package main

import (
        "flag"
        "fmt"
        "os"
        metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
        "k8s.io/client-go/kubernetes"
        "k8s.io/client-go/rest"
        "k8s.io/client-go/tools/clientcmd"
)

func main() {
        kubeconfig := ""
        flag.StringVar(&kubeconfig, "kubeconfig", kubeconfig, "kubeconfig file")
        flag.Parse()
        
        if kubeconfig == "" {
                kubeconfig = os.Getenv("KUBECONFIG")
        }
        
        var (
                config *rest.Config
                err    error
        )
        
        if kubeconfig != "" {
                config, err = clientcmd.BuildConfigFromFlags("", kubeconfig)
        } else {
                config, err = rest.InClusterConfig()
        }
        if err != nil {
                fmt.Fprintf(os.Stderr, "error creating client: %v", err)
                os.Exit(1)
        }
        
        client := kubernetes.NewForConfigOrDie(config)
        
        list, err := client.CoreV1().Nodes().List(metav1.ListOptions{})
        if err != nil {
                fmt.Fprintf(os.Stderr, "error listing nodes: %v", err)
                os.Exit(1)
        }
        
        for _, node := range list.Items {
                fmt.Printf("Node: %s\n", node.Name)
        }
}