K8s client-go watch pod

一.前言#

我们在使用 kubectl 操作 k8s 时，可以在命令中加入 -w来观察资源变化，比如 kubectl get pod -w 观察 pod 状态变化。出了使用控制台，还可以编写代码和 k8s 交互来获取 pod 变更。

二.代码实现#

k8s client-go：https://github.com/kubernetes/client-go

安装 package: go get k8s.io/client-go

config, err := clientcmd.BuildConfigFromFlags("", filepath.Join(os.Getenv("HOME"), ".kube", "config"))
if err != nil {
	log.Fatal(err)
}

// 创建 client
clientSet, err := kubernetes.NewForConfig(config)
if err != nil {
	log.Fatal(err)
}

factory := informers.NewSharedInformerFactoryWithOptions(clientSet, 0, informers.WithNamespace("default"))
informer := factory.Core().V1().Pods().Informer()
informer.AddEventHandler(NewEventHandler())

stopper := make(chan struct{}, 2)
go informer.Run(stopper)
log.Println("watch pod started...")

sigs := make(chan os.Signal, 1)
signal.Notify(sigs, syscall.SIGINT, syscall.SIGTERM)

<-sigs
stopper <- struct{}{}
close(stopper)
log.Println("watch pod stopped...")

处理程序：

type EventHandler struct {
}

func NewEventHandler() *EventHandler {
	return &EventHandler{}
}

func (e *EventHandler) OnAdd(obj interface{}) {
	event := obj.(*corev1.Pod)
	log.Printf("OnAdd: %s", event.ObjectMeta.Name)
}

func (e *EventHandler) OnUpdate(oldObj, newObj interface{}) {
	event := newObj.(*corev1.Pod)
	log.Printf("OnUpdate: %s", event.ObjectMeta.Name)

}

func (e *EventHandler) OnDelete(obj interface{}) {
	event := obj.(*corev1.Pod)
	log.Printf("OnDelete: %s", event.ObjectMeta.Name)

}