使用 Kubernetes go API 客户端库设置节点执行 drain 操作的代码示例

好的，请参考以下的代码示例：

package main

import (
	"context"
	"flag"
	"fmt"
	"log"
	"time"

	"k8s.io/client-go/kubernetes"
	"k8s.io/client-go/tools/clientcmd"
	"k8s.io/client-go/util/retry"
	"k8s.io/kubernetes/pkg/api/v1"
)

func main() {
	var kubeconfig string
	flag.StringVar(&kubeconfig, "kubeconfig", "", "Path to kubeconfig file")
	flag.Parse()

	// Loading kubeconfig file
	config, err := clientcmd.BuildConfigFromFlags("", kubeconfig)
	if err != nil {
		log.Fatalf("Error building kubeconfig: %s", err.Error())
	}

	// Creating kubernetes clientset
	clientset, err := kubernetes.NewForConfig(config)
	if err != nil {
		log.Fatalf("Error creating kubernetes client: %s", err.Error())
	}

	// Node name to be drained
	nodeName := "node-1"

	// Fetching node with name 'nodeName'
	node, err := clientset.CoreV1().Nodes().Get(context.Background(), nodeName, v1.GetOptions{})
	if err != nil {
		log.Fatalf("Error getting node '%s': %s", nodeName, err.Error())
	}

	// Setting 'unschedulable' field of node to 'true'
	node.Spec.Unschedulable = true

	// Applying changes to node
	err = retry.RetryOnConflict(retry.DefaultRetry, func() error {
		_, updateErr := clientset.CoreV1().Nodes().Update(context.Background(), node, v1.UpdateOptions{})
		return updateErr
	})
	if err != nil {
		log.Fatalf("Error updating node '%s': %s", nodeName, err.Error())
	}

	// Waiting for all pods scheduled on the node to terminate
	for {
		pods, err := clientset.CoreV1().Pods("").List(context.Background(), v1.ListOptions{})
		if err != nil {
			log.Fatalf("Error listing pods: %s", err.Error())
		}

		// Checking if all pods are terminated
		allTerminated := true
		for _, pod := range pods.Items {
			if pod.Spec.NodeName == nodeName {
				allTerminated = false
				break
			}
		}

		if allTerminated {
			break
		}

		time.Sleep(5 * time.Second)
	}

	// Setting 'unschedulable' field of node to 'false'
	node.Spec.Unschedulable = false

	// Applying changes to node
	err = retry.RetryOnConflict(retry.DefaultRetry, func() error {
		_, updateErr := clientset.CoreV1().Nodes().Update(context.Background(), node, v1.UpdateOptions{})
		return updateErr
	})
	if err != nil {
		log.Fatalf("Error updating node '%s': %s", nodeName, err.Error())
	}

	fmt.Printf("Node '%s' drained successfully\n", nodeName)
}

这个程序将节点 "node-1" 设为不可调度状态（即执行 drain 操作），等待所有调度在该节点上的 Pod 终止，然后将节点设为可调度状态。注意，需要使用 RetryOnConflict 函数来避免更新期间的冲突。