add utility for binding flags and building api server clients

pkg/client/clientcmd/client_builder.go

@@ -0,0 +1,181 @@
+/*
+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 (
+	"fmt"
+	"os"
+	"reflect"
+
+	"github.com/spf13/pflag"
+
+	"github.com/GoogleCloudPlatform/kubernetes/pkg/api/latest"
+	"github.com/GoogleCloudPlatform/kubernetes/pkg/client"
+	"github.com/GoogleCloudPlatform/kubernetes/pkg/clientauth"
+	"github.com/GoogleCloudPlatform/kubernetes/pkg/version"
+)
+
+// Builder are used to bind and interpret command line flags to make it easy to get an api server client
+type Builder interface {
+	// BindFlags must bind and keep track of all the flags required to build a client config object
+	BindFlags(flags *pflag.FlagSet)
+	// Config uses the values of the bound flags and builds a complete client config
+	Config() (*client.Config, error)
+	// Client calls BuildConfig under the covers and uses that config to return a client
+	Client() (*client.Client, error)
+}
+
+// cmdAuthInfo is used to track whether flags have been set
+type cmdAuthInfo struct {
+	User        StringFlag
+	Password    StringFlag
+	CAFile      StringFlag
+	CertFile    StringFlag
+	KeyFile     StringFlag
+	BearerToken StringFlag
+	Insecure    BoolFlag
+}
+
+// builder is a default implementation of a Builder
+type builder struct {
+	authLoader      AuthLoader
+	cmdAuthInfo     cmdAuthInfo
+	authPath        string
+	apiserver       string
+	apiVersion      string
+	matchApiVersion bool
+}
+
+// NewBuilder returns a valid Builder that uses the passed authLoader.  If authLoader is nil, the NewDefaultAuthLoader is used.
+func NewBuilder(authLoader AuthLoader) Builder {
+	if authLoader == nil {
+		authLoader = NewDefaultAuthLoader()
+	}
+
+	return &builder{
+		authLoader: authLoader,
+	}
+}
+
+const (
+	FlagApiServer       = "server"
+	FlagMatchApiVersion = "match-server-version"
+	FlagApiVersion      = "api-version"
+	FlagAuthPath        = "auth-path"
+	FlagInsecure        = "insecure-skip-tls-verify"
+	FlagCertFile        = "client-certificate"
+	FlagKeyFile         = "client-key"
+	FlagCAFile          = "certificate-authority"
+	FlagBearerToken     = "token"
+)
+
+// BindFlags implements Builder
+func (builder *builder) BindFlags(flags *pflag.FlagSet) {
+	flags.StringVarP(&builder.apiserver, FlagApiServer, "s", builder.apiserver, "The address of the Kubernetes API server")
+	flags.BoolVar(&builder.matchApiVersion, FlagMatchApiVersion, false, "Require server version to match client version")
+	flags.StringVar(&builder.apiVersion, FlagApiVersion, latest.Version, "The API version to use when talking to the server")
+	flags.StringVarP(&builder.authPath, FlagAuthPath, "a", os.Getenv("HOME")+"/.kubernetes_auth", "Path to the auth info file. If missing, prompt the user. Only used if using https.")
+	flags.Var(&builder.cmdAuthInfo.Insecure, FlagInsecure, "If true, the server's certificate will not be checked for validity. This will make your HTTPS connections insecure.")
+	flags.Var(&builder.cmdAuthInfo.CertFile, FlagCertFile, "Path to a client key file for TLS.")
+	flags.Var(&builder.cmdAuthInfo.KeyFile, FlagKeyFile, "Path to a client key file for TLS.")
+	flags.Var(&builder.cmdAuthInfo.CAFile, FlagCAFile, "Path to a cert. file for the certificate authority.")
+	flags.Var(&builder.cmdAuthInfo.BearerToken, FlagBearerToken, "Bearer token for authentication to the API server.")
+}
+
+// Client implements Builder
+func (builder *builder) Client() (*client.Client, error) {
+	clientConfig, err := builder.Config()
+	if err != nil {
+		return nil, err
+	}
+
+	c, err := client.New(clientConfig)
+	if err != nil {
+		return nil, err
+	}
+
+	if builder.matchApiVersion {
+		clientVersion := version.Get()
+		serverVersion, err := c.ServerVersion()
+		if err != nil {
+			return nil, fmt.Errorf("couldn't read version from server: %v\n", err)
+		}
+		if s := *serverVersion; !reflect.DeepEqual(clientVersion, s) {
+			return nil, fmt.Errorf("server version (%#v) differs from client version (%#v)!\n", s, clientVersion)
+		}
+	}
+
+	return c, nil
+}
+
+// Config implements Builder
+func (builder *builder) Config() (*client.Config, error) {
+	clientConfig := client.Config{}
+	if len(builder.apiserver) > 0 {
+		clientConfig.Host = builder.apiserver
+	} else if len(os.Getenv("KUBERNETES_MASTER")) > 0 {
+		clientConfig.Host = os.Getenv("KUBERNETES_MASTER")
+	} else {
+		// TODO: eventually apiserver should start on 443 and be secure by default
+		clientConfig.Host = "http://localhost:8080"
+	}
+	clientConfig.Version = builder.apiVersion
+
+	// only try to read the auth information if we are secure
+	if client.IsConfigTransportTLS(&clientConfig) {
+		authInfoFileFound := true
+		authInfo, err := builder.authLoader.LoadAuth(builder.authPath)
+		if authInfo == nil && err != nil { // only consider failing if we don't have any auth info
+			if os.IsNotExist(err) { // if it's just a case of a missing file, simply flag the auth as not found and use the command line arguments
+				authInfoFileFound = false
+				authInfo = &clientauth.Info{}
+			} else {
+				return nil, err
+			}
+		}
+
+		// If provided, the command line options override options from the auth file
+		if !authInfoFileFound || builder.cmdAuthInfo.User.Provided() {
+			authInfo.User = builder.cmdAuthInfo.User.Value
+		}
+		if !authInfoFileFound || builder.cmdAuthInfo.Password.Provided() {
+			authInfo.Password = builder.cmdAuthInfo.Password.Value
+		}
+		if !authInfoFileFound || builder.cmdAuthInfo.CAFile.Provided() {
+			authInfo.CAFile = builder.cmdAuthInfo.CAFile.Value
+		}
+		if !authInfoFileFound || builder.cmdAuthInfo.CertFile.Provided() {
+			authInfo.CertFile = builder.cmdAuthInfo.CertFile.Value
+		}
+		if !authInfoFileFound || builder.cmdAuthInfo.KeyFile.Provided() {
+			authInfo.KeyFile = builder.cmdAuthInfo.KeyFile.Value
+		}
+		if !authInfoFileFound || builder.cmdAuthInfo.BearerToken.Provided() {
+			authInfo.BearerToken = builder.cmdAuthInfo.BearerToken.Value
+		}
+		if !authInfoFileFound || builder.cmdAuthInfo.Insecure.Provided() {
+			authInfo.Insecure = &builder.cmdAuthInfo.Insecure.Value
+		}
+
+		clientConfig, err = authInfo.MergeWithConfig(clientConfig)
+		if err != nil {
+			return nil, err
+		}
+	}
+
+	return &clientConfig, nil
+}