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

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 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.

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