How to watch events on a kubernetes service using its go client

Question

I would like to be informed when ever a service is changed on kubernetes using client-go.

Answer 1

This is a simple one using SharedInformerFactory.

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)
    }
}