SharedInformerFactoryWithOptions – Not able to filter based on labels

Issue

I want to watch Kubernetes pod events for a certain application.

I went with NewSharedInformerFactoryWithOptions. I have added appropriate labels selector, But it is not getting filtered out. As I want to filter it using the label: ‘app=nats-box’

Here is the code –

req, err := labels.NewRequirement("app", selection.Equals, []string{"nats-box"})
    if err != nil {
        log.Fatalf("error %s, bad requirement", err.Error())
    }
selector := labels.NewSelector()
selector.Add(*req)

filteredFactory := informers.NewSharedInformerFactoryWithOptions(clientset, 0, informers.WithNamespace("default"), informers.WithTweakListOptions(func(options *metav1.ListOptions) {
    options.LabelSelector = selector.String()
}))

podInformer := filteredFactory.Core().V1().Pods().Informer()

podInformer.AddEventHandler(cache.ResourceEventHandlerFuncs{
    AddFunc: func(obj interface{}) {
        fmt.Println("pod add")
        name := obj.(*corev1.Pod).Name
        labels := obj.(*corev1.Pod).Labels
        fmt.Printf("pod Name: %s\nLabels - %v\n\n", name, labels)
    })

I get the output for all the pods, the namespace is getting filtered but not the labels. Not able to figure out where I am making the mistake.

Solution

You can directly provide the label string in the opts.LabelSelector:

labelOptions := informers.WithTweakListOptions(func(opts *metav1.ListOptions) {
    opts.LabelSelector = "app=nats-box"
})
factory := informers.NewSharedInformerFactoryWithOptions(clientset, 0, informers.WithNamespace("default") ,labelOptions)
informer := factory.Core().V1().Pods().Informer()
stopper := make(chan struct{})
defer close(stopper)
informer.AddEventHandler(cache.ResourceEventHandlerFuncs{
    AddFunc: func(obj interface{}) {
        fmt.Println("pod add")
        name := obj.(*corev1.Pod).Name
        labels := obj.(*corev1.Pod).Labels
        fmt.Printf("pod Name: %s\nLabels - %v\n\n", name, labels)
    },
})
informer.Run(stopper)

Answered By – Theofilos Papapanagiotou

Answer Checked By – Dawn Plyler (GoLangFix Volunteer)

Leave a Reply

Your email address will not be published.