update demo

Signed-off-by: dragonflylee <dragonflylee@outlook.com>

tests/watch/watch.go

@@ -0,0 +1,55 @@
+package main
+
+import (
+	"context"
+	"flag"
+	"fmt"
+	"log"
+	"path/filepath"
+
+	corev1 "k8s.io/api/core/v1"
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+	"k8s.io/apimachinery/pkg/watch"
+	"k8s.io/client-go/kubernetes"
+	"k8s.io/client-go/tools/clientcmd"
+	"k8s.io/client-go/util/homedir"
+)
+
+func main() {
+	var kubeconfig string
+
+	flag.StringVar(&kubeconfig, "kubeconfig", filepath.Join(homedir.HomeDir(), ".kube", "config"), "(optional) absolute path to the kubeconfig file")
+	flag.Parse()
+	// use the current context in kubeconfig
+	config, err := clientcmd.BuildConfigFromFlags("", kubeconfig)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	ctx := context.Background()
+	// 创建 clientset
+	clientset, err := kubernetes.NewForConfig(config)
+	if err != nil {
+		log.Fatal(err)
+	}
+	// 使用 clientsent 监听 kube-system 下 Pod 对象
+	list, err := clientset.CoreV1().Pods("kube-system").
+		Watch(ctx, metav1.ListOptions{Watch: true})
+	if err != nil {
+		log.Fatal(err)
+	}
+	for event := range list.ResultChan() {
+		pod := event.Object.(*corev1.Pod)
+		switch event.Type {
+		case watch.Added:
+			fmt.Printf("Pod %s added\n", pod.Name)
+			// todo: reconcile logic goes here
+		case watch.Modified:
+			fmt.Printf("Pod %s modified\n", pod.Name)
+			// todo: reconcile logic goes here
+		case watch.Deleted:
+			fmt.Printf("Pod %s deleted\n", pod.Name)
+			// todo: reconcile logic goes here
+		}
+	}
+}