k8s源码学习-client-go创建job任务

原创

梅花香自苦寒来 2022-04-08 17:52:35 博主文章分类：GO、K8s ©著作权

文章标签 client-go创建job 文章分类 kubernetes 云计算

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在kube-system命名空间下创建job: test-job,job执行ls -l命令：

测试环境：Mac+minikube

package main

import (
  "flag"
  "golang.org/x/net/context"
  batchv1 "k8s.io/api/batch/v1"
  v1 "k8s.io/api/core/v1"
  metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
  "k8s.io/client-go/kubernetes"
  "k8s.io/client-go/tools/clientcmd"
  "log"
  "os"
  "path/filepath"
  "strings"
)

//定义连接k8s集群的函数
func connectToK8s() *kubernetes.Clientset  {
  home,exists := os.LookupEnv("HOME")
  if !exists {
    home = "/root"
  }

  configPath := filepath.Join(home,".kube","config")
  config,err := clientcmd.BuildConfigFromFlags("",configPath)
  if err != nil{
    log.Fatalln("failed to create K8s config")
  }
  clientset,err := kubernetes.NewForConfig(config)
  if err != nil{
    log.Fatalln("Failed to create K8s clientset")
  }

  return clientset
}

//定义k8s job模板
func launchK8sJob(clientset *kubernetes.Clientset,jobName *string,image *string,cmd *string){
  jobs := clientset.BatchV1().Jobs("kube-system")
  var backOffLimit int32 = 0

  jobSpec := &batchv1.Job{
    ObjectMeta: metav1.ObjectMeta{
      Name: *jobName,
      Namespace: "kube-system",
    },
    Spec: batchv1.JobSpec{
      Template: v1.PodTemplateSpec{
        Spec: v1.PodSpec{
          Containers: []v1.Container{
            {
              Name: *jobName,
              Image:  *image,
              Command: strings.Split(*cmd, " "),
            },
          },
          //https://kubernetes.io/zh/docs/concepts/workloads/pods/pod-lifecycle/#restart-policy
          //Pod 的 spec 中包含一个 restartPolicy 字段，其可能取值包括 Always、OnFailure 和 Never。默认值是 Always。
          //restartPolicy 适用于 Pod 中的所有容器。restartPolicy 仅针对同一节点上 kubelet 的容器重启动作。当 Pod 中的容器退出时，kubelet 会按指数回退 方式计算重启的延迟（10s、20s、40s、...），其最长延迟为 5 分钟。 一旦某容器执行了 10 分钟并且没有出现问题，kubelet 对该容器的重启回退计时器执行 重置操作。
          RestartPolicy: v1.RestartPolicyNever,
        },
      },
      //Specifies the number of retries before marking this job failed. Defaults to 6 +optional
      //指定标记此任务失败之前的重试次数为0次，创建失败就不再创建。默认值为6
      BackoffLimit: &backOffLimit,
    },
  }
  _,err := jobs.Create(context.TODO(),jobSpec,metav1.CreateOptions{})
  if err != nil{
    log.Fatalln("Failed to create K8s job")
  }

  //print job details
  log.Printf("Create K8s job successfully")
}

//定义主函数并使用flag包实现命令行的传参
func main(){
  jobName := flag.String("jobname","test-job","请输入job的名字")
  containerImage := flag.String("image","ubuntu:latest","请输入镜像名")
  entryCommand := flag.String("command","ls -l","请输入命令")
  flag.Parse()
  clientset := connectToK8s()
  launchK8sJob(clientset,jobName,containerImage,entryCommand)
}

使用默认参数执行：

✗ go run main.go
2022/04/08 17:42:05 Create K8s job successfully

➜  ~ kubectl get job -n kube-system
NAME       COMPLETIONS   DURATION   AGE
test-job   0/1           12s        12s

➜  ~ kubectl get pod -n kube-system | grep test-job
test-job-h6z6c                     0/1     Completed   0              8m53s

➜  ~ kubectl logs -f test-job-h6z6c -n kube-system
total 48
lrwxrwxrwx   1 root root    7 Apr  5 04:59 bin -> usr/bin
drwxr-xr-x   2 root root 4096 Apr 15  2020 boot
drwxr-xr-x   5 root root  360 Apr  8 09:45 dev
drwxr-xr-x   1 root root 4096 Apr  8 09:45 etc
drwxr-xr-x   2 root root 4096 Apr 15  2020 home
lrwxrwxrwx   1 root root    7 Apr  5 04:59 lib -> usr/lib
lrwxrwxrwx   1 root root    9 Apr  5 04:59 lib32 -> usr/lib32
lrwxrwxrwx   1 root root    9 Apr  5 04:59 lib64 -> usr/lib64
lrwxrwxrwx   1 root root   10 Apr  5 04:59 libx32 -> usr/libx32
drwxr-xr-x   2 root root 4096 Apr  5 04:59 media
drwxr-xr-x   2 root root 4096 Apr  5 04:59 mnt
drwxr-xr-x   2 root root 4096 Apr  5 04:59 opt
dr-xr-xr-x 265 root root    0 Apr  8 09:45 proc
drwx------   2 root root 4096 Apr  5 05:02 root
drwxr-xr-x   1 root root 4096 Apr  8 09:45 run
lrwxrwxrwx   1 root root    8 Apr  5 04:59 sbin -> usr/sbin
drwxr-xr-x   2 root root 4096 Apr  5 04:59 srv
dr-xr-xr-x  12 root root    0 Apr  8 09:42 sys
drwxrwxrwt   2 root root 4096 Apr  5 05:02 tmp
drwxr-xr-x  13 root root 4096 Apr  5 04:59 usr
drwxr-xr-x  11 root root 4096 Apr  5 05:02 var

指定参数创建job

➜  client-go-create-job-command git:(master) ✗ go run main.go -command "ls -l home" -jobname "create-job-test"
2022/04/08 19:58:59 Create K8s job successfully

➜  ~ kubectl get job -n kube-system
NAME              COMPLETIONS   DURATION   AGE
create-job-test   1/1           8s         2m50s

➜  ~ kubectl get pod -n kube-system
NAME                               READY   STATUS      RESTARTS      AGE
coredns-64897985d-jq6tk            1/1     Running     1 (30d ago)   30d
create-job-test-lrm7z              0/1     Completed   0             12s

➜  ~ kubectl logs -f create-job-test-lrm7z -n kube-system
total 0