296 lines
9.6 KiB
Go
296 lines
9.6 KiB
Go
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/*
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Copyright 2016 The Kubernetes Authors.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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package discovery
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import (
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"errors"
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"io/ioutil"
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"net/http"
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"os"
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"path/filepath"
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"sync"
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"time"
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"github.com/googleapis/gnostic/OpenAPIv2"
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"k8s.io/klog"
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metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
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"k8s.io/apimachinery/pkg/runtime"
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"k8s.io/apimachinery/pkg/version"
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"k8s.io/client-go/kubernetes/scheme"
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restclient "k8s.io/client-go/rest"
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)
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// CachedDiscoveryClient implements the functions that discovery server-supported API groups,
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// versions and resources.
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type CachedDiscoveryClient struct {
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delegate DiscoveryInterface
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// cacheDirectory is the directory where discovery docs are held. It must be unique per host:port combination to work well.
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cacheDirectory string
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// ttl is how long the cache should be considered valid
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ttl time.Duration
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// mutex protects the variables below
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mutex sync.Mutex
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// ourFiles are all filenames of cache files created by this process
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ourFiles map[string]struct{}
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// invalidated is true if all cache files should be ignored that are not ours (e.g. after Invalidate() was called)
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invalidated bool
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// fresh is true if all used cache files were ours
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fresh bool
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}
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var _ CachedDiscoveryInterface = &CachedDiscoveryClient{}
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// ServerResourcesForGroupVersion returns the supported resources for a group and version.
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func (d *CachedDiscoveryClient) ServerResourcesForGroupVersion(groupVersion string) (*metav1.APIResourceList, error) {
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filename := filepath.Join(d.cacheDirectory, groupVersion, "serverresources.json")
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cachedBytes, err := d.getCachedFile(filename)
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// 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.
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if err == nil {
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cachedResources := &metav1.APIResourceList{}
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if err := runtime.DecodeInto(scheme.Codecs.UniversalDecoder(), cachedBytes, cachedResources); err == nil {
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klog.V(10).Infof("returning cached discovery info from %v", filename)
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return cachedResources, nil
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}
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}
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liveResources, err := d.delegate.ServerResourcesForGroupVersion(groupVersion)
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if err != nil {
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klog.V(3).Infof("skipped caching discovery info due to %v", err)
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return liveResources, err
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}
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if liveResources == nil || len(liveResources.APIResources) == 0 {
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klog.V(3).Infof("skipped caching discovery info, no resources found")
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return liveResources, err
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}
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if err := d.writeCachedFile(filename, liveResources); err != nil {
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klog.V(1).Infof("failed to write cache to %v due to %v", filename, err)
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}
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return liveResources, nil
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}
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// ServerResources returns the supported resources for all groups and versions.
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func (d *CachedDiscoveryClient) ServerResources() ([]*metav1.APIResourceList, error) {
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return ServerResources(d)
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}
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// ServerGroups returns the supported groups, with information like supported versions and the
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// preferred version.
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func (d *CachedDiscoveryClient) ServerGroups() (*metav1.APIGroupList, error) {
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filename := filepath.Join(d.cacheDirectory, "servergroups.json")
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cachedBytes, err := d.getCachedFile(filename)
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// 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.
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if err == nil {
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cachedGroups := &metav1.APIGroupList{}
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if err := runtime.DecodeInto(scheme.Codecs.UniversalDecoder(), cachedBytes, cachedGroups); err == nil {
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klog.V(10).Infof("returning cached discovery info from %v", filename)
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return cachedGroups, nil
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}
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}
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liveGroups, err := d.delegate.ServerGroups()
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if err != nil {
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klog.V(3).Infof("skipped caching discovery info due to %v", err)
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return liveGroups, err
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}
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if liveGroups == nil || len(liveGroups.Groups) == 0 {
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klog.V(3).Infof("skipped caching discovery info, no groups found")
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return liveGroups, err
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}
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if err := d.writeCachedFile(filename, liveGroups); err != nil {
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klog.V(1).Infof("failed to write cache to %v due to %v", filename, err)
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}
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return liveGroups, nil
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}
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func (d *CachedDiscoveryClient) getCachedFile(filename string) ([]byte, error) {
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// after invalidation ignore cache files not created by this process
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d.mutex.Lock()
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_, ourFile := d.ourFiles[filename]
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if d.invalidated && !ourFile {
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d.mutex.Unlock()
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return nil, errors.New("cache invalidated")
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}
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d.mutex.Unlock()
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file, err := os.Open(filename)
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if err != nil {
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return nil, err
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}
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defer file.Close()
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fileInfo, err := file.Stat()
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if err != nil {
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return nil, err
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}
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if time.Now().After(fileInfo.ModTime().Add(d.ttl)) {
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return nil, errors.New("cache expired")
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}
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// the cache is present and its valid. Try to read and use it.
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cachedBytes, err := ioutil.ReadAll(file)
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if err != nil {
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return nil, err
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}
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d.mutex.Lock()
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defer d.mutex.Unlock()
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d.fresh = d.fresh && ourFile
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return cachedBytes, nil
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}
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func (d *CachedDiscoveryClient) writeCachedFile(filename string, obj runtime.Object) error {
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if err := os.MkdirAll(filepath.Dir(filename), 0755); err != nil {
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return err
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}
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bytes, err := runtime.Encode(scheme.Codecs.LegacyCodec(), obj)
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if err != nil {
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return err
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}
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f, err := ioutil.TempFile(filepath.Dir(filename), filepath.Base(filename)+".")
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if err != nil {
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return err
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}
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defer os.Remove(f.Name())
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_, err = f.Write(bytes)
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if err != nil {
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return err
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}
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err = os.Chmod(f.Name(), 0755)
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if err != nil {
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return err
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}
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name := f.Name()
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err = f.Close()
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if err != nil {
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return err
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}
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// atomic rename
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d.mutex.Lock()
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defer d.mutex.Unlock()
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err = os.Rename(name, filename)
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if err == nil {
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d.ourFiles[filename] = struct{}{}
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}
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return err
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}
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// RESTClient returns a RESTClient that is used to communicate with API server
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// by this client implementation.
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func (d *CachedDiscoveryClient) RESTClient() restclient.Interface {
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return d.delegate.RESTClient()
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}
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// ServerPreferredResources returns the supported resources with the version preferred by the
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// server.
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func (d *CachedDiscoveryClient) ServerPreferredResources() ([]*metav1.APIResourceList, error) {
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return ServerPreferredResources(d)
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}
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// ServerPreferredNamespacedResources returns the supported namespaced resources with the
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// version preferred by the server.
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func (d *CachedDiscoveryClient) ServerPreferredNamespacedResources() ([]*metav1.APIResourceList, error) {
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return ServerPreferredNamespacedResources(d)
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}
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// ServerVersion retrieves and parses the server's version (git version).
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func (d *CachedDiscoveryClient) ServerVersion() (*version.Info, error) {
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return d.delegate.ServerVersion()
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}
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// OpenAPISchema retrieves and parses the swagger API schema the server supports.
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func (d *CachedDiscoveryClient) OpenAPISchema() (*openapi_v2.Document, error) {
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return d.delegate.OpenAPISchema()
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}
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// Fresh is supposed to tell the caller whether or not to retry if the cache
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// fails to find something (false = retry, true = no need to retry).
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func (d *CachedDiscoveryClient) Fresh() bool {
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d.mutex.Lock()
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defer d.mutex.Unlock()
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return d.fresh
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}
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// Invalidate enforces that no cached data is used in the future that is older than the current time.
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func (d *CachedDiscoveryClient) Invalidate() {
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d.mutex.Lock()
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defer d.mutex.Unlock()
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d.ourFiles = map[string]struct{}{}
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d.fresh = true
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d.invalidated = true
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}
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// NewCachedDiscoveryClientForConfig creates a new DiscoveryClient for the given config, and wraps
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// the created client in a CachedDiscoveryClient. The provided configuration is updated with a
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// custom transport that understands cache responses.
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// We receive two distinct cache directories for now, in order to preserve old behavior
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// which makes use of the --cache-dir flag value for storing cache data from the CacheRoundTripper,
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// and makes use of the hardcoded destination (~/.kube/cache/discovery/...) for storing
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// CachedDiscoveryClient cache data. If httpCacheDir is empty, the restconfig's transport will not
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// be updated with a roundtripper that understands cache responses.
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// If discoveryCacheDir is empty, cached server resource data will be looked up in the current directory.
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// TODO(juanvallejo): the value of "--cache-dir" should be honored. Consolidate discoveryCacheDir with httpCacheDir
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// so that server resources and http-cache data are stored in the same location, provided via config flags.
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func NewCachedDiscoveryClientForConfig(config *restclient.Config, discoveryCacheDir, httpCacheDir string, ttl time.Duration) (*CachedDiscoveryClient, error) {
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if len(httpCacheDir) > 0 {
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// update the given restconfig with a custom roundtripper that
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// understands how to handle cache responses.
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wt := config.WrapTransport
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config.WrapTransport = func(rt http.RoundTripper) http.RoundTripper {
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if wt != nil {
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rt = wt(rt)
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}
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return newCacheRoundTripper(httpCacheDir, rt)
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}
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}
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discoveryClient, err := NewDiscoveryClientForConfig(config)
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if err != nil {
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return nil, err
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}
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return newCachedDiscoveryClient(discoveryClient, discoveryCacheDir, ttl), nil
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}
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// 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.
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func newCachedDiscoveryClient(delegate DiscoveryInterface, cacheDirectory string, ttl time.Duration) *CachedDiscoveryClient {
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return &CachedDiscoveryClient{
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delegate: delegate,
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cacheDirectory: cacheDirectory,
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ttl: ttl,
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ourFiles: map[string]struct{}{},
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fresh: true,
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}
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}
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