Discovery client and aggregator downloader use /openapi/v2 endpoint

staging/src/k8s.io/client-go/discovery/discovery_client.go

@@ -36,8 +36,12 @@ import (
 	restclient "k8s.io/client-go/rest"
 )
 
-// defaultRetries is the number of times a resource discovery is repeated if an api group disappears on the fly (e.g. ThirdPartyResources).
-const defaultRetries = 2
+const (
+	// defaultRetries is the number of times a resource discovery is repeated if an api group disappears on the fly (e.g. ThirdPartyResources).
+	defaultRetries = 2
+	// protobuf mime type
+	mimePb = "application/com.github.proto-openapi.spec.v2@v1.0+protobuf"
+)
 
 // DiscoveryInterface holds the methods that discover server-supported API groups,
 // versions and resources.
@@ -329,9 +333,18 @@ func (d *DiscoveryClient) ServerVersion() (*version.Info, error) {
 
 // OpenAPISchema fetches the open api schema using a rest client and parses the proto.
 func (d *DiscoveryClient) OpenAPISchema() (*openapi_v2.Document, error) {
-	data, err := d.restClient.Get().AbsPath("/swagger-2.0.0.pb-v1").Do().Raw()
+	data, err := d.restClient.Get().AbsPath("/openapi/v2").SetHeader("Accept", mimePb).Do().Raw()
 	if err != nil {
-		return nil, err
+		if errors.IsForbidden(err) || errors.IsNotFound(err) {
+			// single endpoint not found/registered in old server, try to fetch old endpoint
+			// TODO(roycaihw): remove this in 1.11
+			data, err = d.restClient.Get().AbsPath("/swagger-2.0.0.pb-v1").Do().Raw()
+			if err != nil {
+				return nil, err
+			}
+		} else {
+			return nil, err
+		}
 	}
 	document := &openapi_v2.Document{}
 	err = proto.Unmarshal(data, document)

staging/src/k8s.io/client-go/discovery/discovery_client_test.go

@@ -326,9 +326,14 @@ var returnedOpenAPI = openapi_v2.Document{
 	},
 }
 
-func openapiSchemaFakeServer() (*httptest.Server, error) {
+func openapiSchemaDeprecatedFakeServer() (*httptest.Server, error) {
 	var sErr error
 	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, req *http.Request) {
+		// old server returns 403 on new endpoint request
+		if req.URL.Path == "/openapi/v2" {
+			w.WriteHeader(http.StatusForbidden)
+			return
+		}
 		if req.URL.Path != "/swagger-2.0.0.pb-v1" {
 			sErr = fmt.Errorf("Unexpected url %v", req.URL)
 		}
@@ -349,6 +354,33 @@ func openapiSchemaFakeServer() (*httptest.Server, error) {
 	return server, sErr
 }
 
+func openapiSchemaFakeServer() (*httptest.Server, error) {
+	var sErr error
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, req *http.Request) {
+		if req.URL.Path != "/openapi/v2" {
+			sErr = fmt.Errorf("Unexpected url %v", req.URL)
+		}
+		if req.Method != "GET" {
+			sErr = fmt.Errorf("Unexpected method %v", req.Method)
+		}
+		decipherableFormat := req.Header.Get("Accept")
+		if decipherableFormat != "application/com.github.proto-openapi.spec.v2@v1.0+protobuf" {
+			sErr = fmt.Errorf("Unexpected accept mime type %v", decipherableFormat)
+		}
+
+		mime.AddExtensionType(".pb-v1", "application/com.github.googleapis.gnostic.OpenAPIv2@68f4ded+protobuf")
+
+		output, err := proto.Marshal(&returnedOpenAPI)
+		if err != nil {
+			sErr = err
+			return
+		}
+		w.WriteHeader(http.StatusOK)
+		w.Write(output)
+	}))
+	return server, sErr
+}
+
 func TestGetOpenAPISchema(t *testing.T) {
 	server, err := openapiSchemaFakeServer()
 	if err != nil {
@@ -366,6 +398,23 @@ func TestGetOpenAPISchema(t *testing.T) {
 	}
 }
 
+func TestGetOpenAPISchemaFallback(t *testing.T) {
+	server, err := openapiSchemaDeprecatedFakeServer()
+	if err != nil {
+		t.Errorf("unexpected error starting fake server: %v", err)
+	}
+	defer server.Close()
+
+	client := NewDiscoveryClientForConfigOrDie(&restclient.Config{Host: server.URL})
+	got, err := client.OpenAPISchema()
+	if err != nil {
+		t.Fatalf("unexpected error getting openapi: %v", err)
+	}
+	if e, a := returnedOpenAPI, *got; !reflect.DeepEqual(e, a) {
+		t.Errorf("expected %v, got %v", e, a)
+	}
+}
+
 func TestServerPreferredResources(t *testing.T) {
 	stable := metav1.APIResourceList{
 		GroupVersion: "v1",

staging/src/k8s.io/kube-aggregator/pkg/controllers/openapi/aggregator_test.go

@@ -93,6 +93,32 @@ func (h handlerTest) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 	w.Write(h.data)
 }
 
+type handlerDeprecatedTest struct {
+	etag string
+	data []byte
+}
+
+var _ http.Handler = handlerDeprecatedTest{}
+
+func (h handlerDeprecatedTest) ServeHTTP(w http.ResponseWriter, r *http.Request) {
+	// old server returns 403 on new endpoint
+	if r.URL.Path == "/openapi/v2" {
+		w.WriteHeader(http.StatusForbidden)
+		return
+	}
+	if len(h.etag) > 0 {
+		w.Header().Add("Etag", h.etag)
+	}
+	ifNoneMatches := r.Header["If-None-Match"]
+	for _, match := range ifNoneMatches {
+		if match == h.etag {
+			w.WriteHeader(http.StatusNotModified)
+			return
+		}
+	}
+	w.Write(h.data)
+}
+
 func assertDownloadedSpec(actualSpec *spec.Swagger, actualEtag string, err error,
 	expectedSpecID string, expectedEtag string) error {
 	if err != nil {
@@ -132,4 +158,9 @@ func TestDownloadOpenAPISpec(t *testing.T) {
 	actualSpec, actualEtag, _, err = s.Download(
 		handlerTest{data: []byte("{\"id\": \"test\"}"), etag: "etag_test1"}, "etag_test2")
 	assert.NoError(t, assertDownloadedSpec(actualSpec, actualEtag, err, "test", "etag_test1"))
+
+	// Test old server fallback path
+	actualSpec, actualEtag, _, err = s.Download(handlerDeprecatedTest{data: []byte("{\"id\": \"test\"}")}, "")
+	assert.NoError(t, assertDownloadedSpec(actualSpec, actualEtag, err, "test", "\"6E8F849B434D4B98A569B9D7718876E9-356ECAB19D7FBE1336BABB1E70F8F3025050DE218BE78256BE81620681CFC9A268508E542B8B55974E17B2184BBFC8FFFAA577E51BE195D32B3CA2547818ABE4\""))
+
 }

staging/src/k8s.io/kube-aggregator/pkg/controllers/openapi/downloader.go

@@ -99,10 +99,11 @@ func (s *Downloader) Download(handler http.Handler, etag string) (returnSpec *sp
 	handler = request.WithRequestContext(handler, s.contextMapper)
 	handler = http.TimeoutHandler(handler, specDownloadTimeout, "request timed out")
 
-	req, err := http.NewRequest("GET", "/swagger.json", nil)
+	req, err := http.NewRequest("GET", "/openapi/v2", nil)
 	if err != nil {
 		return nil, "", 0, err
 	}
+	req.Header.Add("Accept", "application/json")
 
 	// Only pass eTag if it is not generated locally
 	if len(etag) > 0 && !strings.HasPrefix(etag, locallyGeneratedEtagPrefix) {
@@ -112,6 +113,23 @@ func (s *Downloader) Download(handler http.Handler, etag string) (returnSpec *sp
 	writer := newInMemoryResponseWriter()
 	handler.ServeHTTP(writer, req)
 
+	// single endpoint not found/registered in old server, try to fetch old endpoint
+	// TODO(roycaihw): remove this in 1.11
+	if writer.respCode == http.StatusForbidden || writer.respCode == http.StatusNotFound {
+		req, err = http.NewRequest("GET", "/swagger.json", nil)
+		if err != nil {
+			return nil, "", 0, err
+		}
+
+		// Only pass eTag if it is not generated locally
+		if len(etag) > 0 && !strings.HasPrefix(etag, locallyGeneratedEtagPrefix) {
+			req.Header.Add("If-None-Match", etag)
+		}
+
+		writer = newInMemoryResponseWriter()
+		handler.ServeHTTP(writer, req)
+	}
+
 	switch writer.respCode {
 	case http.StatusNotModified:
 		if len(etag) == 0 {