Kubernetes cluster ID

main.go

package main

import (
	"context"
	"fmt"
	"log"
	"os"
	"path/filepath"

	"github.com/google/uuid"
	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
	"k8s.io/client-go/kubernetes"
	"k8s.io/client-go/rest"
	"k8s.io/client-go/tools/clientcmd"
)

const (
	LABEL = "kube-system"
)

func main() {
	kubeConfig, err := SetConfig()
	if err != nil {
		log.Fatalf("error getting Kubernetes kubeConfig: %v\n", err)
	}

	clientset, err := NewClientset(kubeConfig)
	if err != nil {
		log.Fatalf("error init Kubernetes clientset: %v\n", err)
	}

	id, err := GetKubernetesClusterID(clientset)
	if err != nil {
		log.Fatalf("Can't fetch Kubernetes cluster id: %s", err)
	}
	fmt.Printf("%#v \n", id)
}

func SetConfig() (*rest.Config, error) {
	env := getEnv("ENV", "develop")
	var kubeConfig *rest.Config

	if env == "develop" {

		userHomeDir, err := os.UserHomeDir()
		if err != nil {
			return &rest.Config{}, err
		}
		kubeConfigPath := filepath.Join(userHomeDir, ".kube", "config")

		kubeConfig, err = clientcmd.BuildConfigFromFlags("", kubeConfigPath)
		if err != nil {
			return &rest.Config{}, err
		}
	} else {
		var err error
		kubeConfig, err = rest.InClusterConfig()
		if err != nil {
			return &rest.Config{}, err
		}
	}
	return kubeConfig, nil
}

func getEnv(key, def string) string {
	value, exists := os.LookupEnv(key)
	if !exists {
		value = def
	}
	return value
}

func NewClientset(kConfig *rest.Config) (*kubernetes.Clientset, error) {
	clientset, err := kubernetes.NewForConfig(kConfig)
	if err != nil {
		return &kubernetes.Clientset{}, err
	}

	return clientset, nil
}

func GetKubernetesClusterID(clientset *kubernetes.Clientset) (uuid.UUID, error) {
	var id uuid.UUID

	listOptions := metav1.ListOptions{
		LabelSelector: fmt.Sprintf("kubernetes.io/metadata.name=%s", LABEL),
	}
	namespaces, err := clientset.CoreV1().Namespaces().List(context.Background(), listOptions)
	if err != nil {
		return uuid.UUID{}, err
	}

	id, err = uuid.Parse(string(namespaces.Items[0].GetUID()))
	if err != nil {
		return uuid.UUID{}, err
	}

	return id, nil
}