client-go实战之二:RESTClient

go mod init restclientdemo

go get k8s.io/api@v0.20.0
go get k8s.io/client-go@v0.20.0

package main

import (
	"context"
	"flag"
	"fmt"
	"k8s.io/client-go/kubernetes/scheme"
	"k8s.io/client-go/rest"
	"k8s.io/client-go/tools/clientcmd"
	"k8s.io/client-go/util/homedir"
	corev1 "k8s.io/api/core/v1"
	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
	"path/filepath"
)

func main() {
	var kubeconfig *string

	// home是家目录，如果能取得家目录的值，就可以用来做默认值
	if home:=homedir.HomeDir(); home != "" {
		// 如果输入了kubeconfig参数，该参数的值就是kubeconfig文件的绝对路径，
		// 如果没有输入kubeconfig参数，就用默认路径~/.kube/config
		kubeconfig = flag.String("kubeconfig", filepath.Join(home, ".kube", "config"), "(optional) absolute path to the kubeconfig file")
	} else {
		// 如果取不到当前用户的家目录，就没办法设置kubeconfig的默认目录了，只能从入参中取
		kubeconfig = flag.String("kubeconfig", "", "absolute path to the kubeconfig file")
	}

	flag.Parse()

	// 从本机加载kubeconfig配置文件，因此第一个参数为空字符串
	config, err := clientcmd.BuildConfigFromFlags("", *kubeconfig)

	// kubeconfig加载失败就直接退出了
	if err != nil {
		panic(err.Error())
	}

	// 参考path : /api/v1/namespaces/{namespace}/pods
	config.APIPath = "api"
	// pod的group是空字符串
	config.GroupVersion = &corev1.SchemeGroupVersion
	// 指定序列化工具
	config.NegotiatedSerializer = scheme.Codecs

	// 根据配置信息构建restClient实例
	restClient, err := rest.RESTClientFor(config)

	if err!=nil {
		panic(err.Error())
	}

	// 保存pod结果的数据结构实例
	result := &corev1.PodList{}

	//  指定namespace
	namespace := "kube-system"
	// 设置请求参数，然后发起请求
	// GET请求
	err = restClient.Get().
		//  指定namespace，参考path : /api/v1/namespaces/{namespace}/pods
		Namespace(namespace).
		// 查找多个pod，参考path : /api/v1/namespaces/{namespace}/pods
		Resource("pods").
		// 指定大小限制和序列化工具
		VersionedParams(&metav1.ListOptions{Limit:100}, scheme.ParameterCodec).
		// 请求
		Do(context.TODO()).
		// 结果存入result
		Into(result)

	if err != nil {
		panic(err.Error())
	}

	// 表头
	fmt.Printf("namespace\t status\t\t name\n")

	// 每个pod都打印namespace、status.Phase、name三个字段
	for _, d := range result.Items {
		fmt.Printf("%v\t %v\t %v\n",
			d.Namespace,
			d.Status.Phase,
			d.Name)
	}
}

(base) zhaoqindeMBP:restclientdemo zhaoqin$ go run main.go
namespace	 status		 name
kube-system	 Running	 coredns-7f89b7bc75-5pdwc
kube-system	 Running	 coredns-7f89b7bc75-nvbvm
kube-system	 Running	 etcd-hedy
kube-system	 Running	 kube-apiserver-hedy
kube-system	 Running	 kube-controller-manager-hedy
kube-system	 Running	 kube-flannel-ds-v84vc
kube-system	 Running	 kube-proxy-hlppx
kube-system	 Running	 kube-scheduler-hedy