I would like to be informed when ever a service is changed on kubernetes using client-go.
this can be done like this:
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)
}
}
This is the latest version client-go's usage example. According the above code.
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)
}
}
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)
}
}