add kubeconfig file

pkg/client/clientcmd/loader.go

@@ -0,0 +1,117 @@
+/*
+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 (
+	"io/ioutil"
+	"os"
+
+	"github.com/imdario/mergo"
+	"gopkg.in/v2/yaml"
+)
+
+const (
+	RecommendedConfigPathFlag   = "kubeconfig"
+	RecommendedConfigPathEnvVar = "KUBECONFIG"
+)
+
+// ClientConfigLoadingRules is a struct that calls our specific locations that are used for merging together a Config
+type ClientConfigLoadingRules struct {
+	CommandLinePath      string
+	EnvVarPath           string
+	CurrentDirectoryPath string
+	HomeDirectoryPath    string
+}
+
+// NewClientConfigLoadingRules returns a ClientConfigLoadingRules object with default fields filled in.  You are not required to
+// use this constructor
+func NewClientConfigLoadingRules() *ClientConfigLoadingRules {
+	return &ClientConfigLoadingRules{
+		CurrentDirectoryPath: ".kubeconfig",
+		HomeDirectoryPath:    os.Getenv("HOME") + "/.kube/.kubeconfig",
+	}
+}
+
+// Load takes the loading rules and merges together a Config object based on following order.
+//   1.  CommandLinePath
+//   2.  EnvVarPath
+//   3.  CurrentDirectoryPath
+//   4.  HomeDirectoryPath
+// Empty filenames are ignored.  Files with non-deserializable content produced errors.
+// The first file to set a particular value or map key wins and the value or map key is never changed.
+// This means that the first file to set CurrentContext will have its context preserved.  It also means
+// that if two files specify a "red-user", only values from the first file's red-user are used.  Even
+// non-conflicting entries from the second file's "red-user" are discarded.
+func (rules *ClientConfigLoadingRules) Load() (*Config, error) {
+	config := NewConfig()
+
+	mergeConfigWithFile(config, rules.CommandLinePath)
+	mergeConfigWithFile(config, rules.EnvVarPath)
+	mergeConfigWithFile(config, rules.CurrentDirectoryPath)
+	mergeConfigWithFile(config, rules.HomeDirectoryPath)
+
+	return config, nil
+}
+
+func mergeConfigWithFile(startingConfig *Config, filename string) error {
+	if len(filename) == 0 {
+		// no work to do
+		return nil
+	}
+
+	config, err := LoadFromFile(filename)
+	if err != nil {
+		return err
+	}
+
+	mergo.Merge(startingConfig, config)
+
+	return nil
+}
+
+// LoadFromFile takes a filename and deserializes the contents into Config object
+func LoadFromFile(filename string) (*Config, error) {
+	config := &Config{}
+
+	kubeconfigBytes, err := ioutil.ReadFile(filename)
+	if err != nil {
+		return nil, err
+	}
+
+	err = yaml.Unmarshal(kubeconfigBytes, &config)
+	if err != nil {
+		return nil, err
+	}
+
+	return config, nil
+}
+
+// WriteToFile serializes the config to yaml and writes it out to a file.  If no present, it creates the file with 0644.  If it is present
+// it stomps the contents
+func WriteToFile(config Config, filename string) error {
+	content, err := yaml.Marshal(config)
+	if err != nil {
+		return err
+	}
+
+	err = ioutil.WriteFile(filename, content, 0644)
+	if err != nil {
+		return err
+	}
+
+	return nil
+}