【Kubernetes】client-goを利用してGolangからKubernetesのPod一覧を取得するサンプル

kubectlを利用する場合

aws eks update-kubeconfig --name vamdemic-development-eks-cluster

kube-systemのnamespaceでは、12のPodが起動中

yuta:~/go-kubernentes (master *+=) $ kubectl get pod -n kube-system 
NAME                                      READY   STATUS    RESTARTS   AGE
alb-ingress-controller-5b4b5fd775-8vxt7   1/1     Running   1          16d
aws-node-829mc                            1/1     Running   0          16d
aws-node-q4d67                            1/1     Running   0          16d
coredns-79769ff86-h2tck                   1/1     Running   0          16d
coredns-79769ff86-wclkd                   1/1     Running   0          16d
ebs-csi-controller-587cb4db9b-6j8xz       4/4     Running   3          16d
ebs-csi-controller-587cb4db9b-w5s5s       4/4     Running   2          16d
ebs-csi-node-gbpx4                        3/3     Running   0          16d
ebs-csi-node-l8rx5                        3/3     Running   0          16d
efs-csi-node-v6m4m                        3/3     Running   0          16d
efs-csi-node-vtf5r                        3/3     Running   0          16d
kube-proxy-7gbmn                          1/1     Running   0          16d
kube-proxy-8h4tk                          1/1     Running   0          16d

GoでPod一覧を取得する場合

package main

import (
    "context"
    "fmt"
    metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
    "k8s.io/client-go/kubernetes"
    "k8s.io/client-go/tools/clientcmd"
    "log"
    "os"
    "path/filepath"
)

func main() {
    // Kubeconfigのファイルパスを指定
    kubeconfig := filepath.Join(os.Getenv("HOME"), ".kube", "config")
    config, err := clientcmd.BuildConfigFromFlags("", kubeconfig)
    if err != nil {
        log.Fatal(err)
    }

    // Kubeconfigを読み込む
    clientset, err := kubernetes.NewForConfig(config)
    if err != nil {
        log.Fatal(err)
    }

    // Pod一覧を呼び出す
    namespace := "kube-system"
    pods, err := clientset.CoreV1().Pods(namespace).List(context.TODO(), metav1.ListOptions{})
    if err != nil {
        log.Fatalln("failed to get pods:", err)
    }

    // print pods
    // pods.Items: []v1.Pod
    for i, pod := range pods.Items {
        fmt.Printf("[%d] %s\n", i, pod.GetName())
    }
}

出力結果

yuta:~/go-kubernentes (master *+=) $ go run main.go 
[0] alb-ingress-controller-5b4b5fd775-8vxt7
[1] aws-node-829mc
[2] aws-node-q4d67
[3] coredns-79769ff86-h2tck
[4] coredns-79769ff86-wclkd
[5] ebs-csi-controller-587cb4db9b-6j8xz
[6] ebs-csi-controller-587cb4db9b-w5s5s
[7] ebs-csi-node-gbpx4
[8] ebs-csi-node-l8rx5
[9] efs-csi-node-v6m4m
[10] efs-csi-node-vtf5r
[11] kube-proxy-7gbmn
[12] kube-proxy-8h4tk

参考

https://pizi.netlify.app/posts/kubernetes-client-go-example/#node%E3%81%AE%E5%8F%96%E5%BE%97

https://github.com/kubernetes/client-go