k8s源码学习-集群外的应用程序向k8s api身份认证（kubeconfig）

使用 client-go 配置客户端，使用包含集群上下文信息的 kubeconfig 文件来初始化客户端。以从在 Kubernetes 集群外部运行的应用程序向 Kubernetes API 进行身份验证。与kubectl命令使用 kubeconfig 文件对集群进行身份验证类似。

当前项目代码：​​代码参考​​

package main

import (
  "context"
  "flag"
  "fmt"
  "path/filepath"
  "time"

  "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/util/homedir"
)

func main() {
  var kubeconfig *string
  if home := homedir.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")
  }
  flag.Parse()

  // 使用kubeconfig中的当前上下文,加载配置文件
  config, err := clientcmd.BuildConfigFromFlags("", *kubeconfig)
  if err != nil {
    panic(err.Error())
  }

  // 创建clientset
  clientset, err := kubernetes.NewForConfig(config)
  if err != nil {
    panic(err.Error())
  }
        // 遍历pods,list获取pod的数量
  for {
    pods, err := clientset.CoreV1().Pods("").List(context.TODO(), metav1.ListOptions{})
    if err != nil {
      panic(err.Error())
    }
    fmt.Printf("There are %d pods in the cluster\n", len(pods.Items))

                //错误处理的例子:
                // -使用helper函数，如errors.IsNotFound()
                // -和/或转换为StatusError，并使用它的属性，如ErrStatus.Message                

    namespace := "default"
    pod := "test-node-local-dns"
    _, err = clientset.CoreV1().Pods(namespace).Get(context.TODO(), pod, metav1.GetOptions{})
    if errors.IsNotFound(err) {
      fmt.Printf("Pod %s in namespace %s not found\n", pod, namespace)
    } else if statusError, isStatus := err.(*errors.StatusError); isStatus {
      fmt.Printf("Error getting pod %s in namespace %s: %v\n",
        pod, namespace, statusError.ErrStatus.Message)
    } else if err != nil {
      panic(err.Error())
    } else {
      fmt.Printf("Found pod %s in namespace %s\n", pod, namespace)
    }

    time.Sleep(10 * time.Second)
  }
}

➜  client-go-k8s-cluster-external git:(master) ✗ ls
README.md go.mod    go.sum    main.go

运行​​go​​项目

➜  client-go-k8s-cluster-external git:(master) ✗ go run main.go
There are 13 pods in the cluster
Pod test-node-local-dns in namespace default not found