Merge pull request #63502 from liggitt/parallel-discovery

Automatic merge from submit-queue (batch tested with PRs 62354, 62934, 63502). If you want to cherry-pick this change to another branch, please follow the instructions <a href="https://github.com/kubernetes/community/blob/master/contributors/devel/cherry-picks.md">here</a>.

Run resource discovery in parallel

best viewed ignoring whitespace (https://github.com/kubernetes/kubernetes/pull/63502/files?w=1)

on high-latency connections, serializing resource discovery requests across group versions can take significant amounts of time. this parallelizes the network request portion of the discovery call

xref #63368

```release-note
NONE
```

Kubernetes-commit: 234939dced42952045fc2a42b74a805affcff965

discovery/discovery_client.go

@@ -22,6 +22,7 @@ import (
 	"net/url"
 	"sort"
 	"strings"
+	"sync"
 	"time"
 
 	"github.com/golang/protobuf/proto"
@@ -32,6 +33,7 @@ import (
 	"k8s.io/apimachinery/pkg/runtime"
 	"k8s.io/apimachinery/pkg/runtime/schema"
 	"k8s.io/apimachinery/pkg/runtime/serializer"
+	utilruntime "k8s.io/apimachinery/pkg/util/runtime"
 	"k8s.io/apimachinery/pkg/version"
 	"k8s.io/client-go/kubernetes/scheme"
 	restclient "k8s.io/client-go/rest"
@@ -191,33 +193,7 @@ func (d *DiscoveryClient) ServerResourcesForGroupVersion(groupVersion string) (r
 
 // serverResources returns the supported resources for all groups and versions.
 func (d *DiscoveryClient) serverResources() ([]*metav1.APIResourceList, error) {
-	apiGroups, err := d.ServerGroups()
-	if err != nil {
-		return nil, err
-	}
-
-	result := []*metav1.APIResourceList{}
-	failedGroups := make(map[schema.GroupVersion]error)
-
-	for _, apiGroup := range apiGroups.Groups {
-		for _, version := range apiGroup.Versions {
-			gv := schema.GroupVersion{Group: apiGroup.Name, Version: version.Version}
-			resources, err := d.ServerResourcesForGroupVersion(version.GroupVersion)
-			if err != nil {
-				// TODO: maybe restrict this to NotFound errors
-				failedGroups[gv] = err
-				continue
-			}
-
-			result = append(result, resources)
-		}
-	}
-
-	if len(failedGroups) == 0 {
-		return result, nil
-	}
-
-	return result, &ErrGroupDiscoveryFailed{Groups: failedGroups}
+	return ServerResources(d)
 }
 
 // ServerResources returns the supported resources for all groups and versions.
@@ -253,6 +229,33 @@ func (d *DiscoveryClient) serverPreferredResources() ([]*metav1.APIResourceList,
 	return ServerPreferredResources(d)
 }
 
+// ServerResources uses the provided discovery interface to look up supported resources for all groups and versions.
+func ServerResources(d DiscoveryInterface) ([]*metav1.APIResourceList, error) {
+	apiGroups, err := d.ServerGroups()
+	if err != nil {
+		return nil, err
+	}
+
+	groupVersionResources, failedGroups := fetchGroupVersionResources(d, apiGroups)
+
+	// order results by group/version discovery order
+	result := []*metav1.APIResourceList{}
+	for _, apiGroup := range apiGroups.Groups {
+		for _, version := range apiGroup.Versions {
+			gv := schema.GroupVersion{Group: apiGroup.Name, Version: version.Version}
+			if resources, ok := groupVersionResources[gv]; ok {
+				result = append(result, resources)
+			}
+		}
+	}
+
+	if len(failedGroups) == 0 {
+		return result, nil
+	}
+
+	return result, &ErrGroupDiscoveryFailed{Groups: failedGroups}
+}
+
 // ServerPreferredResources uses the provided discovery interface to look up preferred resources
 func ServerPreferredResources(d DiscoveryInterface) ([]*metav1.APIResourceList, error) {
 	serverGroupList, err := d.ServerGroups()
@@ -260,9 +263,9 @@ func ServerPreferredResources(d DiscoveryInterface) ([]*metav1.APIResourceList,
 		return nil, err
 	}
 
-	result := []*metav1.APIResourceList{}
-	failedGroups := make(map[schema.GroupVersion]error)
+	groupVersionResources, failedGroups := fetchGroupVersionResources(d, serverGroupList)
 
+	result := []*metav1.APIResourceList{}
 	grVersions := map[schema.GroupResource]string{}                         // selected version of a GroupResource
 	grApiResources := map[schema.GroupResource]*metav1.APIResource{}        // selected APIResource for a GroupResource
 	gvApiResourceLists := map[schema.GroupVersion]*metav1.APIResourceList{} // blueprint for a APIResourceList for later grouping
@@ -270,10 +273,9 @@ func ServerPreferredResources(d DiscoveryInterface) ([]*metav1.APIResourceList,
 	for _, apiGroup := range serverGroupList.Groups {
 		for _, version := range apiGroup.Versions {
 			groupVersion := schema.GroupVersion{Group: apiGroup.Name, Version: version.Version}
-			apiResourceList, err := d.ServerResourcesForGroupVersion(version.GroupVersion)
-			if err != nil {
-				// TODO: maybe restrict this to NotFound errors
-				failedGroups[groupVersion] = err
+
+			apiResourceList, ok := groupVersionResources[groupVersion]
+			if !ok {
 				continue
 			}
 
@@ -315,6 +317,41 @@ func ServerPreferredResources(d DiscoveryInterface) ([]*metav1.APIResourceList,
 	return result, &ErrGroupDiscoveryFailed{Groups: failedGroups}
 }
 
+// fetchServerResourcesForGroupVersions uses the discovery client to fetch the resources for the specified groups in parallel
+func fetchGroupVersionResources(d DiscoveryInterface, apiGroups *metav1.APIGroupList) (map[schema.GroupVersion]*metav1.APIResourceList, map[schema.GroupVersion]error) {
+	groupVersionResources := make(map[schema.GroupVersion]*metav1.APIResourceList)
+	failedGroups := make(map[schema.GroupVersion]error)
+
+	wg := &sync.WaitGroup{}
+	resultLock := &sync.Mutex{}
+	for _, apiGroup := range apiGroups.Groups {
+		for _, version := range apiGroup.Versions {
+			groupVersion := schema.GroupVersion{Group: apiGroup.Name, Version: version.Version}
+			wg.Add(1)
+			go func() {
+				defer wg.Done()
+				defer utilruntime.HandleCrash()
+
+				apiResourceList, err := d.ServerResourcesForGroupVersion(groupVersion.String())
+
+				// lock to record results
+				resultLock.Lock()
+				defer resultLock.Unlock()
+
+				if err != nil {
+					// TODO: maybe restrict this to NotFound errors
+					failedGroups[groupVersion] = err
+				} else {
+					groupVersionResources[groupVersion] = apiResourceList
+				}
+			}()
+		}
+	}
+	wg.Wait()
+
+	return groupVersionResources, failedGroups
+}
+
 // ServerPreferredResources returns the supported resources with the version preferred by the
 // server.
 func (d *DiscoveryClient) ServerPreferredResources() ([]*metav1.APIResourceList, error) {

discovery/discovery_client_test.go

@@ -32,6 +32,7 @@ import (
 
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"k8s.io/apimachinery/pkg/runtime/schema"
+	"k8s.io/apimachinery/pkg/util/diff"
 	"k8s.io/apimachinery/pkg/util/sets"
 	"k8s.io/apimachinery/pkg/version"
 	restclient "k8s.io/client-go/rest"
@@ -204,6 +205,14 @@ func TestGetServerResources(t *testing.T) {
 			{Name: "jobs", Namespaced: true, Kind: "Job"},
 		},
 	}
+	beta2 := metav1.APIResourceList{
+		GroupVersion: "extensions/v1beta2",
+		APIResources: []metav1.APIResource{
+			{Name: "deployments", Namespaced: true, Kind: "Deployment"},
+			{Name: "ingresses", Namespaced: true, Kind: "Ingress"},
+			{Name: "jobs", Namespaced: true, Kind: "Job"},
+		},
+	}
 	tests := []struct {
 		resourcesList *metav1.APIResourceList
 		path          string
@@ -236,6 +245,8 @@ func TestGetServerResources(t *testing.T) {
 			list = &stable
 		case "/apis/extensions/v1beta1":
 			list = &beta
+		case "/apis/extensions/v1beta2":
+			list = &beta2
 		case "/api":
 			list = &metav1.APIVersions{
 				Versions: []string{
@@ -246,8 +257,10 @@ func TestGetServerResources(t *testing.T) {
 			list = &metav1.APIGroupList{
 				Groups: []metav1.APIGroup{
 					{
+						Name: "extensions",
 						Versions: []metav1.GroupVersionForDiscovery{
-							{GroupVersion: "extensions/v1beta1"},
+							{GroupVersion: "extensions/v1beta1", Version: "v1beta1"},
+							{GroupVersion: "extensions/v1beta2", Version: "v1beta2"},
 						},
 					},
 				},
@@ -289,11 +302,10 @@ func TestGetServerResources(t *testing.T) {
 	if err != nil {
 		t.Errorf("unexpected error: %v", err)
 	}
-	serverGroupVersions := sets.NewString(groupVersions(serverResources)...)
-	for _, api := range []string{"v1", "extensions/v1beta1"} {
-		if !serverGroupVersions.Has(api) {
-			t.Errorf("missing expected api %q in %v", api, serverResources)
-		}
+	serverGroupVersions := groupVersions(serverResources)
+	expectedGroupVersions := []string{"v1", "extensions/v1beta1", "extensions/v1beta2"}
+	if !reflect.DeepEqual(expectedGroupVersions, serverGroupVersions) {
+		t.Errorf("unexpected group versions: %v", diff.ObjectReflectDiff(expectedGroupVersions, serverGroupVersions))
 	}
 }
 
@@ -639,7 +651,7 @@ func TestServerPreferredResourcesRetries(t *testing.T) {
 						{
 							Name: "extensions",
 							Versions: []metav1.GroupVersionForDiscovery{
-								{GroupVersion: "extensions/v1beta1"},
+								{GroupVersion: "extensions/v1beta1", Version: "v1beta1"},
 							},
 							PreferredVersion: metav1.GroupVersionForDiscovery{
 								GroupVersion: "extensions/v1beta1",