import (
    "fmt"
    "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"
)

func demo(config *rest.Config, namespace string) {
    clientset, err := kubernetes.NewForConfig(config)
    if err != nil {
        panic(err)
    }

    informerFactory := informers.NewSharedInformerFactory(clientset, time.Minute)
    informer := informerFactory.Apps().V1().Deployments()
    informer.Informer().AddEventHandler(
        cache.ResourceEventHandlerFuncs{
            AddFunc:    onAdd,
            UpdateFunc: onUpdate,
            DeleteFunc: onDelete,
        })
    lister := informer.Lister()

    stopCh := make(chan struct{})
    defer close(stopCh)
    informerFactory.Start(stopCh)
    if !cache.WaitForCacheSync(stopCh, informer.Informer().HasSynced) {
        return
    }

    deployments, err := lister.Deployments(namespace).List(labels.Everything())
    if err != nil {
        panic(err)
    }
    for _, deployment := range deployments {
        fmt.Printf("%s\r\n", deployment.Name)
    }
    <-stopCh
}

func onAdd(obj interface{}) {
    deployment := obj.(*v1.Deployment)
    fmt.Printf("onAdd:%s\r\n", deployment.Name)
}

func onUpdate(old, new interface{}) {
    oldDeployment := old.(*v1.Deployment)
    newDeployment := new.(*v1.Deployment)
    fmt.Printf("onUpdate:%s to %s\r\n", oldDeployment.Name, newDeployment.Name)
}

func onDelete(obj interface{}) {
    deployment := obj.(*v1.Deployment)
    fmt.Printf("onDelete:%s\r\n", deployment.Name)
}