package main

import (

  "flag"

  "fmt"

  "path/filepath"

  "time"

  v1 "k8s.io/api/apps/v1"

  "k8s.io/apimachinery/pkg/labels"

  "k8s.io/client-go/informers"

  "k8s.io/client-go/kubernetes"

  "k8s.io/client-go/rest"

  "k8s.io/client-go/tools/cache"

  "k8s.io/client-go/tools/clientcmd"

  "k8s.io/client-go/util/homedir"

)

func main() {

  var err error

  var config *rest.Config

  var kubeconfig *string

  if home := homedir.HomeDir(); home != "" {

    kubeconfig = flag.String("kubeconfig", filepath.Join(home, ".kube", "config"), "[可选] kubeconfig 绝对路径")

  } else {

    kubeconfig = flag.String("kubeconfig", "", "kubeconfig 绝对路径")

  }

  // 初始化 rest.Config 对象

  if config, err = rest.InClusterConfig(); err != nil {

    if config, err = clientcmd.BuildConfigFromFlags("", *kubeconfig); err != nil {

      panic(err.Error())

    }

  }

  // 创建 Clientset 对象

  clientset, err := kubernetes.NewForConfig(config)

  if err != nil {

    panic(err.Error())

  }

  // 初始化 informer factory（为了测试方便这里设置每30s重新 List 一次）

  informerFactory := informers.NewSharedInformerFactory(clientset, time.Second*)

  // 对 Deployment 监听

  deployInformer := informerFactory.Apps().V1().Deployments()

  // 创建 Informer（相当于注册到工厂中去，这样下面启动的时候就会去 List & Watch 对应的资源）

  informer := deployInformer.Informer()

  // 创建 Lister

  deployLister := deployInformer.Lister()

  // 注册事件处理程序

  informer.AddEventHandler(cache.ResourceEventHandlerFuncs{

    AddFunc:    onAdd,

    UpdateFunc: onUpdate,

    DeleteFunc: onDelete,

  })

  stopper := make(chan struct{})

  defer close(stopper)

  // 启动 informer，List & Watch

  informerFactory.Start(stopper)

  // 等待所有启动的 Informer 的缓存被同步

  informerFactory.WaitForCacheSync(stopper)

  // 从本地缓存中获取 default 中的所有 deployment 列表

  deployments, err := deployLister.Deployments("default").List(labels.Everything())

  if err != nil {

    panic(err)

  }

  for idx, deploy := range deployments {

    fmt.Printf("%d -> %s\n", idx+, deploy.Name)

  }

  <-stopper

}

func onAdd(obj interface{}) {

  deploy := obj.(*v1.Deployment)

  fmt.Println("add a deployment:", deploy.Name)

}

func onUpdate(old, new interface{}) {

  oldDeploy := old.(*v1.Deployment)

  newDeploy := new.(*v1.Deployment)

  fmt.Println("update deployment:", oldDeploy.Name, newDeploy.Name)

}

func onDelete(obj interface{}) {

  deploy := obj.(*v1.Deployment)

  fmt.Println("delete a deployment:", deploy.Name)

}

$ go run main.go

add a deployment: dingtalk-hook

add a deployment: spin-orca

add a deployment: argocd-server

add a deployment: istio-egressgateway

add a deployment: vault-agent-injector

add a deployment: rook-ceph-osd-

add a deployment: rook-ceph-osd-

add a deployment: code-server

......

 -> nginx

 -> helloworld-v1

 -> productpage-v1

 -> details-v1

......