如何使用其客户端在kubernetes服务上观看事件

Question

我希望在使用client-go在kubernetes上更改服务时收到通知。

Answer 1

这可以这样做：

package main

import (
    "fmt"
    "flag"
    "time"

    "k8s.io/client-go/kubernetes"
    "k8s.io/client-go/pkg/api/v1"
    "k8s.io/client-go/tools/clientcmd"
    "k8s.io/client-go/tools/cache"
    "k8s.io/client-go/pkg/fields"
)

var (
    kubeconfig = flag.String("kubeconfig", "./config", "absolute path to the kubeconfig file")
)

func main() {
    flag.Parse()
    config, err := clientcmd.BuildConfigFromFlags("", *kubeconfig)
    if err != nil {
        panic(err.Error())
    }
    clientset, err := kubernetes.NewForConfig(config)
    if err != nil {
        panic(err.Error())
    }

    watchlist := cache.NewListWatchFromClient(clientset.Core().RESTClient(), "services", v1.NamespaceDefault,
        fields.Everything())
    _, controller := cache.NewInformer(
        watchlist,
        &v1.Service{},
        time.Second * 0,
        cache.ResourceEventHandlerFuncs{
            AddFunc: func(obj interface{}) {
                fmt.Printf("service added: %s \n", obj)
            },
            DeleteFunc: func(obj interface{}) {
                fmt.Printf("service deleted: %s \n", obj)
            },
            UpdateFunc:func(oldObj, newObj interface{}) {
                fmt.Printf("service changed \n")
            },
        },
    )
    stop := make(chan struct{})
    go controller.Run(stop)
    for{
        time.Sleep(time.Second)
    }
}

Answer 2

这是最新版本的client-go的用法示例。根据上面的代码。

package main

import (
    "fmt"
    "time"

     "github.com/golang/glog"

     "k8s.io/api/core/v1"
     "k8s.io/apimachinery/pkg/fields"
     "k8s.io/client-go/kubernetes"
     "k8s.io/client-go/tools/cache"
     "k8s.io/client-go/tools/clientcmd"
)

func main() {
    config, err := clientcmd.BuildConfigFromFlags("", "")
    if err != nil {
        glog.Errorln(err)
    }
    clientset, err := kubernetes.NewForConfig(config)
    if err != nil {
        glog.Errorln(err)
    }

    watchlist := cache.NewListWatchFromClient(
        clientset.CoreV1().RESTClient(),
        string(v1.ResourceServices),
        v1.NamespaceAll,
        fields.Everything(),
    )
    _, controller := cache.NewInformer( // also take a look at NewSharedIndexInformer
        watchlist,
        &v1.Service{},
        0, //Duration is int64
        cache.ResourceEventHandlerFuncs{
            AddFunc: func(obj interface{}) {
                fmt.Printf("service added: %s \n", obj)
            },
            DeleteFunc: func(obj interface{}) {
                fmt.Printf("service deleted: %s \n", obj)
            },
            UpdateFunc: func(oldObj, newObj interface{}) {
                fmt.Printf("service changed \n")
            },
         },
     )
         // I found it in k8s scheduler module. Maybe it's help if you 
    interested in.
     // serviceInformer := 
    cache.NewSharedIndexInformer(watchlist, 
     &v1.Service{}, 0, cache.Indexers{
     //     cache.NamespaceIndex: cache.MetaNamespaceIndexFunc,
     // })
     // go serviceInformer.Run(stop)
    stop := make(chan struct{})
    defer close(stop)
    go controller.Run(stop)
    for {
        time.Sleep(time.Second)
    }
}

Answer 3

这是使用SharedInformerFactory的简单方法。

package main

import (
    "fmt"
    "time"

    "github.com/golang/glog"

    kubeinformers "k8s.io/client-go/informers"
    "k8s.io/client-go/kubernetes"
    "k8s.io/client-go/tools/cache"
    "k8s.io/client-go/tools/clientcmd"
)

func main() {
    config, err := clientcmd.BuildConfigFromFlags("", "")
    if err != nil {
        glog.Errorln(err)
    }
    clientset, err := kubernetes.NewForConfig(config)
    if err != nil {
        glog.Errorln(err)
    }

    kubeInformerFactory := kubeinformers.NewSharedInformerFactory(clientset, time.Second*30)
    svcInformer := kubeInformerFactory.Core().V1().Services().Informer()

    svcInformer.AddEventHandler(cache.ResourceEventHandlerFuncs{
        AddFunc: func(obj interface{}) {
            fmt.Printf("service added: %s \n", obj)
        },
        DeleteFunc: func(obj interface{}) {
            fmt.Printf("service deleted: %s \n", obj)
        },
        UpdateFunc: func(oldObj, newObj interface{}) {
            fmt.Printf("service changed: %s \n", newObj)
        },
    },)

    stop := make(chan struct{})
    defer close(stop)
    kubeInformerFactory.Start(stop)
    for {
        time.Sleep(time.Second)
    }
}

Answer 4

package main

import (
    "fmt"
    "flag"
    "time"
    "log"

    "k8s.io/client-go/kubernetes"
    "k8s.io/client-go/pkg/api/v1"
    "k8s.io/client-go/tools/clientcmd"
    "k8s.io/client-go/tools/cache"
    "k8s.io/client-go/pkg/fields"
    metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
    "k8s.io/apimachinery/pkg/watch"
)

var (
    kubeconfig = flag.String("kubeconfig", "./config", "absolute path to the kubeconfig file")
)

func main() {
    flag.Parse()
    config, err := clientcmd.BuildConfigFromFlags("", *kubeconfig)
    if err != nil {
        log.Fatal(err.Error())
    }
    clientset, err := kubernetes.NewForConfig(config)
    if err != nil {
        log.Fatal(err.Error())
    }

    watcher, err := client.CoreV1().Services(v1.NamespaceDefault,).Watch(metav1.ListOptions{})
    if err != nil {
        log.Fatal(err)
    }

    for event := range watcher.ResultChan() {
        svc := event.Object.(*v1.Service)

        switch event.Type {
        case watch.Added:
           fmt.Printf("Service %s/%s added", svc.ObjectMeta.Namespace, svc.ObjectMeta.Name)
        case watch.Modified:
           fmt.Printf("Service %s/%s modified", svc.ObjectMeta.Namespace, svc.ObjectMeta.Name)
        case watch.Deleted:
           fmt.Printf("Service %s/%s deleted", svc.ObjectMeta.Namespace, svc.ObjectMeta.Name)
        }
    }

}