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