informer实现类似k8s watch机制|ifbiu blog

```golang
package main

import (
	"flag"
	"fmt"
	corev1 "k8s.io/api/core/v1"
	"k8s.io/apimachinery/pkg/labels"
	"k8s.io/client-go/informers"
	"k8s.io/client-go/kubernetes"
	"k8s.io/client-go/kubernetes/scheme"
	"k8s.io/client-go/tools/cache"
	"k8s.io/client-go/tools/clientcmd"
	"time"
)

func main() {
	kubeconfig := flag.String("kubeconfig", "/home/candide/.kube/config", "absolute path to the kubeconfig file")
	config, err := clientcmd.BuildConfigFromFlags("", *kubeconfig)
	if err != nil {
		fmt.Println("Error building config from flags:", err)
	}
	config.APIPath = "api"
	config.GroupVersion = &corev1.SchemeGroupVersion
	config.NegotiatedSerializer = scheme.Codecs

clientSet, err := kubernetes.NewForConfig(config)
	if err != nil {
		fmt.Println("Error building clientSet from flags:", err)
	}
	informerFactory := informers.NewSharedInformerFactory(clientSet, time.Minute)
	deploymentInformer := informerFactory.Apps().V1().Deployments()
	informer := deploymentInformer.Informer()
	deployLister := deploymentInformer.Lister()
	informer.AddEventHandler(cache.ResourceEventHandlerFuncs{
		AddFunc: func(obj interface{}) {
			fmt.Println("Deployment Added")
		},
		UpdateFunc: func(old, new interface{}) {
			fmt.Println("Deployment Updated")
		},
		DeleteFunc: func(obj interface{}) {
			fmt.Println("Deployment Deleted")
		},
	})
	serviceInformer := informerFactory.Core().V1().Services()
	informer = serviceInformer.Informer()
	//serviceLister := serviceInformer.Lister()
	informer.AddEventHandler(cache.ResourceEventHandlerFuncs{
		AddFunc: func(obj interface{}) {
			fmt.Println("Service Added")
		},
		UpdateFunc: func(old, new interface{}) {
			fmt.Println("Service Updated")
		},
		DeleteFunc: func(obj interface{}) {
			fmt.Println("Service Deleted")
		},
	})

stopper := make(chan struct{})
	defer close(stopper)

// Start informer, List & Watch
	informerFactory.Start(stopper)
	informerFactory.WaitForCacheSync(stopper)
	deployments, err := deployLister.Deployments("kube-system").List(labels.Everything())
	if err != nil {
		fmt.Println("Error listing deployments:", err)
	}
	for idx, deploy := range deployments {
		fmt.Println(idx, deploy.Name)
	}
	<-stopper
}

```