Clean restmapper cache if a version is notFound

This avoids:
- Extra calls to https://host/apis/<group>/<version> when a version seen
  before and cached in apiGroups is deleted or marked as not served.
- Returnning a valid mapping for a cached version that is deleted or not
  served anymore.

pkg/client/apiutil/restmapper.go

@@ -182,23 +182,26 @@ func (m *mapper) addKnownGroupAndReload(groupName string, versions ...string) er
 		Group:              metav1.APIGroup{Name: groupName},
 		VersionedResources: make(map[string][]metav1.APIResource),
 	}
-	if _, ok := m.knownGroups[groupName]; ok {
-		groupResources = m.knownGroups[groupName]
-	}
 
 	// Update information for group resources about versioned resources.
 	// The number of API calls is equal to the number of versions: /apis/<group>/<version>.
 	groupVersionResources, err := m.fetchGroupVersionResources(groupName, versions...)
 	if err != nil {
 		return fmt.Errorf("failed to get API group resources: %w", err)
 	}
+
+	if _, ok := m.knownGroups[groupName]; ok {
+		groupResources = m.knownGroups[groupName]
+	}
+
 	for version, resources := range groupVersionResources {
 		groupResources.VersionedResources[version.Version] = resources.APIResources
 	}
 
 	// Update information for group resources about the API group by adding new versions.
 	// Ignore the versions that are already registered.
-	for _, version := range versions {
+	for groupVersion := range groupVersionResources {
+		version := groupVersion.Version
 		found := false
 		for _, v := range groupResources.Group.Versions {
 			if v.Version == version {
@@ -266,6 +269,7 @@ func (m *mapper) findAPIGroupByName(groupName string) (*metav1.APIGroup, error)
 }
 
 // fetchGroupVersionResources fetches the resources for the specified group and its versions.
+// This method might modify the cache so it needs to be called under the lock.
 func (m *mapper) fetchGroupVersionResources(groupName string, versions ...string) (map[schema.GroupVersion]*metav1.APIResourceList, error) {
 	groupVersionResources := make(map[schema.GroupVersion]*metav1.APIResourceList)
 	failedGroups := make(map[schema.GroupVersion]error)
@@ -274,9 +278,15 @@ func (m *mapper) fetchGroupVersionResources(groupName string, versions ...string
 		groupVersion := schema.GroupVersion{Group: groupName, Version: version}
 
 		apiResourceList, err := m.client.ServerResourcesForGroupVersion(groupVersion.String())
-		if err != nil && !apierrors.IsNotFound(err) {
+		if apierrors.IsNotFound(err) && m.isGroupVersionCached(groupVersion) {
+			// If the version is not found, we remove the group from the cache
+			// so it gets refreshed on the next call.
+			delete(m.apiGroups, groupName)
+			delete(m.knownGroups, groupName)
+		} else if err != nil {
 			failedGroups[groupVersion] = err
 		}
+
 		if apiResourceList != nil {
 			// even in case of error, some fallback might have been returned.
 			groupVersionResources[groupVersion] = apiResourceList
@@ -290,3 +300,13 @@ func (m *mapper) fetchGroupVersionResources(groupName string, versions ...string
 
 	return groupVersionResources, nil
 }
+
+// isGroupVersionCached checks if a version for a group is cached in the known groups cache.
+func (m *mapper) isGroupVersionCached(gv schema.GroupVersion) bool {
+	if cachedGroup, ok := m.knownGroups[gv.Group]; ok {
+		_, cached := cachedGroup.VersionedResources[gv.Version]
+		return cached
+	}
+
+	return false
+}

pkg/client/apiutil/restmapper_test.go

@@ -28,9 +28,11 @@ import (
 	gomegatypes "github.com/onsi/gomega/types"
 
 	apiextensionsv1 "k8s.io/apiextensions-apiserver/pkg/apis/apiextensions/v1"
+	apierrors "k8s.io/apimachinery/pkg/api/errors"
 	"k8s.io/apimachinery/pkg/api/meta"
 	"k8s.io/apimachinery/pkg/runtime/schema"
 	"k8s.io/apimachinery/pkg/types"
+	"k8s.io/client-go/discovery"
 	"k8s.io/client-go/kubernetes/scheme"
 	"k8s.io/client-go/rest"
 
@@ -529,23 +531,7 @@ func TestLazyRestMapperProvider(t *testing.T) {
 		g.Expect(err).NotTo(gmg.HaveOccurred())
 
 		// Register another CRD in runtime - "riders.crew.example.com".
-
-		crd := &apiextensionsv1.CustomResourceDefinition{}
-		err = c.Get(context.TODO(), types.NamespacedName{Name: "drivers.crew.example.com"}, crd)
-		g.Expect(err).NotTo(gmg.HaveOccurred())
-		g.Expect(crd.Spec.Names.Kind).To(gmg.Equal("Driver"))
-
-		newCRD := &apiextensionsv1.CustomResourceDefinition{}
-		crd.DeepCopyInto(newCRD)
-		newCRD.Name = "riders.crew.example.com"
-		newCRD.Spec.Names = apiextensionsv1.CustomResourceDefinitionNames{
-			Kind:   "Rider",
-			Plural: "riders",
-		}
-		newCRD.ResourceVersion = ""
-
-		// Create the new CRD.
-		g.Expect(c.Create(context.TODO(), newCRD)).To(gmg.Succeed())
+		createNewCRD(context.TODO(), g, c, "crew.example.com", "Rider", "riders")
 
 		// Wait a bit until the CRD is registered.
 		g.Eventually(func() error {
@@ -564,6 +550,131 @@ func TestLazyRestMapperProvider(t *testing.T) {
 		g.Expect(err).NotTo(gmg.HaveOccurred())
 		g.Expect(mapping.GroupVersionKind.Kind).To(gmg.Equal("rider"))
 	})
+
+	t.Run("LazyRESTMapper should invalidate the group cache if a version is not found", func(t *testing.T) {
+		g := gmg.NewWithT(t)
+		ctx := context.Background()
+
+		httpClient, err := rest.HTTPClientFor(restCfg)
+		g.Expect(err).NotTo(gmg.HaveOccurred())
+
+		crt := newCountingRoundTripper(httpClient.Transport)
+		httpClient.Transport = crt
+
+		lazyRestMapper, err := apiutil.NewDynamicRESTMapper(restCfg, httpClient)
+		g.Expect(err).NotTo(gmg.HaveOccurred())
+
+		s := scheme.Scheme
+		err = apiextensionsv1.AddToScheme(s)
+		g.Expect(err).NotTo(gmg.HaveOccurred())
+
+		c, err := client.New(restCfg, client.Options{Scheme: s})
+		g.Expect(err).NotTo(gmg.HaveOccurred())
+
+		// Register a new CRD ina  new group to avoid collisions when deleting versions - "taxi.inventory.example.com".
+		group := "inventory.example.com"
+		kind := "Taxi"
+		plural := "taxis"
+		crdName := plural + "." + group
+		crd := createNewCRD(ctx, g, c, group, kind, plural)
+		t.Cleanup(func() {
+			g.Expect(c.Delete(ctx, crd)).To(gmg.Succeed())
+		})
+
+		// Wait until the CRD is registered.
+		discHTTP, err := rest.HTTPClientFor(restCfg)
+		g.Expect(err).NotTo(gmg.HaveOccurred())
+		discClient, err := discovery.NewDiscoveryClientForConfigAndClient(restCfg, discHTTP)
+		g.Expect(err).NotTo(gmg.HaveOccurred())
+		g.Eventually(func(g gmg.Gomega) {
+			_, err = discClient.ServerResourcesForGroupVersion(group + "/v1")
+			g.Expect(err).NotTo(gmg.HaveOccurred())
+		}).Should(gmg.Succeed(), "v1 should be available")
+
+		// There are no requests before any call
+		g.Expect(crt.GetRequestCount()).To(gmg.Equal(0))
+
+		// Since we don't specify what version we expect, restmapper will fetch them all and search there.
+		// To fetch a list of available versions
+		//  #1: GET https://host/api
+		//  #2: GET https://host/apis
+		// Then, for all available versions:
+		// 	#3: GET https://host/apis/inventory.example.com/v1
+		//	#4: GET https://host/apis/inventory.example.com/v2
+		// This should fill the cache for apiGroups and versions.
+		mapping, err := lazyRestMapper.RESTMapping(schema.GroupKind{Group: group, Kind: kind})
+		g.Expect(err).NotTo(gmg.HaveOccurred())
+		g.Expect(mapping.GroupVersionKind.Kind).To(gmg.Equal(kind))
+		g.Expect(crt.GetRequestCount()).To(gmg.Equal(4))
+		crt.Reset() // We reset the counter to check how many additional requests are made later.
+
+		// At this point v2 should be cached
+		_, err = lazyRestMapper.RESTMapping(schema.GroupKind{Group: group, Kind: kind}, "v2")
+		g.Expect(err).NotTo(gmg.HaveOccurred())
+		g.Expect(crt.GetRequestCount()).To(gmg.Equal(0))
+
+		// We update the CRD to only have v1 version.
+		g.Expect(c.Get(ctx, types.NamespacedName{Name: crdName}, crd)).To(gmg.Succeed())
+		var v1 apiextensionsv1.CustomResourceDefinitionVersion
+		for i, version := range crd.Spec.Versions {
+			if version.Name == "v1" {
+				crd.Spec.Versions[i].Storage = true
+				v1 = version
+				v1.Storage = true
+			}
+		}
+		crd.Spec.Versions = []apiextensionsv1.CustomResourceDefinitionVersion{v1}
+		g.Expect(c.Update(ctx, crd)).To(gmg.Succeed())
+
+		// We wait until v2 is not available anymore.
+		g.Eventually(func(g gmg.Gomega) {
+			_, err = discClient.ServerResourcesForGroupVersion(group + "/v2")
+			g.Expect(apierrors.IsNotFound(err)).To(gmg.BeTrue(), "v2 should not be available anymore")
+		}).Should(gmg.Succeed())
+
+		// Although v2 is not available anymore, the cache is not invalidated yet so it should return a mapping.
+		_, err = lazyRestMapper.RESTMapping(schema.GroupKind{Group: group, Kind: kind}, "v2")
+		g.Expect(err).NotTo(gmg.HaveOccurred())
+		g.Expect(crt.GetRequestCount()).To(gmg.Equal(0))
+
+		// We request Limo, which is not in the mapper because it doesn't exist.
+		// This will trigger a reload of the lazy mapper cache.
+		// Reloading the cache will read v2 again and since it's not available anymore, it should invalidate the cache.
+		// 	#1: GET https://host/apis/inventory.example.com/v1
+		// 	#2: GET https://host/apis/inventory.example.com/v2
+		_, err = lazyRestMapper.RESTMapping(schema.GroupKind{Group: group, Kind: "Limo"})
+		g.Expect(err).To(beNoMatchError())
+		g.Expect(crt.GetRequestCount()).To(gmg.Equal(2))
+		crt.Reset()
+
+		// Now we request v2 again and it should return an error since the cache was invalidated.
+		// 	#1: GET https://host/apis/inventory.example.com/v2
+		_, err = lazyRestMapper.RESTMapping(schema.GroupKind{Group: group, Kind: kind}, "v2")
+		g.Expect(err).To(beNoMatchError())
+		g.Expect(crt.GetRequestCount()).To(gmg.Equal(1))
+	})
+}
+
+func createNewCRD(ctx context.Context, g gmg.Gomega, c client.Client, group, kind, plural string) *apiextensionsv1.CustomResourceDefinition {
+	crd := &apiextensionsv1.CustomResourceDefinition{}
+	err := c.Get(ctx, types.NamespacedName{Name: "drivers.crew.example.com"}, crd)
+	g.Expect(err).NotTo(gmg.HaveOccurred())
+	g.Expect(crd.Spec.Names.Kind).To(gmg.Equal("Driver"))
+
+	newCRD := &apiextensionsv1.CustomResourceDefinition{}
+	crd.DeepCopyInto(newCRD)
+	newCRD.Spec.Group = group
+	newCRD.Name = plural + "." + group
+	newCRD.Spec.Names = apiextensionsv1.CustomResourceDefinitionNames{
+		Kind:   kind,
+		Plural: plural,
+	}
+	newCRD.ResourceVersion = ""
+
+	// Create the new CRD.
+	g.Expect(c.Create(ctx, newCRD)).To(gmg.Succeed())
+
+	return newCRD
 }
 
 func beNoMatchError() gomegatypes.GomegaMatcher {
@@ -594,6 +705,7 @@ func (e *errorMatcher) Match(actual interface{}) (success bool, err error) {
 func (e *errorMatcher) FailureMessage(actual interface{}) (message string) {
 	return format.Message(actual, fmt.Sprintf("to be %s error", e.message))
 }
+
 func (e *errorMatcher) NegatedFailureMessage(actual interface{}) (message string) {
 	return format.Message(actual, fmt.Sprintf("not to be %s error", e.message))
 }