15", Compiler:"gc", Platform:"linux/amd64"}

hub error log

E0928 09:33:01.276051       1 writers.go:117] apiserver was unable to write a JSON response: http2: stream closed
E0928 09:33:01.276202       1 status.go:71] apiserver received an error that is not an metav1.Status: &errors.errorString{s:"http2: stream closed"}: http2: stream closed
I0928 09:33:01.276228       1 httplog.go:89] "HTTP" verb="GET" URI="/apis/shadow/v1alpha1" latency="884.958µs" userAgent="Go-http-client/2.0" srcIP="172.18.0.129:56774" resp=200
E0928 09:33:01.276242       1 wrap.go:54] timeout or abort while handling: GET "/apis/shadow/v1alpha1"
E0928 09:33:01.276268       1 writers.go:117] apiserver was unable to write a JSON response: http2: stream closed
I0928 09:33:01.276311       1 httplog.go:89] "HTTP" verb="GET" URI="/apis/shadow/v1alpha1" latency="699.369µs" userAgent="Go-http-client/2.0" srcIP="172.18.0.129:56774" resp=200
E0928 09:33:01.276322       1 wrap.go:54] timeout or abort while handling: GET "/apis/shadow/v1alpha1"
E0928 09:33:01.277152       1 writers.go:130] apiserver was unable to write a fallback JSON response: http: Handler timeout
E0928 09:33:01.280370       1 status.go:71] apiserver received an error that is not an metav1.Status: &errors.errorString{s:"http2: stream closed"}: http2: stream closed
E0928 09:33:01.281453       1 writers.go:130] apiserver was unable to write a fallback JSON response: http: Handler timeout

[DanielXLee]

This issue not found in k8s version v1.21.1

[dixudx]

E0928 08:40:43.222216 1 reflector.go:138] pkg/mod/k8s.io/[email protected]/tools/cache/reflector.go:167: Failed to watch *v1beta1.FlowSchema: failed to list *v1beta1.FlowSchema: the server could not find the requested resource (get flowschemas.flowcontrol.apiserver.k8s.io)

E0928 07:33:03.349992 1 reflector.go:138] pkg/mod/k8s.io/[email protected]/tools/cache/reflector.go:167: Failed to watch *v1beta1.PriorityLevelConfiguration: failed to list *v1beta1.PriorityLevelConfiguration: the server could not find the requested resource (get prioritylevelconfigurations.flowcontrol.apiserver.k8s.io)

Currently Clusternet is built with v0.21.2, which registers PriorityLevelConfiguration and FlowSchema with GroupVersion flowcontrol.apiserver.k8s.io/v1beta1. While v1.18.x registers those with GroupVersion flowcontrol.apiserver.k8s.io/v1alpha1.

[dixudx]

Add matrix on Kubernetes compatibility