begin building a config flags struct

pkg/kubectl/cmd/util/config_flags.go

@@ -0,0 +1,121 @@
+/*
+Copyright 2018 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 (
+	"net/http"
+	"os"
+	"path/filepath"
+	"time"
+
+	"github.com/spf13/cobra"
+
+	"k8s.io/client-go/discovery"
+	"k8s.io/client-go/rest"
+	"k8s.io/client-go/tools/clientcmd"
+	"k8s.io/client-go/util/homedir"
+
+	"k8s.io/kubernetes/pkg/kubectl/util/transport"
+)
+
+// ConfigFlags composes the set of values necessary
+// for obtaining a REST client config
+type ConfigFlags struct {
+	CacheDir   *string
+	KubeConfig *string
+}
+
+// ToRESTConfig returns a REST client configuration based on a provided
+// path to a .kubeconfig file, loading rules, and config flag overrides.
+// Expects the AddFlags method to have been called.
+func (f *ConfigFlags) ToRESTConfig() (*rest.Config, error) {
+	loadingRules := clientcmd.NewDefaultClientConfigLoadingRules()
+	// use the standard defaults for this client command
+	// DEPRECATED: remove and replace with something more accurate
+	loadingRules.DefaultClientConfig = &clientcmd.DefaultClientConfig
+
+	if f.KubeConfig != nil {
+		loadingRules.ExplicitPath = *f.KubeConfig
+	}
+
+	overrides := &clientcmd.ConfigOverrides{ClusterDefaults: clientcmd.ClusterDefaults}
+	clientConfig := clientcmd.NewInteractiveDeferredLoadingClientConfig(loadingRules, overrides, os.Stdin)
+
+	return clientConfig.ClientConfig()
+}
+
+// ToDiscoveryClient returns a CachedDiscoveryInterface using a computed RESTConfig.
+// Expects the AddFlags method to have been called.
+func (f *ConfigFlags) ToDiscoveryClient() (discovery.CachedDiscoveryInterface, error) {
+	config, err := f.ToRESTConfig()
+	if err != nil {
+		return nil, err
+	}
+
+	// The more groups you have, the more discovery requests you need to make.
+	// given 25 groups (our groups + a few custom resources) with one-ish version each, discovery needs to make 50 requests
+	// double it just so we don't end up here again for a while.  This config is only used for discovery.
+	config.Burst = 100
+
+	cacheDir := ""
+	if f.CacheDir != nil {
+		cacheDir = *f.CacheDir
+	}
+
+	if len(cacheDir) > 0 {
+		wt := config.WrapTransport
+		config.WrapTransport = func(rt http.RoundTripper) http.RoundTripper {
+			if wt != nil {
+				rt = wt(rt)
+			}
+			return transport.NewCacheRoundTripper(cacheDir, rt)
+		}
+	}
+
+	discoveryClient, err := discovery.NewDiscoveryClientForConfig(config)
+	if err != nil {
+		return nil, err
+	}
+	cacheDir = computeDiscoverCacheDir(filepath.Join(homedir.HomeDir(), ".kube", "cache", "discovery"), config.Host)
+	return NewCachedDiscoveryClient(discoveryClient, cacheDir, time.Duration(10*time.Minute)), nil
+}
+
+func (f *ConfigFlags) AddFlags(cmd *cobra.Command) {
+	flagNames := clientcmd.RecommendedConfigOverrideFlags("")
+	// short flagnames are disabled by default.  These are here for compatibility with existing scripts
+	flagNames.ClusterOverrideFlags.APIServer.ShortName = "s"
+
+	overrides := &clientcmd.ConfigOverrides{ClusterDefaults: clientcmd.ClusterDefaults}
+	clientcmd.BindOverrideFlags(overrides, cmd.Flags(), flagNames)
+
+	if f.KubeConfig != nil {
+		cmd.Flags().StringVar(f.KubeConfig, "kubeconfig", *f.KubeConfig, "Path to the kubeconfig file to use for CLI requests.")
+	}
+	if f.CacheDir != nil {
+		cmd.Flags().StringVar(f.CacheDir, FlagHTTPCacheDir, *f.CacheDir, "Default HTTP cache directory")
+	}
+}
+
+func NewConfigFlags() *ConfigFlags {
+	defaultCacheDir := filepath.Join(homedir.HomeDir(), ".kube", "http-cache")
+	kubeConfig := ""
+
+	return &ConfigFlags{
+		CacheDir:   &defaultCacheDir,
+		KubeConfig: &kubeConfig,
+	}
+}