Create kubernetes client

creating-kubernetes-client.md

To compile run:

mkdir [project]
cd [project]
export GO111MODULE=on
go mod init
go get k8s.io/[email protected]
[copy in main.go]
go build main.go
./main

main.go

// Note: the example only works with the code within the same release/branch.
package main

import (
	"flag"
	"fmt"
	"os"
	"path/filepath"

	"k8s.io/apimachinery/pkg/api/errors"
	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
	"k8s.io/client-go/kubernetes"
	"k8s.io/client-go/tools/clientcmd"
	"k8s.io/client-go/rest"
	//
	// Uncomment to load all auth plugins
	// _ "k8s.io/client-go/plugin/pkg/client/auth"
	//
	// Or uncomment to load specific auth plugins
	// _ "k8s.io/client-go/plugin/pkg/client/auth/azure"
	// _ "k8s.io/client-go/plugin/pkg/client/auth/gcp"
	// _ "k8s.io/client-go/plugin/pkg/client/auth/oidc"
	// _ "k8s.io/client-go/plugin/pkg/client/auth/openstack"
)

func main() {
	var kubeconfig *string
	var namespace *string
	if home := homeDir(); home != "" {
		kubeconfig = flag.String("kubeconfig", filepath.Join(home, ".kube", "config"), "(optional) absolute path to the kubeconfig file")
	} else {
		kubeconfig = flag.String("kubeconfig", "", "absolute path to the kubeconfig file")
	}
	namespace = flag.String("namespace", "default", "The namespace to list pods from")
	if namespace == nil {
		panic(fmt.Errorf("Unable to find null namespace"))
	}
	flag.Parse()

	// use the current context in kubeconfig
	config, err := clientcmd.BuildConfigFromFlags("", *kubeconfig)
	if err != nil {
		// See if we are in cluster if we fail to read a kube config.
		config, err = rest.InClusterConfig()
		if err != nil {
			panic(err.Error())
		}
	}

	// create the clientset
	clientset, err := kubernetes.NewForConfig(config)
	if err != nil {
		panic(err.Error())
	}
	
	pods, err := clientset.CoreV1().Pods("").List(metav1.ListOptions{})
	if err != nil {
		panic(err.Error())
	}
	fmt.Printf("There are %d pods in the cluster\n", len(pods.Items))

	// Examples for error handling:
	// - Use helper functions like e.g. errors.IsNotFound()
	// - And/or cast to StatusError and use its properties like e.g. ErrStatus.Message
	pods, err = clientset.CoreV1().Pods(*namespace).List(metav1.ListOptions{})
	if errors.IsNotFound(err) {
		fmt.Printf("Pods in namespace %s not found\n", *namespace)
	} else if statusError, isStatus := err.(*errors.StatusError); isStatus {
		fmt.Printf("Error getting pods in namespace %s: %v\n",
			*namespace, statusError.ErrStatus.Message)
	} else if err != nil {
		panic(err.Error())
	} else {
		fmt.Printf("Found pods in namespace %s\n", *namespace)
	}
	fmt.Printf("%#+v\n", pods);
}

func homeDir() string {
	if h := os.Getenv("HOME"); h != "" {
		return h
	}
	return os.Getenv("USERPROFILE") // windows
}