How do I create kube config file from rest.Config object?

[vadasambar]

I have rest.Config (https://godoc.org/k8s.io/client-go/rest#Config) object in my code. I want to write it to a kube config file to use it later. How would I go about writing it to a file?

[vadasambar]

I think I will need to convert my rest.Config to api.Config first.

[aayush-rangwala]

Following. Have similar use case, to convert rest config to kubeconfig file

[fejta-bot]

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[vadasambar]

Ultimately, it's about converting https://pkg.go.dev/k8s.io/client-go/rest?tab=doc#Config into https://pkg.go.dev/k8s.io/client-go/tools/clientcmd/api?tab=doc#Config

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[daxmc99]

This works

c, err := clientcmd.NewDefaultClientConfigLoadingRules().Load()
if err != nil {
	os.Exit(1)
}
clientConfig := clientcmd.NewDefaultClientConfig(*c, nil)
config, err = clientConfig.ClientConfig()

[Jordan396]

In my case, I had a rest.Config from the cluster administrator's kube config file, and I needed to generate a kube config file for a new user using api.Config. Following the bash script approach to generating a kube config file, I formatted the parameters of api.Config using fields extracted from the cluster api with the rest.config.

func (kc *KubeController) GenerateKubeConfiguration(namespace string) (string, error) {
	// Get secret list for namespace
	secretList, err := kc.clientset.CoreV1().Secrets(namespace).List(context.TODO(), metav1.ListOptions{})
	if err != nil {
		return "", err
	}

	// Get secret containing authentication data
	secret := secretList.Items[1]

	clusters := make(map[string]*clientcmdapi.Cluster)
	clusters["default-cluster"] = &clientcmdapi.Cluster{
		Server:                   kc.restconfig.Host,
		CertificateAuthorityData: secret.Data["ca.crt"],
	}

	contexts := make(map[string]*clientcmdapi.Context)
	contexts["default-context"] = &clientcmdapi.Context{
		Cluster:   "default-cluster",
		Namespace: namespace,
		AuthInfo:  namespace,
	}

	authinfos := make(map[string]*clientcmdapi.AuthInfo)
	authinfos[namespace] = &clientcmdapi.AuthInfo{
		Token: string(secret.Data["token"]),
	}

	clientConfig := clientcmdapi.Config{
		Kind:           "Config",
		APIVersion:     "v1",
		Clusters:       clusters,
		Contexts:       contexts,
		CurrentContext: "default-context",
		AuthInfos:      authinfos,
	}
	clientcmd.WriteToFile(clientConfig,  "/var/tmp/" + namespace + ".kubeconfig")
}

[OyutianO]

In my case, I had a rest.Config from the cluster administrator's kube config file, and I needed to generate a kube config file for a new user using api.Config. Following the bash script approach to generating a kube config file, I formatted the parameters of api.Config using fields extracted from the cluster api with the rest.config.

func (kc *KubeController) GenerateKubeConfiguration(namespace string) (string, error) {
	// Get secret list for namespace
	secretList, err := kc.clientset.CoreV1().Secrets(namespace).List(context.TODO(), metav1.ListOptions{})
	if err != nil {
		return "", err
	}

	// Get secret containing authentication data
	secret := secretList.Items[1]

	clusters := make(map[string]*clientcmdapi.Cluster)
	clusters["default-cluster"] = &clientcmdapi.Cluster{
		Server:                   kc.restconfig.Host,
		CertificateAuthorityData: secret.Data["ca.crt"],
	}

	contexts := make(map[string]*clientcmdapi.Context)
	contexts["default-context"] = &clientcmdapi.Context{
		Cluster:   "default-cluster",
		Namespace: namespace,
		AuthInfo:  namespace,
	}

	authinfos := make(map[string]*clientcmdapi.AuthInfo)
	authinfos[namespace] = &clientcmdapi.AuthInfo{
		Token: string(secret.Data["token"]),
	}

	clientConfig := clientcmdapi.Config{
		Kind:           "Config",
		APIVersion:     "v1",
		Clusters:       clusters,
		Contexts:       contexts,
		CurrentContext: "default-context",
		AuthInfos:      authinfos,
	}
	clientcmd.WriteToFile(clientConfig,  "/var/tmp/" + namespace + ".kubeconfig")
}

very useful!!!

[rainbowBPF2]

This works

c, err := clientcmd.NewDefaultClientConfigLoadingRules().Load()
if err != nil {
	os.Exit(1)
}
clientConfig := clientcmd.NewDefaultClientConfig(*c, nil)
config, err = clientConfig.ClientConfig()

I found a new way. Test ok~
var kubeconfig * string
// update kubeconfig content.

bytesArray := []byte(*kubeconfig)

clientConfig ,err:= clientcmd.NewClientConfigFromBytes(bytesArray)
if err!=nil {
	logs.Error(err.Error())
	return nil
}

restConfig, _ := clientConfig.ClientConfig()
clientSet, err := kubernetes.NewForConfig(restConfig)

[shamhub]

#1144

@Jordan396

[shamhub]

#1144

@rainbowBPF2

[ekesken]

just an easier way to create a kubeconfig file from the rest.Config coming from sigs.k8s.io/controller-runtime/pkg/envtestwhich is used in test suites generated by kubebuilder:

import (
	"os"

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


func CreateKubeconfigFileForRestConfig(restConfig rest.Config) string {
	clusters := make(map[string]*clientcmdapi.Cluster)
	clusters["default-cluster"] = &clientcmdapi.Cluster{
		Server:                   restConfig.Host,
		CertificateAuthorityData: restConfig.CAData,
	}
	contexts := make(map[string]*clientcmdapi.Context)
	contexts["default-context"] = &clientcmdapi.Context{
		Cluster:  "default-cluster",
		AuthInfo: "default-user",
	}
	authinfos := make(map[string]*clientcmdapi.AuthInfo)
	authinfos["default-user"] = &clientcmdapi.AuthInfo{
		ClientCertificateData: restConfig.CertData,
		ClientKeyData:         restConfig.KeyData,
	}
	clientConfig := clientcmdapi.Config{
		Kind:           "Config",
		APIVersion:     "v1",
		Clusters:       clusters,
		Contexts:       contexts,
		CurrentContext: "default-context",
		AuthInfos:      authinfos,
	}
	kubeConfigFile, _ := os.CreateTemp("", "kubeconfig")
	_ = clientcmd.WriteToFile(clientConfig, kubeConfigFile.Name())
	return kubeConfigFile.Name()
}

[delthas]

just an easier way to create a kubeconfig file from the rest.Config coming from sigs.k8s.io/controller-runtime/pkg/envtestwhich is used in test suites generated by kubebuilder:

This will only work on a rest.Config object having a cert and key data. The other way to do it by @Jordan396 above works on any rest.Config object (it just uses the API server host).