add utility for binding flags and building api server clients

pkg/client/clientcmd/auth_loaders.go

@@ -0,0 +1,82 @@
+/*
+Copyright 2014 Google Inc. All rights reserved.
+
+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 clientcmd
+
+import (
+	"encoding/json"
+	"fmt"
+	"io"
+	"io/ioutil"
+	"os"
+
+	"github.com/GoogleCloudPlatform/kubernetes/pkg/clientauth"
+)
+
+// AuthLoaders are used to build clientauth.Info objects.
+type AuthLoader interface {
+	// LoadAuth takes a path to a config file and can then do anything it needs in order to return a valid clientauth.Info
+	LoadAuth(path string) (*clientauth.Info, error)
+}
+
+// default implementation of an AuthLoader
+type defaultAuthLoader struct{}
+
+// LoadAuth for defaultAuthLoader simply delegates to clientauth.LoadFromFile
+func (*defaultAuthLoader) LoadAuth(path string) (*clientauth.Info, error) {
+	return clientauth.LoadFromFile(path)
+}
+
+type promptingAuthLoader struct {
+	reader io.Reader
+}
+
+// LoadAuth parses an AuthInfo object from a file path. It prompts user and creates file if it doesn't exist.
+func (a *promptingAuthLoader) LoadAuth(path string) (*clientauth.Info, error) {
+	var auth clientauth.Info
+	// Prompt for user/pass and write a file if none exists.
+	if _, err := os.Stat(path); os.IsNotExist(err) {
+		auth.User = promptForString("Username", a.reader)
+		auth.Password = promptForString("Password", a.reader)
+		data, err := json.Marshal(auth)
+		if err != nil {
+			return &auth, err
+		}
+		err = ioutil.WriteFile(path, data, 0600)
+		return &auth, err
+	}
+	authPtr, err := clientauth.LoadFromFile(path)
+	if err != nil {
+		return nil, err
+	}
+	return authPtr, nil
+}
+func promptForString(field string, r io.Reader) string {
+	fmt.Printf("Please enter %s: ", field)
+	var result string
+	fmt.Fscan(r, &result)
+	return result
+}
+
+// NewDefaultAuthLoader is an AuthLoader that parses an AuthInfo object from a file path. It prompts user and creates file if it doesn't exist.
+func NewPromptingAuthLoader(reader io.Reader) AuthLoader {
+	return &promptingAuthLoader{reader}
+}
+
+// NewDefaultAuthLoader returns a default implementation of an AuthLoader that only reads from a config file
+func NewDefaultAuthLoader() AuthLoader {
+	return &defaultAuthLoader{}
+}