clientset

Overview

Usage

deployments, err := clientset.AppsV1().Deployments("namespace").List(ctx, metav1.ListOptions{})

1. clientset has set of clients as the name indicates.
2. Get a specific client with AppsV1() for a group version.
3. Get deployment with Deployments() which has operation methods (e.g. Get, Update, Patch, List)

Example

List Pods with client-go v0.37.1. Run commands from the repository root. The default kubeconfig is ~/.kube/config; override it with -kubeconfig /path/to/config. Permission to list Pods across namespaces is required:

1. Get config

   config, err := clientcmd.BuildConfigFromFlags("", *kubeconfig)
   if err != nil {
       log.Fatal(err)
   }
   

2. Init clientset with config

   // NewForConfig creates a new Clientset for the given config.
   clientset, err := kubernetes.NewForConfig(config)
   if err != nil {
       log.Fatal(err)
   }
   

   Internally, call xxxx.NewForConfigAndClient to get a client for each group version.

3. Use the clientset to list Pods

   ctx, cancel := context.WithTimeout(context.Background(), 30*time.Second)
   defer cancel()
   pods, err := clientset.CoreV1().Pods(metav1.NamespaceAll).List(ctx, metav1.ListOptions{})
   if err != nil {
       log.Fatal(err)
   }
   

go run ./contents/kubernetes-operator/client-go/clientset
[Pod 0] kube-system/coredns-f9fd979d6-5n4pw
[Pod 1] kube-system/coredns-f9fd979d6-cp5pl
[Pod 2] kube-system/etcd-docker-desktop
[Pod 3] kube-system/kube-apiserver-docker-desktop
[Pod 4] kube-system/kube-controller-manager-docker-desktop
[Pod 5] kube-system/kube-proxy-8qp9g
[Pod 6] kube-system/kube-scheduler-docker-desktop
[Pod 7] kube-system/storage-provisioner
[Pod 8] kube-system/vpnkit-controller

The printed namespace/name depends on your cluster. Installing a CRD does not add it to this Clientset: use generated clients, the dynamic client, or controller-runtime's Client for custom resources.

Appendix