使用client?go工具调用kubernetes(API接口的教程详解(v1.17版本))

使用client?go工具调用kubernetes,API接口的教程详解(v1.17版本)，久久派带你了解更多相关信息。

目录

• 说明
• 效果
• 实现
• 1、拉取工具源码
• 2、创建目录结构
• 查询代码实例
• 创建deployment资源
• 更新deployment类型服务
• 删除deployment类型服务

说明

可以调取k8s API 接口的工具有很多，这里我就介绍下client-go

gitlab上client-go项目地址: https://github.com/kubernetes/client-go

这个工具是由kubernetes官方指定维护的，大家可以放心使用

效果

运行完成后，可以直接获取k8s集群信息等

实现

1、拉取工具源码

注意事项：https://github.com/kubernetes/client-go/blob/master/INSTALL.md

总结：一定要拉取跟集群对应版本的工具源码，比如我这里集群是1.17版本，那我就拉取17版本

go get k8s.io/client-go@v0.17.0

我是1.17版本的集群，所有依赖文件放在这了，可以直接使用client-go k8s1.17 api

2、创建目录结构

集群的角色配置文件（默认在/root/.kube/config）
kube/config

查询代码实例

查询pod信息

查看ferry命名空间下pod的信息，pod名字、pod的IP

vim kube-api.go

package mainimport (	\"fmt\"	metav1 \"k8s.io/apimachinery/pkg/apis/meta/v1\"	\"k8s.io/client-go/kubernetes\"	\"k8s.io/client-go/tools/clientcmd\")func main() {	config, err := clientcmd.BuildConfigFromFlags(\"\", \"kube/config\")	if err != nil {		panic(err)	}	client, _ := kubernetes.NewForConfig(config)	pods ,err := client.CoreV1().Pods(\"ferry\").List(metav1.ListOptions{})	if err != nil {		fmt.Println(err)		return	}	for _,v := range  pods.Items {		fmt.Printf(\" 命名空间是：%v\\n pod名字：%v\\n IP：%v\\n\\n\",v.Namespace,v.Name,v.Status.PodIP)	}}

自动关联依赖

go mod tidy

运行结果

$ go run kube-api.go

命名空间是：ferry
pod名字：ferry-backend-7949596679-h8lxb
IP：10.42.1.14

命名空间是：ferry
pod名字：ferry-mysql-8db8d49f7-6psbv
IP：10.42.1.11

查询一个pod是否在一个命名空间下

https://github.com/kubernetes/client-go/blob/master/examples/in-cluster-client-configuration/main.go
每3秒检查下nginx-74959fc858-cp48w是否在default命名空间下

package mainimport (	\"context\"	\"fmt\"	\"k8s.io/apimachinery/pkg/api/errors\"	metav1 \"k8s.io/apimachinery/pkg/apis/meta/v1\"	\"k8s.io/client-go/kubernetes\"	\"k8s.io/client-go/tools/clientcmd\"	\"time\")func main() {	config, err := clientcmd.BuildConfigFromFlags(\"\", \"kube/config\")	if err != nil {		panic(err)	}	clientset, err := kubernetes.NewForConfig(config)	if err != nil {		panic(err.Error())	}	for {		// get pods in all the namespaces by omitting namespace		// Or specify namespace to get pods in particular namespace		pods, err := clientset.CoreV1().Pods(\"\").List(context.TODO(), metav1.ListOptions{})		if err != nil {			panic(err.Error())		}		fmt.Printf(\"There are %d pods in the cluster\\n\", len(pods.Items))		// Examples for error handling:		// - Use helper functions e.g. errors.IsNotFound()		// - And/or cast to StatusError and use its properties like e.g. ErrStatus.Message		_, err = clientset.CoreV1().Pods(\"default\").Get(context.TODO(), \"nginx-74959fc858-cp48w\", metav1.GetOptions{})		if errors.IsNotFound(err) {			fmt.Printf(\"Pod nginx-74959fc858-cp48w not found in default namespace\\n\")		} else if statusError, isStatus := err.(*errors.StatusError); isStatus {			fmt.Printf(\"Error getting pod %v\\n\", statusError.ErrStatus.Message)		} else if err != nil {			panic(err.Error())		} else {			fmt.Printf(\"Found nginx-74959fc858-cp48w pod in default namespace\\n\")		}	 time.Sleep(3 * time.Second)	}}

运行结果

$ go run kube-api.go
There are 22 pods in the cluster
Found nginx-74959fc858-cp48w pod in default namespace
There are 22 pods in the cluster
Found nginx-74959fc858-cp48w pod in default namespace
There are 22 pods in the cluster
Found nginx-74959fc858-cp48w pod in default namespace
There are 23 pods in the cluster
Found nginx-74959fc858-cp48w pod in default namespace
There are 22 pods in the cluster
Found nginx-74959fc858-cp48w pod in default namespace
There are 22 pods in the cluster
Found nginx-74959fc858-cp48w pod in default namespace
There are 21 pods in the cluster
\\\\在集群种手动删除了这个pod
Pod nginx-74959fc858-cp48w not found in default namespace
There are 21 pods in the cluster
Pod nginx-74959fc858-cp48w not found in default namespace

查询deployment服务类型信息

查询default命名空间下的deployment服务信息，服务名字、服务副本数

package mainimport (	\"fmt\"	metav1 \"k8s.io/apimachinery/pkg/apis/meta/v1\"	\"k8s.io/client-go/kubernetes\"	\"k8s.io/client-go/tools/clientcmd\")func main() {	config, err := clientcmd.BuildConfigFromFlags(\"\", \"kube/config\")	if err != nil {		panic(err)	}	client, _ := kubernetes.NewForConfig(config)	deploymentList, err := client.AppsV1().Deployments(\"default\").List(metav1.ListOptions{})	if err != nil {		fmt.Println(err)		return	}	for _,v := range deploymentList.Items {		fmt.Printf(\" 命名空间是：%v\\n deployment服务名字：%v\\n 副本个数：%v\\n\\n\",v.Namespace,v.Name,v.Status.Replicas)	}}

运行结果

$ go run kube-api.go
命名空间是：default
deployment服务名字：nginx
副本个数：2

创建deployment资源

https://github.com/kubernetes/client-go/blob/master/examples/create-update-delete-deployment/main.go

复制一个config文件到当前目录下

创建一个deployment类型的nginx服务

vim deployment-create.go

package mainimport (	\"context\"	\"flag\"	\"fmt\"	\"path/filepath\"	appsv1 \"k8s.io/api/apps/v1\"	apiv1 \"k8s.io/api/core/v1\"	metav1 \"k8s.io/apimachinery/pkg/apis/meta/v1\"	\"k8s.io/client-go/kubernetes\"	\"k8s.io/client-go/tools/clientcmd\"	\"k8s.io/client-go/util/homedir\"	//	// Uncomment to load all auth plugins	// _ \"k8s.io/client-go/plugin/pkg/client/auth\"	//	// Or uncomment to load specific auth plugins	// _ \"k8s.io/client-go/plugin/pkg/client/auth/azure\"	// _ \"k8s.io/client-go/plugin/pkg/client/auth/gcp\"	// _ \"k8s.io/client-go/plugin/pkg/client/auth/oidc\"	// _ \"k8s.io/client-go/plugin/pkg/client/auth/openstack\")func main() {	var kubeconfig *string	if home := homedir.HomeDir(); home != \"\" {		kubeconfig = flag.String(\"kubeconfig\", filepath.Join(\"config\"), \"(optional) absolute path to the kubeconfig file\")	} else {		kubeconfig = flag.String(\"kubeconfig\", \"\", \"absolute path to the kubeconfig file\")	}	flag.Parse()	config, err := clientcmd.BuildConfigFromFlags(\"\", *kubeconfig)	if err != nil {		panic(err)	}	clientset, err := kubernetes.NewForConfig(config)	if err != nil {		panic(err)	}	deploymentsClient := clientset.AppsV1().Deployments(apiv1.NamespaceDefault)	deployment := &appsv1.Deployment{		ObjectMeta: metav1.ObjectMeta{			Name: \"nginx-deployment\",		},		Spec: appsv1.DeploymentSpec{			Replicas: int32Ptr(2),			Selector: &metav1.LabelSelector{				MatchLabels: map[string]string{					\"app\": \"nginx\",				},			},			Template: apiv1.PodTemplateSpec{				ObjectMeta: metav1.ObjectMeta{					Labels: map[string]string{						\"app\": \"nginx\",					},				},				Spec: apiv1.PodSpec{					Containers: []apiv1.Container{						{							Name:  \"web\",							Image: \"nginx:1.12\",							Ports: []apiv1.ContainerPort{								{									Name:          \"http\",									Protocol:      apiv1.ProtocolTCP,									ContainerPort: 80,								},							},						},					},				},			},		},	}	// Create Deployment	fmt.Println(\"Creating deployment nginx...\")	result, err := deploymentsClient.Create(context.TODO(), deployment, metav1.CreateOptions{})	if err != nil {		panic(err)	}	fmt.Printf(\"Created deployment %q.\\n\", result.GetObjectMeta().GetName())}

运行结果

$ go run deployment-create.go
Creating deployment nginx…
Created deployment \”nginx-deployment\”.

更新deployment类型服务

https://github.com/kubernetes/client-go/blob/master/examples/create-update-delete-deployment/main.go
更改服务的副本数，由上一步创建的2修改成1，并修改镜像由nginx1.12–>nginx1.13

package mainimport (	\"context\"	\"flag\"	\"fmt\"	\"path/filepath\"	apiv1 \"k8s.io/api/core/v1\"	metav1 \"k8s.io/apimachinery/pkg/apis/meta/v1\"	\"k8s.io/client-go/kubernetes\"	\"k8s.io/client-go/tools/clientcmd\"	\"k8s.io/client-go/util/homedir\"	\"k8s.io/client-go/util/retry\"	//	// Uncomment to load all auth plugins	// _ \"k8s.io/client-go/plugin/pkg/client/auth\"	//	// Or uncomment to load specific auth plugins	// _ \"k8s.io/client-go/plugin/pkg/client/auth/azure\"	// _ \"k8s.io/client-go/plugin/pkg/client/auth/gcp\"	// _ \"k8s.io/client-go/plugin/pkg/client/auth/oidc\"	// _ \"k8s.io/client-go/plugin/pkg/client/auth/openstack\")func main() {	var kubeconfig *string	if home := homedir.HomeDir(); home != \"\" {		kubeconfig = flag.String(\"kubeconfig\", filepath.Join(\"config\"), \"(optional) absolute path to the kubeconfig file\")	} else {		kubeconfig = flag.String(\"kubeconfig\", \"\", \"absolute path to the kubeconfig file\")	}	flag.Parse()	config, err := clientcmd.BuildConfigFromFlags(\"\", *kubeconfig)	if err != nil {		panic(err)	}	clientset, err := kubernetes.NewForConfig(config)	if err != nil {		panic(err)	}	deploymentsClient := clientset.AppsV1().Deployments(apiv1.NamespaceDefault)	retryErr := retry.RetryOnConflict(retry.DefaultRetry, func() error {		// Retrieve the latest version of Deployment before attempting update		// RetryOnConflict uses exponential backoff to avoid exhausting the apiserver		result, getErr := deploymentsClient.Get(context.TODO(), \"nginx-deployment\", metav1.GetOptions{})		if getErr != nil {			panic(fmt.Errorf(\"Failed to get latest version of Deployment: %v\", getErr))		}		result.Spec.Replicas = int32Ptr(1)                           // reduce replica count		result.Spec.Template.Spec.Containers[0].Image = \"nginx:1.13\" // change nginx version		_, updateErr := deploymentsClient.Update(context.TODO(), result, metav1.UpdateOptions{})		return updateErr	})	if retryErr != nil {		panic(fmt.Errorf(\"Update failed: %v\", retryErr))	}	fmt.Println(\"Updated deployment nginx\")}func int32Ptr(i int32) *int32 { return &i }

运行结果

$ go run deployment-update.go
Updated deployment nginx

删除deployment类型服务

删除上面创建的nginx-deployment资源，删除之前添加了确认语句

package mainimport (	\"bufio\"	\"context\"	\"flag\"	\"fmt\"	\"os\"	\"path/filepath\"	apiv1 \"k8s.io/api/core/v1\"	metav1 \"k8s.io/apimachinery/pkg/apis/meta/v1\"	\"k8s.io/client-go/kubernetes\"	\"k8s.io/client-go/tools/clientcmd\"	\"k8s.io/client-go/util/homedir\"	//	// Uncomment to load all auth plugins	// _ \"k8s.io/client-go/plugin/pkg/client/auth\"	//	// Or uncomment to load specific auth plugins	// _ \"k8s.io/client-go/plugin/pkg/client/auth/azure\"	// _ \"k8s.io/client-go/plugin/pkg/client/auth/gcp\"	// _ \"k8s.io/client-go/plugin/pkg/client/auth/oidc\"	// _ \"k8s.io/client-go/plugin/pkg/client/auth/openstack\")func main() {	var kubeconfig *string	if home := homedir.HomeDir(); home != \"\" {		kubeconfig = flag.String(\"kubeconfig\", filepath.Join( \"config\"), \"(optional) absolute path to the kubeconfig file\")	} else {		kubeconfig = flag.String(\"kubeconfig\", \"\", \"absolute path to the kubeconfig file\")	}	flag.Parse()	config, err := clientcmd.BuildConfigFromFlags(\"\", *kubeconfig)	if err != nil {		panic(err)	}	clientset, err := kubernetes.NewForConfig(config)	if err != nil {		panic(err)	}	deploymentsClient := clientset.AppsV1().Deployments(apiv1.NamespaceDefault)     prompt()	fmt.Println(\"Deleting deployment nginx...\")	deletePolicy := metav1.DeletePropagationForeground	if err := deploymentsClient.Delete(context.TODO(), \"nginx-deployment\", metav1.DeleteOptions{		PropagationPolicy: &deletePolicy,	}); err != nil {		panic(err)	}	fmt.Println(\"Deleted deployment.\")}func prompt() {	fmt.Printf(\"-> Press Return key to continue, will delete!\")	scanner := bufio.NewScanner(os.Stdin)	for scanner.Scan() {		break	}	if err := scanner.Err(); err != nil {		panic(err)	}	fmt.Println()}func int32Ptr(i int32) *int32 { return &i }

运行结果

$ go run deployment-delete.go
-> Press Return key to continue, will delete! 这里点击回车后继续删除资源

Deleting deployment nginx…
Deleted deployment.

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