Fallback to legacy discovery on a wider range of conditions in aggregator

Kubernetes-commit: 57b27fd3cd11cb5f2515c7ac5f67f612998fb368

discovery/discovery_client.go

@@ -68,6 +68,9 @@ const (
 	acceptDiscoveryFormats = AcceptV2Beta1 + "," + AcceptV1
 )
 
+// Aggregated discovery content-type GVK.
+var v2Beta1GVK = schema.GroupVersionKind{Group: "apidiscovery.k8s.io", Version: "v2beta1", Kind: "APIGroupDiscoveryList"}
+
 // DiscoveryInterface holds the methods that discover server-supported API groups,
 // versions and resources.
 type DiscoveryInterface interface {
@@ -261,16 +264,15 @@ func (d *DiscoveryClient) downloadLegacy() (
 	}
 
 	var resourcesByGV map[schema.GroupVersion]*metav1.APIResourceList
-	// Switch on content-type server responded with: aggregated or unaggregated.
+	// Based on the content-type server responded with: aggregated or unaggregated.
-	switch {
+	if isGVK, _ := ContentTypeIsGVK(responseContentType, v2Beta1GVK); isGVK {
-	case isV2Beta1ContentType(responseContentType):
 		var aggregatedDiscovery apidiscovery.APIGroupDiscoveryList
 		err = json.Unmarshal(body, &aggregatedDiscovery)
 		if err != nil {
 			return nil, nil, nil, err
 		}
 		apiGroupList, resourcesByGV, failedGVs = SplitGroupsAndResources(aggregatedDiscovery)
-	default:
+	} else {
 		// Default is unaggregated discovery v1.
 		var v metav1.APIVersions
 		err = json.Unmarshal(body, &v)
@@ -314,16 +316,15 @@ func (d *DiscoveryClient) downloadAPIs() (
 	apiGroupList := &metav1.APIGroupList{}
 	failedGVs := map[schema.GroupVersion]error{}
 	var resourcesByGV map[schema.GroupVersion]*metav1.APIResourceList
-	// Switch on content-type server responded with: aggregated or unaggregated.
+	// Based on the content-type server responded with: aggregated or unaggregated.
-	switch {
+	if isGVK, _ := ContentTypeIsGVK(responseContentType, v2Beta1GVK); isGVK {
-	case isV2Beta1ContentType(responseContentType):
 		var aggregatedDiscovery apidiscovery.APIGroupDiscoveryList
 		err = json.Unmarshal(body, &aggregatedDiscovery)
 		if err != nil {
 			return nil, nil, nil, err
 		}
 		apiGroupList, resourcesByGV, failedGVs = SplitGroupsAndResources(aggregatedDiscovery)
-	default:
+	} else {
 		// Default is unaggregated discovery v1.
 		err = json.Unmarshal(body, apiGroupList)
 		if err != nil {
@@ -334,26 +335,29 @@ func (d *DiscoveryClient) downloadAPIs() (
 	return apiGroupList, resourcesByGV, failedGVs, nil
 }
 
-// isV2Beta1ContentType checks of the content-type string is both
+// ContentTypeIsGVK checks of the content-type string is both
-// "application/json" and contains the v2beta1 content-type params.
+// "application/json" and matches the provided GVK. An error
+// is returned if the content type string is malformed.
 // NOTE: This function is resilient to the ordering of the
 // content-type parameters, as well as parameters added by
 // intermediaries such as proxies or gateways. Examples:
 //
-//	"application/json; g=apidiscovery.k8s.io;v=v2beta1;as=APIGroupDiscoveryList" = true
+//	("application/json; g=apidiscovery.k8s.io;v=v2beta1;as=APIGroupDiscoveryList", {apidiscovery.k8s.io, v2beta1, APIGroupDiscoveryList}) = (true, nil)
-//	"application/json; as=APIGroupDiscoveryList;v=v2beta1;g=apidiscovery.k8s.io" = true
+//	("application/json; as=APIGroupDiscoveryList;v=v2beta1;g=apidiscovery.k8s.io", {apidiscovery.k8s.io, v2beta1, APIGroupDiscoveryList}) = (true, nil)
-//	"application/json; as=APIGroupDiscoveryList;v=v2beta1;g=apidiscovery.k8s.io;charset=utf-8" = true
+//	("application/json; as=APIGroupDiscoveryList;v=v2beta1;g=apidiscovery.k8s.io;charset=utf-8", {apidiscovery.k8s.io, v2beta1, APIGroupDiscoveryList}) = (true, nil)
-//	"application/json" = false
+//	("application/json", any GVK) = (false, nil)
-//	"application/json; charset=UTF-8" = false
+//	("application/json; charset=UTF-8", any GVK) = (false, nil)
-func isV2Beta1ContentType(contentType string) bool {
+//	("malformed content type string", any GVK) = (false, error)
+func ContentTypeIsGVK(contentType string, gvk schema.GroupVersionKind) (bool, error) {
 	base, params, err := mime.ParseMediaType(contentType)
 	if err != nil {
-		return false
+		return false, err
 	}
-	return runtime.ContentTypeJSON == base &&
+	gvkMatch := runtime.ContentTypeJSON == base &&
-		params["g"] == "apidiscovery.k8s.io" &&
+		params["g"] == gvk.Group &&
-		params["v"] == "v2beta1" &&
+		params["v"] == gvk.Version &&
-		params["as"] == "APIGroupDiscoveryList"
+		params["as"] == gvk.Kind
+	return gvkMatch, nil
 }
 
 // ServerGroups returns the supported groups, with information like supported versions and the

discovery/discovery_client_test.go

@@ -2762,54 +2762,76 @@ func TestAggregatedServerPreferredResources(t *testing.T) {
 }
 
 func TestDiscoveryContentTypeVersion(t *testing.T) {
+	v2beta1 := schema.GroupVersionKind{Group: "apidiscovery.k8s.io", Version: "v2beta1", Kind: "APIGroupDiscoveryList"}
 	tests := []struct {
 		contentType string
-		isV2Beta1   bool
+		gvk         schema.GroupVersionKind
+		match       bool
+		expectErr   bool
 	}{
 		{
 			contentType: "application/json; g=apidiscovery.k8s.io;v=v2beta1;as=APIGroupDiscoveryList",
-			isV2Beta1:   true,
+			gvk:         v2beta1,
+			match:       true,
+			expectErr:   false,
 		},
 		{
 			// content-type parameters are not in correct order, but comparison ignores order.
 			contentType: "application/json; v=v2beta1;as=APIGroupDiscoveryList;g=apidiscovery.k8s.io",
-			isV2Beta1:   true,
+			gvk:         v2beta1,
+			match:       true,
+			expectErr:   false,
 		},
 		{
 			// content-type parameters are not in correct order, but comparison ignores order.
 			contentType: "application/json; as=APIGroupDiscoveryList;g=apidiscovery.k8s.io;v=v2beta1",
-			isV2Beta1:   true,
+			gvk:         v2beta1,
+			match:       true,
+			expectErr:   false,
 		},
 		{
 			// Ignores extra parameter "charset=utf-8"
 			contentType: "application/json; g=apidiscovery.k8s.io;v=v2beta1;as=APIGroupDiscoveryList;charset=utf-8",
-			isV2Beta1:   true,
+			gvk:         v2beta1,
+			match:       true,
+			expectErr:   false,
 		},
 		{
 			contentType: "application/json",
-			isV2Beta1:   false,
+			gvk:         v2beta1,
+			match:       false,
+			expectErr:   false,
 		},
 		{
 			contentType: "application/json; charset=UTF-8",
-			isV2Beta1:   false,
+			gvk:         v2beta1,
+			match:       false,
+			expectErr:   false,
 		},
 		{
 			contentType: "text/json",
-			isV2Beta1:   false,
+			gvk:         v2beta1,
+			match:       false,
+			expectErr:   false,
 		},
 		{
 			contentType: "text/html",
-			isV2Beta1:   false,
+			gvk:         v2beta1,
+			match:       false,
+			expectErr:   false,
 		},
 		{
 			contentType: "",
-			isV2Beta1:   false,
+			gvk:         v2beta1,
+			match:       false,
+			expectErr:   true,
 		},
 	}
 
 	for _, test := range tests {
-		isV2Beta1 := isV2Beta1ContentType(test.contentType)
+		match, err := ContentTypeIsGVK(test.contentType, test.gvk)
-		assert.Equal(t, test.isV2Beta1, isV2Beta1)
+		assert.Equal(t, test.expectErr, err != nil)
+		assert.Equal(t, test.match, match)
 	}
 }