Revert vendor directory to support old golang (GOPATH mode)

gomodule is still in progress to migrate for now, hence multus
team decide to keep vendor directory to support build without
gomodule.

vendor/k8s.io/client-go/tools/clientcmd/auth_loaders.go

@@ -0,0 +1,111 @@
+/*
+Copyright 2014 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 clientcmd
+
+import (
+	"encoding/json"
+	"fmt"
+	"io"
+	"io/ioutil"
+	"os"
+
+	"golang.org/x/crypto/ssh/terminal"
+
+	clientauth "k8s.io/client-go/tools/auth"
+)
+
+// 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) {
+	// Prompt for user/pass and write a file if none exists.
+	if _, err := os.Stat(path); os.IsNotExist(err) {
+		authPtr, err := a.Prompt()
+		auth := *authPtr
+		if err != nil {
+			return nil, err
+		}
+		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
+}
+
+// Prompt pulls the user and password from a reader
+func (a *PromptingAuthLoader) Prompt() (*clientauth.Info, error) {
+	var err error
+	auth := &clientauth.Info{}
+	auth.User, err = promptForString("Username", a.reader, true)
+	if err != nil {
+		return nil, err
+	}
+	auth.Password, err = promptForString("Password", nil, false)
+	if err != nil {
+		return nil, err
+	}
+	return auth, nil
+}
+
+func promptForString(field string, r io.Reader, show bool) (result string, err error) {
+	fmt.Printf("Please enter %s: ", field)
+	if show {
+		_, err = fmt.Fscan(r, &result)
+	} else {
+		var data []byte
+		if terminal.IsTerminal(int(os.Stdin.Fd())) {
+			data, err = terminal.ReadPassword(int(os.Stdin.Fd()))
+			result = string(data)
+		} else {
+			return "", fmt.Errorf("error reading input for %s", field)
+		}
+	}
+	return result, err
+}
+
+// NewPromptingAuthLoader 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) *PromptingAuthLoader {
+	return &PromptingAuthLoader{reader}
+}
+
+// NewDefaultAuthLoader returns a default implementation of an AuthLoader that only reads from a config file
+func NewDefaultAuthLoader() AuthLoader {
+	return &defaultAuthLoader{}
+}