kubeconfig.go

/*
Copyright 2017 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 kubeconfig

import (
	"fmt"

	clientset "k8s.io/client-go/kubernetes"
	"k8s.io/client-go/tools/clientcmd"
	clientcmdapi "k8s.io/client-go/tools/clientcmd/api"
)

// CreateBasic creates a basic, general KubeConfig object that then can be extended
func CreateBasic(serverURL string, clusterName string, userName string, caCert []byte) *clientcmdapi.Config {
	// Use the cluster and the username as the context name
	contextName := fmt.Sprintf("%s@%s", userName, clusterName)

	return &clientcmdapi.Config{
		Clusters: map[string]*clientcmdapi.Cluster{
			clusterName: {
				Server: serverURL,
				CertificateAuthorityData: caCert,
			},
		},
		Contexts: map[string]*clientcmdapi.Context{
			contextName: {
				Cluster:  clusterName,
				AuthInfo: userName,
			},
		},
		AuthInfos:      map[string]*clientcmdapi.AuthInfo{},
		CurrentContext: contextName,
	}
}

// CreateWithCerts creates a KubeConfig object with access to the API server with client certificates
func CreateWithCerts(serverURL, clusterName, userName string, caCert []byte, clientKey []byte, clientCert []byte) *clientcmdapi.Config {
	config := CreateBasic(serverURL, clusterName, userName, caCert)
	config.AuthInfos[userName] = &clientcmdapi.AuthInfo{
		ClientKeyData:         clientKey,
		ClientCertificateData: clientCert,
	}
	return config
}

// CreateWithToken creates a KubeConfig object with access to the API server with a token
func CreateWithToken(serverURL, clusterName, userName string, caCert []byte, token string) *clientcmdapi.Config {
	config := CreateBasic(serverURL, clusterName, userName, caCert)
	config.AuthInfos[userName] = &clientcmdapi.AuthInfo{
		Token: token,
	}
	return config
}

// ClientSetFromFile returns a ready-to-use client from a KubeConfig file
func ClientSetFromFile(path string) (*clientset.Clientset, error) {
	config, err := clientcmd.LoadFromFile(path)
	if err != nil {
		return nil, fmt.Errorf("failed to load admin kubeconfig [%v]", err)
	}
	return KubeConfigToClientSet(config)
}

// KubeConfigToClientSet converts a KubeConfig object to a client
func KubeConfigToClientSet(config *clientcmdapi.Config) (*clientset.Clientset, error) {
	clientConfig, err := clientcmd.NewDefaultClientConfig(*config, &clientcmd.ConfigOverrides{}).ClientConfig()
	if err != nil {
		return nil, fmt.Errorf("failed to create API client configuration from kubeconfig: %v", err)
	}

	client, err := clientset.NewForConfig(clientConfig)
	if err != nil {
		return nil, fmt.Errorf("failed to create API client: %v", err)
	}
	return client, nil
}

// WriteToDisk writes a KubeConfig object down to disk with mode 0600
func WriteToDisk(filename string, kubeconfig *clientcmdapi.Config) error {
	err := clientcmd.WriteToFile(*kubeconfig, filename)
	if err != nil {
		return err
	}

	fmt.Printf("[kubeconfig] Wrote KubeConfig file to disk: %q\n", filename)
	return nil
}

// GetClusterFromKubeConfig returns the default Cluster of the specified KubeConfig
func GetClusterFromKubeConfig(config *clientcmdapi.Config) *clientcmdapi.Cluster {
	// If there is an unnamed cluster object, use it
	if config.Clusters[""] != nil {
		return config.Clusters[""]
	}
	if config.Contexts[config.CurrentContext] != nil {
		return config.Clusters[config.Contexts[config.CurrentContext].Cluster]
	}
	return nil
}