kubectl api-resources命令就是先获取所有API版本信息，然后对每一个API版本调用接口获取该版本下的所有API资源类型
$ kubectl -v=8 api-resources 5077 loader.go:375] Config loaded from file: /root/.kube/config I1211 15:19:47.593450 15077 round_trippers.go:420] GET https://127.0.0.1:6443/api?timeout=32s I1211 15:19:47.602273 15077 request.go:1068] Response Body: {"kind":"APIVersions","versions":["v1"],"serverAddressByClientCIDRs":[{"clientCIDR":"0.0.0.0/0","serverAddress":"x.x.x.x:6443"}]} I1211 15:19:47.606279 15077 round_trippers.go:420] GET https://127.0.0.1:6443/apis?timeout=32s I1211 15:19:47.610333 15077 request.go:1068] Response Body: {"kind":"APIGroupList","apiVersion":"v1","groups":[{"name":"apiregistration.k8s.io","versions":[{"groupVersion":"apiregistration.k8s.io/v1","version":"v1"},{"groupVersion":"apiregistration.k8s.io/v1beta1","version":"v1beta1"}],"preferredVersion":{"groupVersion":"apiregistration.k8s.io/v1","version":"v1"}},{"name":"extensions","versions":[{"groupVersion":"extensions/v1beta1","version":"v1beta1"}],"preferredVersion":{"groupVersion":"extensions/v1beta1","version":"v1beta1"}},{"name":"apps","versions":[{"groupVersion":"apps/v1","version":"v1"}],"preferredVersion":{"groupVersion":"apps/v1","version":"v1"}},{"name":"events.k8s.io","versions":[{"groupVersion":"events.k8s.io/v1beta1","version":"v1beta1"}],"preferredVersion":{"groupVersion":"events.k8s.io/v1beta1","version":"v1beta1"}},{"name":"authentication.k8s.io","versions":[{"groupVersion":"authentication.k8s.io/v1","version":"v1"},{"groupVersion":"authentication.k8s.io/v1beta1","version":"v1beta1"}],"preferredVersion":{"groupVersion":"authentication.k8s.io/v1"," [truncated 4985 chars] I1211 15:19:47.614700 15077 round_trippers.go:420] GET https://127.0.0.1:6443/apis/batch/v1?timeout=32s I1211 15:19:47.614804 15077 round_trippers.go:420] GET https://127.0.0.1:6443/apis/authentication.k8s.io/v1?timeout=32s I1211 15:19:47.615687 15077 round_trippers.go:420] GET https://127.0.0.1:6443/apis/auth.tkestack.io/v1?timeout=32s https://127.0.0.1:6443/apis/authentication.k8s.io/v1beta1?timeout=32s I1211 15:19:47.616794 15077 round_trippers.go:420] GET https://127.0.0.1:6443/apis/coordination.k8s.io/v1?timeout=32s I1211 15:19:47.616863 15077 round_trippers.go:420] GET https://127.0.0.1:6443/apis/apps/v1?timeout=32s ... NAME SHORTNAMES APIGROUP NAMESPACED KIND bindings true Binding endpoints ep true Endpoints events ev true Event limitranges limits true LimitRange namespaces ns false Namespace nodes no false Node ... - `namingController`：检查 crd obj 中是否有命名冲突，可在 crd `.status.conditions` 中查看； - `establishingController`：检查 crd 是否处于正常状态，可在 crd `.status.conditions` 中查看； - `nonStructuralSchemaController`：检查 crd obj 结构是否正常，可在 crd `.status.conditions` 中查看； - `apiApprovalController`：检查 crd 是否遵循 Kubernetes API 声明策略，可在 crd `.status.conditions` 中查看； - `finalizingController`：类似于 finalizes 的功能，与 CRs 的删除有关；
总结CR CRUD APIServer处理逻辑如下：
createAPIExtensionsServer=>NewCustomResourceDefinitionHandler=>crdHandler=>注册CR CRUD API接口：
// New returns a new instance of CustomResourceDefinitions from the given config. func (c completedConfig) New(delegationTarget genericapiserver.DelegationTarget) (*CustomResourceDefinitions, error) { ... crdHandler, err := NewCustomResourceDefinitionHandler( versionDiscoveryHandler, groupDiscoveryHandler, s.Informers.Apiextensions().V1().CustomResourceDefinitions(), delegateHandler, c.ExtraConfig.CRDRESTOptionsGetter, c.GenericConfig.AdmissionControl, establishingController, c.ExtraConfig.ServiceResolver, c.ExtraConfig.AuthResolverWrapper, c.ExtraConfig.MasterCount, s.GenericAPIServer.Authorizer, c.GenericConfig.RequestTimeout, time.Duration(c.GenericConfig.MinRequestTimeout)*time.Second, apiGroupInfo.StaticOpenAPISpec, c.GenericConfig.MaxRequestBodyBytes, ) if err != nil { return nil, err } s.GenericAPIServer.Handler.NonGoRestfulMux.Handle("/apis", crdHandler) s.GenericAPIServer.Handler.NonGoRestfulMux.HandlePrefix("/apis/", crdHandler) ... return s, nil }
crdHandler处理逻辑如下：
解析req(GET /apis/duyanghao.example.com/v1/namespaces/default/students)，根据请求路径中的group(duyanghao.example.com)，version(v1)，以及resource字段(students)获取对应CRD内容(crd, err := r.crdLister.Get(crdName))