How to watch events on the kubernetes service using your go client

Question

I would like to receive information when the service on quartets using client-go has ever been changed.

Answer 1

this can be done as follows:

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

This is the latest version of a client use case. According to the code above.

 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 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

It is simple using a 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) } }