# client-go示例 访问kubernetes集群有几下几种方式： | 方式 | 特点 | 支持者 | | ---------------------------------------------------------------------- | ----------------------------------------------------- | ------ | | Kubernetes dashboard | 直接通过Web UI进行操作，简单直接，可定制化程度低 | 官方支持 | | kubectl | 命令行操作，功能最全，但是比较复杂，适合对其进行进一步的分装，定制功能，版本适配最好 | 官方支持 | | [client-go](https://github.com/kubernetes/client-go) | 从kubernetes的代码中抽离出来的客户端包，简单易用，但需要小心区分kubernetes的API版本 | 官方支持 | | [client-python](https://github.com/kubernetes-incubator/client-python) | python客户端，kubernetes-incubator | 官方支持 | | [Java client](https://github.com/fabric8io/kubernetes-client) | fabric8中的一部分，kubernetes的java客户端 | redhat | 下面，我们基于[client-go](https://github.com/kubernetes/client-go)，对Deployment升级镜像的步骤进行了定制，通过命令行传递一个Deployment的名字、应用容器名和新image名字的方式来升级。 ## kubernetes-client-go-sample 代码如下： ```go package main import ( "flag" "fmt" "os" "path/filepath" "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" ) func main() { var kubeconfig *string if home := homeDir(); home != "" { kubeconfig = flag.String("kubeconfig", filepath.Join(home, ".kube", "config"), "(optional) absolute path to the kubeconfig file") } else { kubeconfig = flag.String("kubeconfig", "", "absolute path to the kubeconfig file") } deploymentName := flag.String("deployment", "", "deployment name") imageName := flag.String("image", "", "new image name") appName := flag.String("app", "app", "application name") flag.Parse() if *deploymentName == "" { fmt.Println("You must specify the deployment name.") os.Exit(0) } if *imageName == "" { fmt.Println("You must specify the new image name.") os.Exit(0) } // use the current context in kubeconfig config, err := clientcmd.BuildConfigFromFlags("", *kubeconfig) if err != nil { panic(err.Error()) } // create the clientset clientset, err := kubernetes.NewForConfig(config) if err != nil { panic(err.Error()) } deployment, err := clientset.AppsV1beta1().Deployments("default").Get(*deploymentName, metav1.GetOptions{}) if err != nil { panic(err.Error()) } if errors.IsNotFound(err) { fmt.Printf("Deployment not found\n") } else if statusError, isStatus := err.(*errors.StatusError); isStatus { fmt.Printf("Error getting deployment%v\n", statusError.ErrStatus.Message) } else if err != nil { panic(err.Error()) } else { fmt.Printf("Found deployment\n") name := deployment.GetName() fmt.Println("name ->", name) containers := &deployment.Spec.Template.Spec.Containers found := false for i := range *containers { c := *containers if c[i].Name == *appName { found = true fmt.Println("Old image ->", c[i].Image) fmt.Println("New image ->", *imageName) c[i].Image = *imageName } } if found == false { fmt.Println("The application container not exist in the deployment pods.") os.Exit(0) } _, err := clientset.AppsV1beta1().Deployments("default").Update(deployment) if err != nil { panic(err.Error()) } } } func homeDir() string { if h := os.Getenv("HOME"); h != "" { return h } return os.Getenv("USERPROFILE") // windows } ``` 我们使用`kubeconfig`文件认证连接kubernetes集群，该文件默认的位置是`$HOME/.kube/config`。 该代码编译后可以直接在kubernetes集群之外，任何一个可以连接到API server的机器上运行。 **编译运行** ```bash $ go get github.com/rootsongjc/kubernetes-client-go-sample $ cd $GOPATH/src/github.com/rootsongjc/kubernetes-client-go-sample $ make $ ./update-deployment-image -h Usage of ./update-deployment-image: -alsologtostderr log to standard error as well as files -app string application name (default "app") -deployment string deployment name -image string new image name -kubeconfig string (optional) absolute path to the kubeconfig file (default "/Users/jimmy/.kube/config") -log_backtrace_at value when logging hits line file:N, emit a stack trace -log_dir string If non-empty, write log files in this directory -logtostderr log to standard error instead of files -stderrthreshold value logs at or above this threshold go to stderr -v value log level for V logs -vmodule value comma-separated list of pattern=N settings for file-filtered logging ``` **使用不存在的image更新** ```bash $ ./update-deployment-image -deployment filebeat-test -image harbor-001.jimmysong.io/library/analytics-docker-test:Build_9 Found deployment name -> filebeat-test Old image -> harbor-001.jimmysong.io/library/analytics-docker-test:Build_8 New image -> harbor-001.jimmysong.io/library/analytics-docker-test:Build_9 ``` 查看Deployment的event。 ```bash $ kubectl describe deployment filebeat-test Name: filebeat-test Namespace: default CreationTimestamp: Fri, 19 May 2017 15:12:28 +0800 Labels: k8s-app=filebeat-test Selector: k8s-app=filebeat-test Replicas: 2 updated | 3 total | 2 available | 2 unavailable StrategyType: RollingUpdate MinReadySeconds: 0 RollingUpdateStrategy: 1 max unavailable, 1 max surge Conditions: Type Status Reason ---- ------ ------ Available True MinimumReplicasAvailable Progressing True ReplicaSetUpdated OldReplicaSets: filebeat-test-2365467882 (2/2 replicas created) NewReplicaSet: filebeat-test-2470325483 (2/2 replicas created) Events: FirstSeen LastSeen Count From SubObjectPath Type ReasoMessage --------- -------- ----- ---- ------------- -------- ------------ 2h 1m 3 {deployment-controller } Normal ScalingReplicaSet Scaled down replica set filebeat-test-2365467882 to 2 1m 1m 1 {deployment-controller } Normal ScalingReplicaSet Scaled up replica set filebeat-test-2470325483 to 1 1m 1m 1 {deployment-controller } Normal ScalingReplicaSet Scaled up replica set filebeat-test-2470325483 to 2 ``` 可以看到老的ReplicaSet从3个replica减少到了2个，有2个使用新配置的replica不可用，目前可用的replica是2个。 这是因为我们指定的镜像不存在，查看Deployment的pod的状态。 ```bash $ kubectl get pods -l k8s-app=filebeat-test NAME READY STATUS RESTARTS AGE filebeat-test-2365467882-4zwx8 2/2 Running 0 33d filebeat-test-2365467882-rqskl 2/2 Running 0 33d filebeat-test-2470325483-6vjbw 1/2 ImagePullBackOff 0 4m filebeat-test-2470325483-gc14k 1/2 ImagePullBackOff 0 4m ``` 我们可以看到有两个pod正在拉取image。 **还原为原先的镜像** 将image设置为原来的镜像。 ```bash $ ./update-deployment-image -deployment filebeat-test -image harbor-001.jimmysong.io/library/analytics-docker-test:Build_8 Found deployment name -> filebeat-test Old image -> harbor-001.jimmysong.io/library/analytics-docker-test:Build_9 New image -> harbor-001.jimmysong.io/library/analytics-docker-test:Build_8 ``` 现在再查看Deployment的状态。 ```bash $ kubectl describe deployment filebeat-test Name: filebeat-test Namespace: default CreationTimestamp: Fri, 19 May 2017 15:12:28 +0800 Labels: k8s-app=filebeat-test Selector: k8s-app=filebeat-test Replicas: 3 updated | 3 total | 3 available | 0 unavailable StrategyType: RollingUpdate MinReadySeconds: 0 RollingUpdateStrategy: 1 max unavailable, 1 max surge Conditions: Type Status Reason ---- ------ ------ Available True MinimumReplicasAvailable Progressing True NewReplicaSetAvailable OldReplicaSets: NewReplicaSet: filebeat-test-2365467882 (3/3 replicas created) Events: FirstSeen LastSeen Count From SubObjectPath Type ReasoMessage --------- -------- ----- ---- ------------- -------- ------------ 2h 8m 3 {deployment-controller } Normal ScalingReplicaSet Scaled down replica set filebeat-test-2365467882 to 2 8m 8m 1 {deployment-controller } Normal ScalingReplicaSet Scaled up replica set filebeat-test-2470325483 to 1 8m 8m 1 {deployment-controller } Normal ScalingReplicaSet Scaled up replica set filebeat-test-2470325483 to 2 2h 1m 3 {deployment-controller } Normal ScalingReplicaSet Scaled up replica set filebeat-test-2365467882 to 3 1m 1m 1 {deployment-controller } Normal ScalingReplicaSet Scaled down replica set filebeat-test-2470325483 to 0 ``` 可以看到available的replica个数恢复成3了。 其实在使用该命令的过程中，通过kubernetes dashboard的页面上查看Deployment的状态更直观，更加方便故障排查。 ![使用kubernetes dashboard进行故障排查](/files/-LxznIPL2rf6YDUD44dh) 这也是dashboard最大的优势，简单、直接、高效。 --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://hezhiqiang.gitbook.io/kubernetes-handbook/kai-fa-zhi-nan/client-go-sample.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.