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

main.go

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