Go: What is Go and Kubernetes client-go?

1import (
2    "context"
3    "k8s.io/client-go/kubernetes"
4    "k8s.io/client-go/tools/clientcmd"
5    metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
6)
7
8func main() {
9    // Connect to cluster
10    kubeconfig, _ := clientcmd.BuildConfigFromFlags("",
11        filepath.Join(os.Getenv("HOME"), ".kube", "config"))
12
13    clientset, err := kubernetes.NewForConfig(kubeconfig)
14    if err != nil {
15        log.Fatal(err)
16    }
17
18    // Get pods
19    pods, err := clientset.CoreV1().Pods("default").List(
20        context.Background(),
21        metav1.ListOptions{},
22    )
23    if err != nil {
24        log.Fatal(err)
25    }
26
27    for _, pod := range pods.Items {
28        fmt.Printf("Pod: %s (Status: %s)\n", pod.Name, pod.Status.Phase)
29    }
30
31    // Create Deployment
32    deployment := &appsv1.Deployment{
33        ObjectMeta: metav1.ObjectMeta{
34            Name: "my-app",
35        },
36        Spec: appsv1.DeploymentSpec{
37            Replicas: int32Ptr(3),
38            Selector: &metav1.LabelSelector{
39                MatchLabels: map[string]string{"app": "my-app"},
40            },
41            Template: corev1.PodTemplateSpec{
42                ObjectMeta: metav1.ObjectMeta{
43                    Labels: map[string]string{"app": "my-app"},
44                },
45                Spec: corev1.PodSpec{
46                    Containers: []corev1.Container{{
47                        Name:  "app",
48                        Image: "my-app:latest",
49                    }},
50                },
51            },
52        },
53    }
54
55    _, err = clientset.AppsV1().Deployments("default").Create(
56        context.Background(), deployment, metav1.CreateOptions{})
57}
58
59// Watch: tracking changes
60watcher, _ := clientset.CoreV1().Pods("").Watch(
61    context.Background(),
62    metav1.ListOptions{})
63
64for event := range watcher.ResultChan() {
65    pod := event.Object.(*corev1.Pod)
66    fmt.Printf("Event: %s, Pod: %s\n", event.Type, pod.Name)
67}