Merge pull request #35418 from sttts/sttts-discovery-cache

Automatic merge from submit-queue

Add caching for discovery info with invalidation on cache-miss

TODO:
- [x] write tests for `CachedDiscoveryClient`
- [x] write tests for `DeferredDiscoveryRESTMapper` on cache-miss
- [x] find better way/structure to get rid of `invalidateCh` in c06ba3175b

pkg/client/typed/discovery/BUILD

@@ -32,6 +32,7 @@ go_library(
         "//pkg/version:go_default_library",
         "//plugin/pkg/client/auth:go_default_library",
         "//vendor:github.com/emicklei/go-restful/swagger",
+        "//vendor:github.com/golang/glog",
     ],
 )
 
@@ -44,11 +45,15 @@ go_test(
     library = "go_default_library",
     tags = ["automanaged"],
     deps = [
+        "//pkg/api/errors:go_default_library",
         "//pkg/api/unversioned:go_default_library",
         "//pkg/api/v1:go_default_library",
+        "//pkg/apimachinery/registered:go_default_library",
         "//pkg/client/restclient:go_default_library",
+        "//pkg/client/restclient/fake:go_default_library",
         "//pkg/version:go_default_library",
         "//vendor:github.com/emicklei/go-restful/swagger",
+        "//vendor:github.com/stretchr/testify/assert",
     ],
 )
 

pkg/client/typed/discovery/discovery_client.go

@@ -45,6 +45,15 @@ type DiscoveryInterface interface {
 	SwaggerSchemaInterface
 }
 
+// CachedDiscoveryInterface is a DiscoveryInterface with cache invalidation and freshness.
+type CachedDiscoveryInterface interface {
+	DiscoveryInterface
+	// Fresh returns true if no cached data was used that had been retrieved before the instantiation.
+	Fresh() bool
+	// Invalidate enforces that no cached data is used in the future that is older than the current time.
+	Invalidate()
+}
+
 // ServerGroupsInterface has methods for obtaining supported groups on the API server
 type ServerGroupsInterface interface {
 	// ServerGroups returns the supported groups, with information like supported versions and the

pkg/client/typed/discovery/restmapper.go

@@ -23,6 +23,8 @@ import (
 	"k8s.io/kubernetes/pkg/api/errors"
 	"k8s.io/kubernetes/pkg/api/meta"
 	"k8s.io/kubernetes/pkg/api/unversioned"
+
+	"github.com/golang/glog"
 )
 
 // APIGroupResources is an API group with a mapping of versions to
@@ -35,7 +37,7 @@ type APIGroupResources struct {
 }
 
 // NewRESTMapper returns a PriorityRESTMapper based on the discovered
-// groups and resourced passed in.
+// groups and resources passed in.
 func NewRESTMapper(groupResources []*APIGroupResources, versionInterfaces meta.VersionInterfacesFunc) meta.RESTMapper {
 	unionMapper := meta.MultiRESTMapper{}
 
@@ -47,8 +49,8 @@ func NewRESTMapper(groupResources []*APIGroupResources, versionInterfaces meta.V
 		groupPriority = append(groupPriority, group.Group.Name)
 
 		if len(group.Group.PreferredVersion.Version) != 0 {
-			preffered := group.Group.PreferredVersion.Version
+			preferred := group.Group.PreferredVersion.Version
-			if _, ok := group.VersionedResources[preffered]; ok {
+			if _, ok := group.VersionedResources[preferred]; ok {
 				resourcePriority = append(resourcePriority, unversioned.GroupVersionResource{
 					Group:    group.Group.Name,
 					Version:  group.Group.PreferredVersion.Version,
@@ -141,14 +143,14 @@ func GetAPIGroupResources(cl DiscoveryInterface) ([]*APIGroupResources, error) {
 type DeferredDiscoveryRESTMapper struct {
 	initMu           sync.Mutex
 	delegate         meta.RESTMapper
-	cl               DiscoveryInterface
+	cl               CachedDiscoveryInterface
 	versionInterface meta.VersionInterfacesFunc
 }
 
 // NewDeferredDiscoveryRESTMapper returns a
 // DeferredDiscoveryRESTMapper that will lazily query the provided
 // client for discovery information to do REST mappings.
-func NewDeferredDiscoveryRESTMapper(cl DiscoveryInterface, versionInterface meta.VersionInterfacesFunc) *DeferredDiscoveryRESTMapper {
+func NewDeferredDiscoveryRESTMapper(cl CachedDiscoveryInterface, versionInterface meta.VersionInterfacesFunc) *DeferredDiscoveryRESTMapper {
 	return &DeferredDiscoveryRESTMapper{
 		cl:               cl,
 		versionInterface: versionInterface,
@@ -175,79 +177,118 @@ func (d *DeferredDiscoveryRESTMapper) getDelegate() (meta.RESTMapper, error) {
 // Reset resets the internally cached Discovery information and will
 // cause the next mapping request to re-discover.
 func (d *DeferredDiscoveryRESTMapper) Reset() {
+	glog.V(5).Info("Invalidating discovery information")
+
 	d.initMu.Lock()
+	defer d.initMu.Unlock()
+
+	d.cl.Invalidate()
 	d.delegate = nil
-	d.initMu.Unlock()
 }
 
 // KindFor takes a partial resource and returns back the single match.
 // It returns an error if there are multiple matches.
-func (d *DeferredDiscoveryRESTMapper) KindFor(resource unversioned.GroupVersionResource) (unversioned.GroupVersionKind, error) {
+func (d *DeferredDiscoveryRESTMapper) KindFor(resource unversioned.GroupVersionResource) (gvk unversioned.GroupVersionKind, err error) {
 	del, err := d.getDelegate()
 	if err != nil {
 		return unversioned.GroupVersionKind{}, err
 	}
-	return del.KindFor(resource)
+	gvk, err = del.KindFor(resource)
+	if err != nil && !d.cl.Fresh() {
+		d.Reset()
+		gvk, err = d.KindFor(resource)
+	}
+	return
 }
 
 // KindsFor takes a partial resource and returns back the list of
 // potential kinds in priority order.
-func (d *DeferredDiscoveryRESTMapper) KindsFor(resource unversioned.GroupVersionResource) ([]unversioned.GroupVersionKind, error) {
+func (d *DeferredDiscoveryRESTMapper) KindsFor(resource unversioned.GroupVersionResource) (gvks []unversioned.GroupVersionKind, err error) {
 	del, err := d.getDelegate()
 	if err != nil {
 		return nil, err
 	}
-	return del.KindsFor(resource)
+	gvks, err = del.KindsFor(resource)
+	if len(gvks) == 0 && !d.cl.Fresh() {
+		d.Reset()
+		gvks, err = d.KindsFor(resource)
+	}
+	return
 }
 
 // ResourceFor takes a partial resource and returns back the single
 // match. It returns an error if there are multiple matches.
-func (d *DeferredDiscoveryRESTMapper) ResourceFor(input unversioned.GroupVersionResource) (unversioned.GroupVersionResource, error) {
+func (d *DeferredDiscoveryRESTMapper) ResourceFor(input unversioned.GroupVersionResource) (gvr unversioned.GroupVersionResource, err error) {
 	del, err := d.getDelegate()
 	if err != nil {
 		return unversioned.GroupVersionResource{}, err
 	}
-	return del.ResourceFor(input)
+	gvr, err = del.ResourceFor(input)
+	if err != nil && !d.cl.Fresh() {
+		d.Reset()
+		gvr, err = d.ResourceFor(input)
+	}
+	return
 }
 
 // ResourcesFor takes a partial resource and returns back the list of
 // potential resource in priority order.
-func (d *DeferredDiscoveryRESTMapper) ResourcesFor(input unversioned.GroupVersionResource) ([]unversioned.GroupVersionResource, error) {
+func (d *DeferredDiscoveryRESTMapper) ResourcesFor(input unversioned.GroupVersionResource) (gvrs []unversioned.GroupVersionResource, err error) {
 	del, err := d.getDelegate()
 	if err != nil {
 		return nil, err
 	}
-	return del.ResourcesFor(input)
+	gvrs, err = del.ResourcesFor(input)
+	if len(gvrs) == 0 && !d.cl.Fresh() {
+		d.Reset()
+		gvrs, err = d.ResourcesFor(input)
+	}
+	return
 }
 
 // RESTMapping identifies a preferred resource mapping for the
 // provided group kind.
-func (d *DeferredDiscoveryRESTMapper) RESTMapping(gk unversioned.GroupKind, versions ...string) (*meta.RESTMapping, error) {
+func (d *DeferredDiscoveryRESTMapper) RESTMapping(gk unversioned.GroupKind, versions ...string) (m *meta.RESTMapping, err error) {
 	del, err := d.getDelegate()
 	if err != nil {
 		return nil, err
 	}
-	return del.RESTMapping(gk, versions...)
+	m, err = del.RESTMapping(gk, versions...)
+	if err != nil && !d.cl.Fresh() {
+		d.Reset()
+		m, err = d.RESTMapping(gk, versions...)
+	}
+	return
 }
 
 // RESTMappings returns the RESTMappings for the provided group kind
 // in a rough internal preferred order. If no kind is found, it will
 // return a NoResourceMatchError.
-func (d *DeferredDiscoveryRESTMapper) RESTMappings(gk unversioned.GroupKind) ([]*meta.RESTMapping, error) {
+func (d *DeferredDiscoveryRESTMapper) RESTMappings(gk unversioned.GroupKind) (ms []*meta.RESTMapping, err error) {
 	del, err := d.getDelegate()
 	if err != nil {
 		return nil, err
 	}
-	return del.RESTMappings(gk)
+	ms, err = del.RESTMappings(gk)
+	if len(ms) == 0 && !d.cl.Fresh() {
+		d.Reset()
+		ms, err = d.RESTMappings(gk)
+	}
+	return
 }
 
 // AliasesForResource returns whether a resource has an alias or not.
-func (d *DeferredDiscoveryRESTMapper) AliasesForResource(resource string) ([]string, bool) {
+func (d *DeferredDiscoveryRESTMapper) AliasesForResource(resource string) (as []string, ok bool) {
 	del, err := d.getDelegate()
 	if err != nil {
 		return nil, false
 	}
-	return del.AliasesForResource(resource)
+	as, ok = del.AliasesForResource(resource)
+	if len(as) == 0 && !d.cl.Fresh() {
+		d.Reset()
+		as, ok = d.AliasesForResource(resource)
+	}
+	return
 }
 
 // ResourceSingularizer converts a resource name from plural to
@@ -257,7 +298,12 @@ func (d *DeferredDiscoveryRESTMapper) ResourceSingularizer(resource string) (sin
 	if err != nil {
 		return resource, err
 	}
-	return del.ResourceSingularizer(resource)
+	singular, err = del.ResourceSingularizer(resource)
+	if err != nil && !d.cl.Fresh() {
+		d.Reset()
+		singular, err = d.ResourceSingularizer(resource)
+	}
+	return
 }
 
 func (d *DeferredDiscoveryRESTMapper) String() string {

pkg/client/typed/discovery/restmapper_test.go

@@ -20,7 +20,15 @@ import (
 	"reflect"
 	"testing"
 
+	"k8s.io/kubernetes/pkg/api/errors"
 	"k8s.io/kubernetes/pkg/api/unversioned"
+	"k8s.io/kubernetes/pkg/apimachinery/registered"
+	"k8s.io/kubernetes/pkg/client/restclient"
+	"k8s.io/kubernetes/pkg/client/restclient/fake"
+	"k8s.io/kubernetes/pkg/version"
+
+	"github.com/emicklei/go-restful/swagger"
+	"github.com/stretchr/testify/assert"
 )
 
 func TestRESTMapper(t *testing.T) {
@@ -174,3 +182,144 @@ func TestRESTMapper(t *testing.T) {
 		}
 	}
 }
+
+func TestDeferredDiscoveryRESTMapper_CacheMiss(t *testing.T) {
+	assert := assert.New(t)
+
+	cdc := fakeCachedDiscoveryInterface{fresh: false}
+	m := NewDeferredDiscoveryRESTMapper(&cdc, registered.InterfacesFor)
+	assert.False(cdc.fresh, "should NOT be fresh after instantiation")
+	assert.Zero(cdc.invalidateCalls, "should not have called Invalidate()")
+
+	gvk, err := m.KindFor(unversioned.GroupVersionResource{
+		Group:    "a",
+		Version:  "v1",
+		Resource: "foo",
+	})
+	assert.NoError(err)
+	assert.True(cdc.fresh, "should be fresh after a cache-miss")
+	assert.Equal(cdc.invalidateCalls, 1, "should have called Invalidate() once")
+	assert.Equal(gvk.Kind, "Foo")
+
+	gvk, err = m.KindFor(unversioned.GroupVersionResource{
+		Group:    "a",
+		Version:  "v1",
+		Resource: "foo",
+	})
+	assert.NoError(err)
+	assert.Equal(cdc.invalidateCalls, 1, "should NOT have called Invalidate() again")
+
+	gvk, err = m.KindFor(unversioned.GroupVersionResource{
+		Group:    "a",
+		Version:  "v1",
+		Resource: "bar",
+	})
+	assert.Error(err)
+	assert.Equal(cdc.invalidateCalls, 1, "should NOT have called Invalidate() again after another cache-miss, but with fresh==true")
+
+	cdc.fresh = false
+	gvk, err = m.KindFor(unversioned.GroupVersionResource{
+		Group:    "a",
+		Version:  "v1",
+		Resource: "bar",
+	})
+	assert.Error(err)
+	assert.Equal(cdc.invalidateCalls, 2, "should HAVE called Invalidate() again after another cache-miss, but with fresh==false")
+}
+
+type fakeCachedDiscoveryInterface struct {
+	invalidateCalls int
+	fresh           bool
+	enabledA        bool
+}
+
+var _ CachedDiscoveryInterface = &fakeCachedDiscoveryInterface{}
+
+func (c *fakeCachedDiscoveryInterface) Fresh() bool {
+	return c.fresh
+}
+
+func (c *fakeCachedDiscoveryInterface) Invalidate() {
+	c.invalidateCalls = c.invalidateCalls + 1
+	c.fresh = true
+	c.enabledA = true
+}
+
+func (c *fakeCachedDiscoveryInterface) RESTClient() restclient.Interface {
+	return &fake.RESTClient{}
+}
+
+func (c *fakeCachedDiscoveryInterface) ServerGroups() (*unversioned.APIGroupList, error) {
+	if c.enabledA {
+		return &unversioned.APIGroupList{
+			Groups: []unversioned.APIGroup{
+				{
+					Name: "a",
+					Versions: []unversioned.GroupVersionForDiscovery{
+						{
+							GroupVersion: "a/v1",
+							Version:      "v1",
+						},
+					},
+					PreferredVersion: unversioned.GroupVersionForDiscovery{
+						GroupVersion: "a/v1",
+						Version:      "v1",
+					},
+				},
+			},
+		}, nil
+	}
+	return &unversioned.APIGroupList{}, nil
+}
+
+func (c *fakeCachedDiscoveryInterface) ServerResourcesForGroupVersion(groupVersion string) (*unversioned.APIResourceList, error) {
+	if c.enabledA && groupVersion == "a/v1" {
+		return &unversioned.APIResourceList{
+			GroupVersion: "a/v1",
+			APIResources: []unversioned.APIResource{
+				{
+					Name:       "foo",
+					Kind:       "Foo",
+					Namespaced: false,
+				},
+			},
+		}, nil
+	}
+
+	return nil, errors.NewNotFound(unversioned.GroupResource{}, "")
+}
+
+func (c *fakeCachedDiscoveryInterface) ServerResources() (map[string]*unversioned.APIResourceList, error) {
+	if c.enabledA {
+		av1, _ := c.ServerResourcesForGroupVersion("a/v1")
+		return map[string]*unversioned.APIResourceList{
+			"a/v1": av1,
+		}, nil
+	}
+	return map[string]*unversioned.APIResourceList{}, nil
+}
+
+func (c *fakeCachedDiscoveryInterface) ServerPreferredResources() ([]unversioned.GroupVersionResource, error) {
+	if c.enabledA {
+		return []unversioned.GroupVersionResource{
+			{
+				Group:    "a",
+				Version:  "v1",
+				Resource: "foo",
+			},
+		}, nil
+	}
+	return []unversioned.GroupVersionResource{}, nil
+}
+
+func (c *fakeCachedDiscoveryInterface) ServerPreferredNamespacedResources() ([]unversioned.GroupVersionResource, error) {
+	return []unversioned.GroupVersionResource{}, nil
+}
+
+func (c *fakeCachedDiscoveryInterface) ServerVersion() (*version.Info, error) {
+	return &version.Info{}, nil
+}
+
+func (c *fakeCachedDiscoveryInterface) SwaggerSchema(version unversioned.GroupVersion) (*swagger.ApiDeclaration, error) {
+	return &swagger.ApiDeclaration{}, nil
+}

pkg/kubectl/cmd/testing/fake.go

@@ -133,6 +133,17 @@ func newExternalScheme() (*runtime.Scheme, meta.RESTMapper, runtime.Codec) {
 	return scheme, mapper, codec
 }
 
+type fakeCachedDiscoveryClient struct {
+	discovery.DiscoveryInterface
+}
+
+func (d *fakeCachedDiscoveryClient) Fresh() bool {
+	return true
+}
+
+func (d *fakeCachedDiscoveryClient) Invalidate() {
+}
+
 type TestFactory struct {
 	Mapper       meta.RESTMapper
 	Typer        runtime.ObjectTyper
@@ -164,6 +175,14 @@ func NewTestFactory() (cmdutil.Factory, *TestFactory, runtime.Codec, runtime.Neg
 	}, t, codec, negotiatedSerializer
 }
 
+func (f *FakeFactory) DiscoveryClient() (discovery.CachedDiscoveryInterface, error) {
+	discoveryClient, err := discovery.NewDiscoveryClientForConfig(f.tf.ClientConfig)
+	if err != nil {
+		return nil, err
+	}
+	return &fakeCachedDiscoveryClient{DiscoveryInterface: discoveryClient}, nil
+}
+
 func (f *FakeFactory) FlagSet() *pflag.FlagSet {
 	return nil
 }

pkg/kubectl/cmd/util/BUILD

@@ -13,6 +13,7 @@ load(
 go_library(
     name = "go_default_library",
     srcs = [
+        "cached_discovery.go",
         "clientcache.go",
         "factory.go",
         "helpers.go",
@@ -50,8 +51,10 @@ go_library(
         "//pkg/util/errors:go_default_library",
         "//pkg/util/exec:go_default_library",
         "//pkg/util/flag:go_default_library",
+        "//pkg/util/homedir:go_default_library",
         "//pkg/util/sets:go_default_library",
         "//pkg/util/strategicpatch:go_default_library",
+        "//pkg/version:go_default_library",
         "//pkg/watch:go_default_library",
         "//vendor:github.com/emicklei/go-restful/swagger",
         "//vendor:github.com/evanphx/json-patch",
@@ -64,6 +67,7 @@ go_library(
 go_test(
     name = "go_default_test",
     srcs = [
+        "cached_discovery_test.go",
         "factory_test.go",
         "helpers_test.go",
         "shortcut_restmapper_test.go",
@@ -85,8 +89,10 @@ go_test(
         "//pkg/apimachinery/registered:go_default_library",
         "//pkg/apis/extensions:go_default_library",
         "//pkg/client/clientset_generated/internalclientset/fake:go_default_library",
+        "//pkg/client/restclient:go_default_library",
         "//pkg/client/restclient/fake:go_default_library",
         "//pkg/client/testing/core:go_default_library",
+        "//pkg/client/typed/discovery:go_default_library",
         "//pkg/client/unversioned/clientcmd:go_default_library",
         "//pkg/client/unversioned/clientcmd/api:go_default_library",
         "//pkg/controller:go_default_library",
@@ -97,6 +103,9 @@ go_test(
         "//pkg/util/exec:go_default_library",
         "//pkg/util/flag:go_default_library",
         "//pkg/util/validation/field:go_default_library",
+        "//pkg/version:go_default_library",
         "//pkg/watch:go_default_library",
+        "//vendor:github.com/emicklei/go-restful/swagger",
+        "//vendor:github.com/stretchr/testify/assert",
     ],
 )

pkg/kubectl/cmd/util/cached_discovery.go

@@ -0,0 +1,252 @@
+/*
+Copyright 2016 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package util
+
+import (
+	"errors"
+	"io/ioutil"
+	"os"
+	"path/filepath"
+	"sync"
+	"time"
+
+	"github.com/emicklei/go-restful/swagger"
+	"github.com/golang/glog"
+
+	"k8s.io/kubernetes/pkg/api"
+	"k8s.io/kubernetes/pkg/api/unversioned"
+	"k8s.io/kubernetes/pkg/client/restclient"
+	"k8s.io/kubernetes/pkg/client/typed/discovery"
+	"k8s.io/kubernetes/pkg/runtime"
+	"k8s.io/kubernetes/pkg/version"
+)
+
+// CachedDiscoveryClient implements the functions that discovery server-supported API groups,
+// versions and resources.
+type CachedDiscoveryClient struct {
+	delegate discovery.DiscoveryInterface
+
+	// cacheDirectory is the directory where discovery docs are held.  It must be unique per host:port combination to work well.
+	cacheDirectory string
+
+	// ttl is how long the cache should be considered valid
+	ttl time.Duration
+
+	// mutex protects the variables below
+	mutex sync.Mutex
+
+	// ourFiles are all filenames of cache files created by this process
+	ourFiles map[string]struct{}
+	// invalidated is true if all cache files should be ignored that are not ours (e.g. after Invalidate() was called)
+	invalidated bool
+	// fresh is true if all used cache files were ours
+	fresh bool
+}
+
+var _ discovery.CachedDiscoveryInterface = &CachedDiscoveryClient{}
+
+// ServerResourcesForGroupVersion returns the supported resources for a group and version.
+func (d *CachedDiscoveryClient) ServerResourcesForGroupVersion(groupVersion string) (*unversioned.APIResourceList, error) {
+	filename := filepath.Join(d.cacheDirectory, groupVersion, "serverresources.json")
+	cachedBytes, err := d.getCachedFile(filename)
+	// don't fail on errors, we either don't have a file or won't be able to run the cached check. Either way we can fallback.
+	if err == nil {
+		cachedResources := &unversioned.APIResourceList{}
+		if err := runtime.DecodeInto(api.Codecs.UniversalDecoder(), cachedBytes, cachedResources); err == nil {
+			glog.V(6).Infof("returning cached discovery info from %v", filename)
+			return cachedResources, nil
+		}
+	}
+
+	liveResources, err := d.delegate.ServerResourcesForGroupVersion(groupVersion)
+	if err != nil {
+		return liveResources, err
+	}
+
+	if err := d.writeCachedFile(filename, liveResources); err != nil {
+		glog.V(3).Infof("failed to write cache to %v due to %v", filename, err)
+	}
+
+	return liveResources, nil
+}
+
+// ServerResources returns the supported resources for all groups and versions.
+func (d *CachedDiscoveryClient) ServerResources() (map[string]*unversioned.APIResourceList, error) {
+	apiGroups, err := d.ServerGroups()
+	if err != nil {
+		return nil, err
+	}
+	groupVersions := unversioned.ExtractGroupVersions(apiGroups)
+	result := map[string]*unversioned.APIResourceList{}
+	for _, groupVersion := range groupVersions {
+		resources, err := d.ServerResourcesForGroupVersion(groupVersion)
+		if err != nil {
+			return nil, err
+		}
+		result[groupVersion] = resources
+	}
+	return result, nil
+}
+
+func (d *CachedDiscoveryClient) ServerGroups() (*unversioned.APIGroupList, error) {
+	filename := filepath.Join(d.cacheDirectory, "servergroups.json")
+	cachedBytes, err := d.getCachedFile(filename)
+	// don't fail on errors, we either don't have a file or won't be able to run the cached check. Either way we can fallback.
+	if err == nil {
+		cachedGroups := &unversioned.APIGroupList{}
+		if err := runtime.DecodeInto(api.Codecs.UniversalDecoder(), cachedBytes, cachedGroups); err == nil {
+			glog.V(6).Infof("returning cached discovery info from %v", filename)
+			return cachedGroups, nil
+		}
+	}
+
+	liveGroups, err := d.delegate.ServerGroups()
+	if err != nil {
+		return liveGroups, err
+	}
+
+	if err := d.writeCachedFile(filename, liveGroups); err != nil {
+		glog.V(3).Infof("failed to write cache to %v due to %v", filename, err)
+	}
+
+	return liveGroups, nil
+}
+
+func (d *CachedDiscoveryClient) getCachedFile(filename string) ([]byte, error) {
+	// after invalidation ignore cache files not created by this process
+	d.mutex.Lock()
+	_, ourFile := d.ourFiles[filename]
+	if d.invalidated && !ourFile {
+		d.mutex.Unlock()
+		return nil, errors.New("cache invalidated")
+	}
+	d.mutex.Unlock()
+
+	file, err := os.Open(filename)
+	if err != nil {
+		return nil, err
+	}
+
+	fileInfo, err := file.Stat()
+	if err != nil {
+		return nil, err
+	}
+
+	if time.Now().After(fileInfo.ModTime().Add(d.ttl)) {
+		return nil, errors.New("cache expired")
+	}
+
+	// the cache is present and its valid.  Try to read and use it.
+	cachedBytes, err := ioutil.ReadAll(file)
+	if err != nil {
+		return nil, err
+	}
+
+	d.mutex.Lock()
+	defer d.mutex.Unlock()
+	d.fresh = d.fresh && ourFile
+
+	return cachedBytes, nil
+}
+
+func (d *CachedDiscoveryClient) writeCachedFile(filename string, obj runtime.Object) error {
+	if err := os.MkdirAll(filepath.Dir(filename), 0755); err != nil {
+		return err
+	}
+
+	bytes, err := runtime.Encode(api.Codecs.LegacyCodec(), obj)
+	if err != nil {
+		return err
+	}
+
+	f, err := ioutil.TempFile(filepath.Dir(filename), filepath.Base(filename)+".")
+	if err != nil {
+		return err
+	}
+	defer os.Remove(f.Name())
+	_, err = f.Write(bytes)
+	if err != nil {
+		return err
+	}
+
+	err = f.Chmod(0755)
+	if err != nil {
+		return err
+	}
+
+	name := f.Name()
+	err = f.Close()
+	if err != nil {
+		return err
+	}
+
+	// atomic rename
+	d.mutex.Lock()
+	defer d.mutex.Unlock()
+	err = os.Rename(name, filename)
+	if err == nil {
+		d.ourFiles[filename] = struct{}{}
+	}
+	return err
+}
+
+func (d *CachedDiscoveryClient) RESTClient() restclient.Interface {
+	return d.delegate.RESTClient()
+}
+
+func (d *CachedDiscoveryClient) ServerPreferredResources() ([]unversioned.GroupVersionResource, error) {
+	return d.delegate.ServerPreferredResources()
+}
+
+func (d *CachedDiscoveryClient) ServerPreferredNamespacedResources() ([]unversioned.GroupVersionResource, error) {
+	return d.delegate.ServerPreferredNamespacedResources()
+}
+
+func (d *CachedDiscoveryClient) ServerVersion() (*version.Info, error) {
+	return d.delegate.ServerVersion()
+}
+
+func (d *CachedDiscoveryClient) SwaggerSchema(version unversioned.GroupVersion) (*swagger.ApiDeclaration, error) {
+	return d.delegate.SwaggerSchema(version)
+}
+
+func (d *CachedDiscoveryClient) Fresh() bool {
+	d.mutex.Lock()
+	defer d.mutex.Unlock()
+
+	return d.fresh
+}
+
+func (d *CachedDiscoveryClient) Invalidate() {
+	d.mutex.Lock()
+	defer d.mutex.Unlock()
+
+	d.ourFiles = map[string]struct{}{}
+	d.fresh = true
+	d.invalidated = true
+}
+
+// NewCachedDiscoveryClient creates a new DiscoveryClient.  cacheDirectory is the directory where discovery docs are held.  It must be unique per host:port combination to work well.
+func NewCachedDiscoveryClient(delegate discovery.DiscoveryInterface, cacheDirectory string, ttl time.Duration) *CachedDiscoveryClient {
+	return &CachedDiscoveryClient{
+		delegate:       delegate,
+		cacheDirectory: cacheDirectory,
+		ttl:            ttl,
+		ourFiles:       map[string]struct{}{},
+		fresh:          true,
+	}
+}

pkg/kubectl/cmd/util/cached_discovery_test.go

@@ -0,0 +1,164 @@
+/*
+Copyright 2016 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package util
+
+import (
+	"io/ioutil"
+	"os"
+	"testing"
+	"time"
+
+	"github.com/emicklei/go-restful/swagger"
+	"github.com/stretchr/testify/assert"
+
+	"k8s.io/kubernetes/pkg/api/errors"
+	"k8s.io/kubernetes/pkg/api/unversioned"
+	"k8s.io/kubernetes/pkg/client/restclient"
+	"k8s.io/kubernetes/pkg/client/restclient/fake"
+	"k8s.io/kubernetes/pkg/client/typed/discovery"
+	"k8s.io/kubernetes/pkg/version"
+)
+
+func TestCachedDiscoveryClient_Fresh(t *testing.T) {
+	assert := assert.New(t)
+
+	d, err := ioutil.TempDir("", "")
+	assert.NoError(err)
+	defer os.RemoveAll(d)
+
+	c := fakeDiscoveryClient{}
+	cdc := NewCachedDiscoveryClient(&c, d, 60*time.Second)
+	assert.True(cdc.Fresh(), "should be fresh after creation")
+
+	cdc.ServerGroups()
+	assert.True(cdc.Fresh(), "should be fresh after groups call without cache")
+	assert.Equal(c.groupCalls, 1)
+
+	cdc.ServerGroups()
+	assert.True(cdc.Fresh(), "should be fresh after another groups call")
+	assert.Equal(c.groupCalls, 1)
+
+	cdc.ServerResources()
+	assert.True(cdc.Fresh(), "should be fresh after resources call")
+	assert.Equal(c.resourceCalls, 1)
+
+	cdc.ServerResources()
+	assert.True(cdc.Fresh(), "should be fresh after another resources call")
+	assert.Equal(c.resourceCalls, 1)
+
+	cdc = NewCachedDiscoveryClient(&c, d, 60*time.Second)
+	cdc.ServerGroups()
+	assert.False(cdc.Fresh(), "should NOT be fresh after recreation with existing groups cache")
+	assert.Equal(c.groupCalls, 1)
+
+	cdc.ServerResources()
+	assert.False(cdc.Fresh(), "should NOT be fresh after recreation with existing resources cache")
+	assert.Equal(c.resourceCalls, 1)
+
+	cdc.Invalidate()
+	assert.True(cdc.Fresh(), "should be fresh after cache invalidation")
+
+	cdc.ServerResources()
+	assert.True(cdc.Fresh(), "should ignore existing resources cache after invalidation")
+	assert.Equal(c.resourceCalls, 2)
+}
+
+func TestNewCachedDiscoveryClient_TTL(t *testing.T) {
+	assert := assert.New(t)
+
+	d, err := ioutil.TempDir("", "")
+	assert.NoError(err)
+	defer os.RemoveAll(d)
+
+	c := fakeDiscoveryClient{}
+	cdc := NewCachedDiscoveryClient(&c, d, 1*time.Nanosecond)
+	cdc.ServerGroups()
+	assert.Equal(c.groupCalls, 1)
+
+	time.Sleep(1 * time.Second)
+
+	cdc.ServerGroups()
+	assert.Equal(c.groupCalls, 2)
+}
+
+type fakeDiscoveryClient struct {
+	groupCalls    int
+	resourceCalls int
+	versionCalls  int
+	swaggerCalls  int
+}
+
+var _ discovery.DiscoveryInterface = &fakeDiscoveryClient{}
+
+func (c *fakeDiscoveryClient) RESTClient() restclient.Interface {
+	return &fake.RESTClient{}
+}
+
+func (c *fakeDiscoveryClient) ServerGroups() (*unversioned.APIGroupList, error) {
+	c.groupCalls = c.groupCalls + 1
+	return &unversioned.APIGroupList{
+		Groups: []unversioned.APIGroup{
+			{
+				Name: "a",
+				Versions: []unversioned.GroupVersionForDiscovery{
+					{
+						GroupVersion: "a/v1",
+						Version:      "v1",
+					},
+				},
+				PreferredVersion: unversioned.GroupVersionForDiscovery{
+					GroupVersion: "a/v1",
+					Version:      "v1",
+				},
+			},
+		},
+	}, nil
+}
+
+func (c *fakeDiscoveryClient) ServerResourcesForGroupVersion(groupVersion string) (*unversioned.APIResourceList, error) {
+	c.resourceCalls = c.resourceCalls + 1
+	if groupVersion == "a/v1" {
+		return &unversioned.APIResourceList{}, nil
+	}
+
+	return nil, errors.NewNotFound(unversioned.GroupResource{}, "")
+}
+
+func (c *fakeDiscoveryClient) ServerResources() (map[string]*unversioned.APIResourceList, error) {
+	c.resourceCalls = c.resourceCalls + 1
+	return map[string]*unversioned.APIResourceList{}, nil
+}
+
+func (c *fakeDiscoveryClient) ServerPreferredResources() ([]unversioned.GroupVersionResource, error) {
+	c.resourceCalls = c.resourceCalls + 1
+	return []unversioned.GroupVersionResource{}, nil
+}
+
+func (c *fakeDiscoveryClient) ServerPreferredNamespacedResources() ([]unversioned.GroupVersionResource, error) {
+	c.resourceCalls = c.resourceCalls + 1
+	return []unversioned.GroupVersionResource{}, nil
+}
+
+func (c *fakeDiscoveryClient) ServerVersion() (*version.Info, error) {
+	c.versionCalls = c.versionCalls + 1
+	return &version.Info{}, nil
+}
+
+func (c *fakeDiscoveryClient) SwaggerSchema(version unversioned.GroupVersion) (*swagger.ApiDeclaration, error) {
+	c.swaggerCalls = c.swaggerCalls + 1
+	return &swagger.ApiDeclaration{}, nil
+}

pkg/kubectl/cmd/util/factory.go

@@ -27,6 +27,7 @@ import (
 	"os/user"
 	"path"
 	"path/filepath"
+	"regexp"
 	"sort"
 	"strconv"
 	"strings"
@@ -61,6 +62,7 @@ import (
 	"k8s.io/kubernetes/pkg/runtime"
 	"k8s.io/kubernetes/pkg/runtime/serializer/json"
 	utilflag "k8s.io/kubernetes/pkg/util/flag"
+	"k8s.io/kubernetes/pkg/util/homedir"
 	"k8s.io/kubernetes/pkg/watch"
 )
 
@@ -77,6 +79,8 @@ type Factory interface {
 	// Returns internal flagset
 	FlagSet() *pflag.FlagSet
 
+	// Returns a discovery client
+	DiscoveryClient() (discovery.CachedDiscoveryInterface, error)
 	// Returns interfaces for dealing with arbitrary runtime.Objects.
 	Object() (meta.RESTMapper, runtime.ObjectTyper)
 	// Returns interfaces for dealing with arbitrary
@@ -313,27 +317,36 @@ func NewFactory(optionalClientConfig clientcmd.ClientConfig) Factory {
 	}
 
 	clients := NewClientCache(clientConfig)
-	return &factory{
+
+	f := &factory{
 		flags:        flags,
 		clientConfig: clientConfig,
 		clients:      clients,
 	}
+
+	return f
 }
 
 func (f *factory) FlagSet() *pflag.FlagSet {
 	return f.flags
 }
 
-func (f *factory) Object() (meta.RESTMapper, runtime.ObjectTyper) {
+func (f *factory) DiscoveryClient() (discovery.CachedDiscoveryInterface, error) {
 	cfg, err := f.clientConfig.ClientConfig()
-	checkErrWithPrefix("failed to get client config: ", err)
+	if err != nil {
-	cmdApiVersion := unversioned.GroupVersion{}
+		return nil, err
-	if cfg.GroupVersion != nil {
-		cmdApiVersion = *cfg.GroupVersion
 	}
-
-	mapper := registered.RESTMapper()
 	discoveryClient, err := discovery.NewDiscoveryClientForConfig(cfg)
+	if err != nil {
+		return nil, err
+	}
+	cacheDir := computeDiscoverCacheDir(filepath.Join(homedir.HomeDir(), ".kube", "cache", "discovery"), cfg.Host)
+	return NewCachedDiscoveryClient(discoveryClient, cacheDir, time.Duration(10*time.Minute)), nil
+}
+
+func (f *factory) Object() (meta.RESTMapper, runtime.ObjectTyper) {
+	mapper := registered.RESTMapper()
+	discoveryClient, err := f.DiscoveryClient()
 	if err == nil {
 		mapper = meta.FirstHitRESTMapper{
 			MultiRESTMapper: meta.MultiRESTMapper{
@@ -345,23 +358,28 @@ func (f *factory) Object() (meta.RESTMapper, runtime.ObjectTyper) {
 
 	// wrap with shortcuts
 	mapper = NewShortcutExpander(mapper, discoveryClient)
+
 	// wrap with output preferences
+	cfg, err := f.clients.ClientConfigForVersion(nil)
+	checkErrWithPrefix("failed to get client config: ", err)
+	cmdApiVersion := unversioned.GroupVersion{}
+	if cfg.GroupVersion != nil {
+		cmdApiVersion = *cfg.GroupVersion
+	}
 	mapper = kubectl.OutputVersionMapper{RESTMapper: mapper, OutputVersions: []unversioned.GroupVersion{cmdApiVersion}}
 	return mapper, api.Scheme
 }
 
 func (f *factory) UnstructuredObject() (meta.RESTMapper, runtime.ObjectTyper, error) {
-	cfg, err := f.clients.ClientConfigForVersion(nil)
+	discoveryClient, err := f.DiscoveryClient()
 	if err != nil {
 		return nil, nil, err
 	}
-
+	groupResources, err := discovery.GetAPIGroupResources(discoveryClient)
-	dc, err := discovery.NewDiscoveryClientForConfig(cfg)
+	if err != nil && !discoveryClient.Fresh() {
-	if err != nil {
+		discoveryClient.Invalidate()
-		return nil, nil, err
+		groupResources, err = discovery.GetAPIGroupResources(discoveryClient)
 	}
-
-	groupResources, err := discovery.GetAPIGroupResources(dc)
 	if err != nil {
 		return nil, nil, err
 	}
@@ -378,11 +396,9 @@ func (f *factory) UnstructuredObject() (meta.RESTMapper, runtime.ObjectTyper, er
 		}
 	}
 
-	mapper := discovery.NewRESTMapper(groupResources, meta.InterfacesForUnstructured)
+	mapper := discovery.NewDeferredDiscoveryRESTMapper(discoveryClient, meta.InterfacesForUnstructured)
-
 	typer := discovery.NewUnstructuredObjectTyper(groupResources)
-
+	return NewShortcutExpander(mapper, discoveryClient), typer, nil
-	return NewShortcutExpander(mapper, dc), typer, nil
 }
 
 func (f *factory) RESTClient() (*restclient.RESTClient, error) {
@@ -1316,3 +1332,16 @@ func (f *factory) SuggestedPodTemplateResources() []unversioned.GroupResource {
 		{Resource: "replicaset"},
 	}
 }
+
+// overlyCautiousIllegalFileCharacters matches characters that *might* not be supported.  Windows is really restrictive, so this is really restrictive
+var overlyCautiousIllegalFileCharacters = regexp.MustCompile(`[^(\w/\.)]`)
+
+// computeDiscoverCacheDir takes the parentDir and the host and comes up with a "usually non-colliding" name.
+func computeDiscoverCacheDir(parentDir, host string) string {
+	// strip the optional scheme from host if its there:
+	schemelessHost := strings.Replace(strings.Replace(host, "https://", "", 1), "http://", "", 1)
+	// now do a simple collapse of non-AZ09 characters.  Collisions are possible but unlikely.  Even if we do collide the problem is short lived
+	safeHost := overlyCautiousIllegalFileCharacters.ReplaceAllString(schemelessHost, "_")
+
+	return filepath.Join(parentDir, safeHost)
+}

pkg/kubectl/cmd/util/shortcut_restmapper.go

@@ -25,18 +25,18 @@ import (
 	"k8s.io/kubernetes/pkg/kubectl"
 )
 
-// ShortcutExpander is a RESTMapper that can be used for OpenShift resources.   It expands the resource first, then invokes the wrapped
+// ShortcutExpander is a RESTMapper that can be used for Kubernetes resources.   It expands the resource first, then invokes the wrapped
 type ShortcutExpander struct {
 	RESTMapper meta.RESTMapper
 
 	All []unversioned.GroupResource
 
-	discoveryClient *discovery.DiscoveryClient
+	discoveryClient discovery.DiscoveryInterface
 }
 
 var _ meta.RESTMapper = &ShortcutExpander{}
 
-func NewShortcutExpander(delegate meta.RESTMapper, client *discovery.DiscoveryClient) ShortcutExpander {
+func NewShortcutExpander(delegate meta.RESTMapper, client discovery.DiscoveryInterface) ShortcutExpander {
 	return ShortcutExpander{All: userResources, RESTMapper: delegate, discoveryClient: client}
 }