• client-go示例
    • kubernetes-client-go-sample

    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 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 python客户端,kubernetes-incubator 官方支持
    Java client fabric8中的一部分,kubernetes的java客户端 redhat

    下面,我们基于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。代码和使用方式见 https://github.com/rootsongjc/kubernetes-client-go-sample 。

    kubernetes-client-go-sample

    代码如下:

    1. package main
    2. import (
    3. "flag"
    4. "fmt"
    5. "os"
    6. "path/filepath"
    7. "k8s.io/apimachinery/pkg/api/errors"
    8. metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
    9. "k8s.io/client-go/kubernetes"
    10. "k8s.io/client-go/tools/clientcmd"
    11. )
    12. func main() {
    13. var kubeconfig *string
    14. if home := homeDir(); home != "" {
    15. kubeconfig = flag.String("kubeconfig", filepath.Join(home, ".kube", "config"), "(optional) absolute path to the kubeconfig file")
    16. } else {
    17. kubeconfig = flag.String("kubeconfig", "", "absolute path to the kubeconfig file")
    18. }
    19. deploymentName := flag.String("deployment", "", "deployment name")
    20. imageName := flag.String("image", "", "new image name")
    21. appName := flag.String("app", "app", "application name")
    22. flag.Parse()
    23. if *deploymentName == "" {
    24. fmt.Println("You must specify the deployment name.")
    25. os.Exit(0)
    26. }
    27. if *imageName == "" {
    28. fmt.Println("You must specify the new image name.")
    29. os.Exit(0)
    30. }
    31. // use the current context in kubeconfig
    32. config, err := clientcmd.BuildConfigFromFlags("", *kubeconfig)
    33. if err != nil {
    34. panic(err.Error())
    35. }
    36. // create the clientset
    37. clientset, err := kubernetes.NewForConfig(config)
    38. if err != nil {
    39. panic(err.Error())
    40. }
    41. deployment, err := clientset.AppsV1beta1().Deployments("default").Get(*deploymentName, metav1.GetOptions{})
    42. if err != nil {
    43. panic(err.Error())
    44. }
    45. if errors.IsNotFound(err) {
    46. fmt.Printf("Deployment not found\n")
    47. } else if statusError, isStatus := err.(*errors.StatusError); isStatus {
    48. fmt.Printf("Error getting deployment%v\n", statusError.ErrStatus.Message)
    49. } else if err != nil {
    50. panic(err.Error())
    51. } else {
    52. fmt.Printf("Found deployment\n")
    53. name := deployment.GetName()
    54. fmt.Println("name ->", name)
    55. containers := &deployment.Spec.Template.Spec.Containers
    56. found := false
    57. for i := range *containers {
    58. c := *containers
    59. if c[i].Name == *appName {
    60. found = true
    61. fmt.Println("Old image ->", c[i].Image)
    62. fmt.Println("New image ->", *imageName)
    63. c[i].Image = *imageName
    64. }
    65. }
    66. if found == false {
    67. fmt.Println("The application container not exist in the deployment pods.")
    68. os.Exit(0)
    69. }
    70. _, err := clientset.AppsV1beta1().Deployments("default").Update(deployment)
    71. if err != nil {
    72. panic(err.Error())
    73. }
    74. }
    75. }
    76. func homeDir() string {
    77. if h := os.Getenv("HOME"); h != "" {
    78. return h
    79. }
    80. return os.Getenv("USERPROFILE") // windows
    81. }

    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

    1. $ go get github.com/rootsongjc/kubernetes-client-go-sample
    2. $ cd $GOPATH/src/github.com/rootsongjc/kubernetes-client-go-sample
    3. $ make
    4. $ ./update-deployment-image -h
    5. Usage of ./update-deployment-image:
    6. -alsologtostderr
    7. log to standard error as well as files
    8. -app string
    9. application name (default "app")
    10. -deployment string
    11. deployment name
    12. -image string
    13. new image name
    14. -kubeconfig string
    15. (optional) absolute path to the kubeconfig file (default "/Users/jimmy/.kube/config")
    16. -log_backtrace_at value
    17. when logging hits line file:N, emit a stack trace
    18. -log_dir string
    19. If non-empty, write log files in this directory
    20. -logtostderr
    21. log to standard error instead of files
    22. -stderrthreshold value
    23. logs at or above this threshold go to stderr
    24. -v value
    25. log level for V logs
    26. -vmodule value
    27. comma-separated list of pattern=N settings for file-filtered logging

    使用不存在的image更新

    1. $ ./update-deployment-image -deployment filebeat-test -image sz-pg-oam-docker-hub-001.tendcloud.com/library/analytics-docker-test:Build_9
    2. Found deployment
    3. name -> filebeat-test
    4. Old image -> sz-pg-oam-docker-hub-001.tendcloud.com/library/analytics-docker-test:Build_8
    5. New image -> sz-pg-oam-docker-hub-001.tendcloud.com/library/analytics-docker-test:Build_9

    查看Deployment的event。

    1. $ kubectl describe deployment filebeat-test
    2. Name: filebeat-test
    3. Namespace: default
    4. CreationTimestamp: Fri, 19 May 2017 15:12:28 +0800
    5. Labels: k8s-app=filebeat-test
    6. Selector: k8s-app=filebeat-test
    7. Replicas: 2 updated | 3 total | 2 available | 2 unavailable
    8. StrategyType: RollingUpdate
    9. MinReadySeconds: 0
    10. RollingUpdateStrategy: 1 max unavailable, 1 max surge
    11. Conditions:
    12. Type Status Reason
    13. ---- ------ ------
    14. Available True MinimumReplicasAvailable
    15. Progressing True ReplicaSetUpdated
    16. OldReplicaSets: filebeat-test-2365467882 (2/2 replicas created)
    17. NewReplicaSet: filebeat-test-2470325483 (2/2 replicas created)
    18. Events:
    19. FirstSeen LastSeen Count From SubObjectPath Type ReasoMessage
    20. --------- -------- ----- ---- ------------- -------- ------------
    21. 2h 1m 3 {deployment-controller } Normal ScalingReplicaSet Scaled down replica set filebeat-test-2365467882 to 2
    22. 1m 1m 1 {deployment-controller } Normal ScalingReplicaSet Scaled up replica set filebeat-test-2470325483 to 1
    23. 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。

    1. $ kubectl get pods -l k8s-app=filebeat-test
    2. NAME READY STATUS RESTARTS AGE
    3. filebeat-test-2365467882-4zwx8 2/2 Running 0 33d
    4. filebeat-test-2365467882-rqskl 2/2 Running 0 33d
    5. filebeat-test-2470325483-6vjbw 1/2 ImagePullBackOff 0 4m
    6. 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。

    1. $ ./update-deployment-image -deployment filebeat-test -image sz-pg-oam-docker-hub-001.tendcloud.com/library/analytics-docker-test:Build_8
    2. Found deployment
    3. name -> filebeat-test
    4. Old image -> sz-pg-oam-docker-hub-001.tendcloud.com/library/analytics-docker-test:Build_9
    5. New image -> sz-pg-oam-docker-hub-001.tendcloud.com/library/analytics-docker-test:Build_8

    现在再查看Deployment的状态。

    1. $ kubectl describe deployment filebeat-test
    2. Name: filebeat-test
    3. Namespace: default
    4. CreationTimestamp: Fri, 19 May 2017 15:12:28 +0800
    5. Labels: k8s-app=filebeat-test
    6. Selector: k8s-app=filebeat-test
    7. Replicas: 3 updated | 3 total | 3 available | 0 unavailable
    8. StrategyType: RollingUpdate
    9. MinReadySeconds: 0
    10. RollingUpdateStrategy: 1 max unavailable, 1 max surge
    11. Conditions:
    12. Type Status Reason
    13. ---- ------ ------
    14. Available True MinimumReplicasAvailable
    15. Progressing True NewReplicaSetAvailable
    16. OldReplicaSets: <none>
    17. NewReplicaSet: filebeat-test-2365467882 (3/3 replicas created)
    18. Events:
    19. FirstSeen LastSeen Count From SubObjectPath Type ReasoMessage
    20. --------- -------- ----- ---- ------------- -------- ------------
    21. 2h 8m 3 {deployment-controller } Normal ScalingReplicaSet Scaled down replica set filebeat-test-2365467882 to 2
    22. 8m 8m 1 {deployment-controller } Normal ScalingReplicaSet Scaled up replica set filebeat-test-2470325483 to 1
    23. 8m 8m 1 {deployment-controller } Normal ScalingReplicaSet Scaled up replica set filebeat-test-2470325483 to 2
    24. 2h 1m 3 {deployment-controller } Normal ScalingReplicaSet Scaled up replica set filebeat-test-2365467882 to 3
    25. 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

    这也是dashboard最大的优势,简单、直接、高效。