使用client-go工具调用kubernetes API接口的教程详解(v1.17版本)
来源：脚本之家
时间：2022-12-31 15:56:09 252浏览 收藏
IT行业相对于一般传统行业，发展更新速度更快，一旦停止了学习，很快就会被行业所淘汰。所以我们需要踏踏实实的不断学习，精进自己的技术，尤其是初学者。今天golang学习网给大家整理了《使用client-go工具调用kubernetes API接口的教程详解(v1.17版本)》，聊聊API、client-gokubernetes，我们一起来看看吧！
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 main
import (
"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 main
import (
"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 main
import (
"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 main
import (
"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 main
import (
"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 main
import (
"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.
今天带大家了解了API、client-gokubernetes的相关知识，希望对你有所帮助；关于Golang的技术知识我们会一点点深入介绍，欢迎大家关注golang学习网公众号，一起学习编程~
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