K8S-Controller-(Job和Cronjob)-一次任务和定时任务

忘是亡心i 2022-12-27 08:27 212阅读 0赞

### K8S-Controller-Job和Cronjob-一次任务和定时任务 ###

*  Job - 一次性任务
 *   *  Job终止和清理
     *  特殊说明
     *  Job示例
 *  Cronjob - 定时任务
 *   *  CronJob 限制
     *  特殊说明
     *  CronJob示例

Controller-Job和Cronjob-一次性任务和定时任务

# Job - 一次性任务 #

负责批处理任务

Job创建一个或多个Pod，并确保指定数量的Pod成功终止。Pod成功完成后，Job将跟踪成功完成的情况。当达到指定的成功完成次数时，任务（即Job）就完成了。删除Job将清除其创建的Pod。

一个简单的情况是创建一个Job对象，以便可靠地运行一个Pod来完成。如果第一个Pod发生故障或被删除（例如，由于节点硬件故障或节点重启），则Job对象将启动一个新的Pod。

当然还可以使用Job并行运行多个Pod。

apiVersion: batch/v1
    kind: job
    metadata:
      ...............

# 创建一次性任务
    kubectl create -f job.yaml
    
    # 查看
    kubectl get pods
    #执行完成后，状态Status会变为Completed
    
    #删除任务
    kubectl delete -f job.yaml

## Job终止和清理 ##

Job完成后，不会再创建其他Pod，但是Pod也不会被删除。这样使我们仍然可以查看已完成容器的日志，以检查是否有错误、警告或其他诊断输出。Job对象在完成后也将保留下来，以便您查看其状态。

当我们删除Job对象时，对应的pod也会被删除。

## 特殊说明 ##

*  单个Pod时，默认Pod成功运行后Job即结束
 *  restartPolicy 仅支持Never和OnFailure
 *  .spec.completions 标识Job结束所需要成功运行的Pod个数，默认为1
 *  .spec.parallelism 标识并行运行的Pod个数，默认为1
 *  .spec.activeDeadlineSeconds 为Job的持续时间，不管有多少Pod创建。一旦工作到指定时间，所有的运行pod都会终止且工作状态将成为type: Failed与reason: DeadlineExceeded。

## Job示例 ##

yaml文件

[root@k8s-master controller]# pwd
    /root/k8s_practice/controller
    [root@k8s-master controller]# cat job.yaml
    apiVersion: batch/v1
    kind: Job
    metadata:
      name: pi
    spec:
      #completions: 3 # 标识Job结束所需要成功运行的Pod个数，默认为1
      template:
        spec:
          containers:
          - name: pi
            image: registry.cn-beijing.aliyuncs.com/google_registry/perl:5.26
            command: ["perl",  "-Mbignum=bpi", "-wle", "print bpi(2000)"]
          restartPolicy: Never
      backoffLimit: 4

创建job，与状态查看

[root@k8s-master controller]# kubectl apply -f job.yaml
    job.batch/pi created
    [root@k8s-master controller]# kubectl get job -o wide
    NAME   COMPLETIONS   DURATION   AGE   CONTAINERS   IMAGES                                                       SELECTOR
    pi     0/1           16s        16s   pi           registry.cn-beijing.aliyuncs.com/google_registry/perl:5.26   controller-uid=77004357-fd5e-4395-9bbb-cd0698e19cb9
    [root@k8s-master controller]# kubectl get pod -o wide
    NAME       READY   STATUS              RESTARTS   AGE   IP       NODE         NOMINATED NODE   READINESS GATES
    pi-6zvm5   0/1     ContainerCreating   0          85s   <none>   k8s-node01   <none>           <none>

之后再次查看

[root@k8s-master controller]# kubectl get job -o wide
    NAME   COMPLETIONS   DURATION   AGE   CONTAINERS   IMAGES                                                       SELECTOR
    pi     1/1           14m        44m   pi           registry.cn-beijing.aliyuncs.com/google_registry/perl:5.26   controller-uid=77004357-fd5e-4395-9bbb-cd0698e19cb9
    [root@k8s-master controller]# kubectl get pod -o wide
    NAME       READY   STATUS      RESTARTS   AGE   IP            NODE         NOMINATED NODE   READINESS GATES
    pi-6zvm5   0/1     Completed   0          44m   10.244.4.63   k8s-node01   <none>           <none>
    [root@k8s-master controller]#
    [root@k8s-master controller]# kubectl describe job pi
    Name:           pi
    Namespace:      default
    Selector:       controller-uid=76680f6f-442c-4a09-91dc-c3d4c18465b0
    Labels:         controller-uid=76680f6f-442c-4a09-91dc-c3d4c18465b0
                    job-name=pi
    Annotations:    kubectl.kubernetes.io/last-applied-configuration:
                      { "apiVersion":"batch/v1","kind":"Job","metadata":{ "annotations":{ },"name":"pi","namespace":"default"},"spec":{ "backoffLimit":4,"
    Parallelism:    1
    Completions:    1
    Start Time:     Tue, 11 Aug 2020 23:34:44 +0800
    Completed At:   Tue, 11 Aug 2020 23:35:02 +0800
    Duration:       18s
    Pods Statuses:  0 Running / 1 Succeeded / 0 Failed
    Pod Template:
      Labels:  controller-uid=76680f6f-442c-4a09-91dc-c3d4c18465b0
               job-name=pi
      Containers:
       pi:
        Image:      registry.cn-beijing.aliyuncs.com/google_registry/perl:5.26
        Port:       <none>
        Host Port:  <none>
        Command:
          perl
          -Mbignum=bpi
          -wle
          print bpi(2000)
        Environment:  <none>
        Mounts:       <none>
      Volumes:        <none>
    Events:
      Type    Reason            Age    From            Message
      ----    ------            ----   ----            -------
      Normal  SuccessfulCreate  2m33s  job-controller  Created pod: pi-6zvm5

并查看 Pod 的标准输出

[root@k8s-master controller]# kubectl logs --tail 500 pi-6zvm5
    3.141592653589793238462643383279502884197169399375105820974944592307816406………………

# Cronjob - 定时任务 #

Cron Job 创建是基于时间调度的 Jobs

一个 CronJob 对象就像 crontab (cron table) 文件中的一行。它用 Cron 格式进行编写，并周期性地在给定的调度时间执行 Job。

apiVersion: batch/v1beta1
    kind: CronJob
    metadata:
      name: hello
    spec:
      schedule: "*/1 * * * *"
    .................

#创建任务
    kubectl applf -y cronjob.yaml
    
    #查看
    kubectl get pods

## CronJob 限制 ##

CronJob 创建 Job 对象，每个 Job 的执行次数大约为一次。 之所以说 “大约” ，是因为在某些情况下，可能会创建两个 Job，或者不会创建任何 Job。虽然试图使这些情况尽量少发生，但不能完全杜绝。因此，Job 应该是幂等的。

CronJob 仅负责创建与其调度时间相匹配的 Job，而 Job 又负责管理其代表的 Pod。

**使用案例：**

1、在给定时间点调度Job

2、创建周期性运行的Job。如：数据备份、数仓导数、执行任务、邮件发送、数据拉取、数据推送

## 特殊说明 ##

.spec.schedule 必选，任务被创建和执行的调度时间。同Cron格式串，例如 0 \* \* \* \*。

*  .spec.jobTemplate 必选，任务模版。它和 Job的语法完全一样
 *  .spec.startingDeadlineSeconds 可选的。默认未设置。它表示任务如果由于某种原因错过了调度时间，开始该任务的截止时间的秒数。过了截止时间，CronJob 就不会开始任务。不满足这种最后期限的任务会被统计为失败任务。如果没有该声明，那任务就没有最后期限。
 *  .spec.concurrencyPolicy 可选的。它声明了 CronJob 创建的任务执行时发生重叠如何处理。spec 仅能声明下列规则中的一种：

Allow (默认)：CronJob 允许并发任务执行。
    Forbid：CronJob 不允许并发任务执行；如果新任务的执行时间到了而老任务没有执行完，CronJob 会忽略新任务的执行。
    Replace：如果新任务的执行时间到了而老任务没有执行完，CronJob 会用新任务替换当前正在运行的任务。

请注意，并发性规则仅适用于相同 CronJob 创建的任务。如果有多个 CronJob，它们相应的任务总是允许并发执行的。

*  .spec.suspend 可选的。如果设置为 true ，后续发生的执行都会挂起。这个设置对已经开始执行的Job不起作用。默认是关闭的false。  
    备注：在调度时间内挂起的执行都会被统计为错过的任务。当 .spec.suspend 从 true 改为 false 时，且没有开始的最后期限，错过的任务会被立即调度。
 *  .spec.successfulJobsHistoryLimit 和 .spec.failedJobsHistoryLimit 可选的。 这两个声明了有多少执行完成和失败的任务会被保留。默认设置为3和1。限制设置为0代表相应类型的任务完成后不会保留。

说明：如果 startingDeadlineSeconds 设置为很大的数值或未设置（默认），并且 concurrencyPolicy 设置为 Allow，则作业将始终至少运行一次。

## CronJob示例 ##

yaml文件

[root@k8s-master controller]# pwd
    /root/k8s_practice/controller
    [root@k8s-master controller]# cat cronjob.yaml
    apiVersion: batch/v1beta1
    kind: CronJob
    metadata:
      name: hello
    spec:
      schedule: "*/1 * * * *"
      jobTemplate:
        spec:
          template:
            spec:
              containers:
              - name: hello
                image: registry.cn-beijing.aliyuncs.com/google_registry/busybox:1.24
                args:
                - /bin/sh
                - -c
                - date; echo Hello from the Kubernetes cluster
              restartPolicy: OnFailure

启动cronjob并查看状态

[root@k8s-master controller]# kubectl apply -f cronjob.yaml
    cronjob.batch/hello created
    [root@k8s-master controller]# kubectl get cronjob -o wide
    NAME    SCHEDULE      SUSPEND   ACTIVE   LAST SCHEDULE   AGE   CONTAINERS   IMAGES                                                          SELECTOR
    hello   */1 * * * *   False     1        8s              27s   hello        registry.cn-beijing.aliyuncs.com/google_registry/busybox:1.24   <none>
    [root@k8s-master controller]#
    [root@k8s-master controller]# kubectl get job -o wide
    NAME               COMPLETIONS   DURATION   AGE   CONTAINERS   IMAGES                                                          SELECTOR
    hello-1590721020   1/1           2s         21s   hello        registry.cn-beijing.aliyuncs.com/google_registry/busybox:1.24   controller-uid=9e0180e8-8362-4a58-8b93-089b92774b5e
    [root@k8s-master controller]#
    [root@k8s-master controller]# kubectl get pod -o wide
    NAME                     READY   STATUS      RESTARTS   AGE   IP            NODE         NOMINATED NODE   READINESS GATES
    hello-1590721020-m4fr8   0/1     Completed   0          36s   10.244.4.66   k8s-node01   <none>           <none>

几分钟之后的状态信息

[root@k8s-master controller]# kubectl get cronjob -o wide
    NAME    SCHEDULE      SUSPEND   ACTIVE   LAST SCHEDULE   AGE     CONTAINERS   IMAGES                                                          SELECTOR
    hello   */1 * * * *   False     0        55s             7m14s   hello        registry.cn-beijing.aliyuncs.com/google_registry/busybox:1.24   <none>
    [root@k8s-master controller]#
    [root@k8s-master controller]#
    [root@k8s-master controller]# kubectl get job -o wide
    NAME               COMPLETIONS   DURATION   AGE    CONTAINERS   IMAGES                                                          SELECTOR
    hello-1590721260   1/1           1s         3m1s   hello        registry.cn-beijing.aliyuncs.com/google_registry/busybox:1.24   controller-uid=0676bd6d-861b-440b-945b-4b2704872728
    hello-1590721320   1/1           2s         2m1s   hello        registry.cn-beijing.aliyuncs.com/google_registry/busybox:1.24   controller-uid=09c1902e-76ef-4731-b3b4-3188961c13e9
    hello-1590721380   1/1           2s         61s    hello        registry.cn-beijing.aliyuncs.com/google_registry/busybox:1.24   controller-uid=f30dc159-8905-4cfc-b06b-f950c8dcfc28
    [root@k8s-master controller]#
    [root@k8s-master controller]# kubectl get pod -o wide
    NAME                     READY   STATUS      RESTARTS   AGE    IP            NODE         NOMINATED NODE   READINESS GATES
    hello-1590721320-m4pxf   0/1     Completed   0          2m6s   10.244.4.70   k8s-node01   <none>           <none>
    hello-1590721380-wk7jh   0/1     Completed   0          66s    10.244.2.77   k8s-node02   <none>           <none>
    hello-1590721440-rcx7v   0/1     Completed   0          6s     10.244.4.72   k8s-node01   <none>           <none>
    [root@k8s-master controller]#
    [root@k8s-master controller]# kubectl describe cronjob hello
    Name:                          hello
    Namespace:                     default
    Labels:                        <none>
    Annotations:                   kubectl.kubernetes.io/last-applied-configuration:
                                     { "apiVersion":"batch/v1beta1","kind":"CronJob","metadata":{ "annotations":{ },"name":"hello","namespace":"default"},"spec":{ "jobTemplate":{ "...
    Schedule:                      */1 * * * *
    Concurrency Policy:            Allow
    Suspend:                       False
    Successful Job History Limit:  3
    Failed Job History Limit:      1
    Starting Deadline Seconds:     <unset>
    Selector:                      <unset>
    Parallelism:                   <unset>
    Completions:                   <unset>
    Pod Template:
      Labels:  <none>
      Containers:
       hello:
        Image:      registry.cn-beijing.aliyuncs.com/google_registry/busybox:1.24
        Port:       <none>
        Host Port:  <none>
        Args:
          /bin/sh
          -c
          date; echo Hello from the Kubernetes cluster
        Environment:     <none>
        Mounts:          <none>
      Volumes:           <none>
    Last Schedule Time:  Wed, 12 Aug 2020 00:01:00 +0800
    Active Jobs:         <none>
    Events:
      Type    Reason            Age                  From                Message
      ----    ------            ----                 ----                -------
      Normal  SuccessfulCreate  19m                  cronjob-controller  Created job hello-1597160520
      Normal  SawCompletedJob   19m                  cronjob-controller  Saw completed job: hello-1597160520, status: Complete
      Normal  SuccessfulCreate  18m                  cronjob-controller  Created job hello-1597160580
      Normal  SawCompletedJob   18m                  cronjob-controller  Saw completed job: hello-1597160580, status: Complete
      Normal  SuccessfulCreate  17m                  cronjob-controller  Created job hello-1597160640
      Normal  SawCompletedJob   17m                  cronjob-controller  Saw completed job: hello-1597160640, status: Complete
      Normal  SuccessfulCreate  16m                  cronjob-controller  Created job hello-1597160700
      Normal  SuccessfulDelete  16m                  cronjob-controller  Deleted job hello-1597160520
      Normal  SawCompletedJob   16m                  cronjob-controller  Saw completed job: hello-1597160700, status: Complete
      Normal  SuccessfulCreate  15m                  cronjob-controller  Created job hello-1597160760
      Normal  SawCompletedJob   15m                  cronjob-controller  Saw completed job: hello-1597160760, status: Complete
      Normal  SuccessfulDelete  15m                  cronjob-controller  Deleted job hello-1597160580
      Normal  SuccessfulCreate  14m                  cronjob-controller  Created job hello-1597160820
      Normal  SuccessfulDelete  14m                  cronjob-controller  Deleted job hello-1597160640
      Normal  SawCompletedJob   14m                  cronjob-controller  Saw completed job: hello-1597160820, status: Complete
      Normal  SuccessfulCreate  13m                  cronjob-controller  Created job hello-1597160880
      Normal  SawCompletedJob   13m                  cronjob-controller  Saw completed job: hello-1597160880, status: Complete
    ………………
      Normal  SawCompletedJob   11m                  cronjob-controller  Saw completed job: hello-1597161000, status: Complete
      Normal  SuccessfulDelete  11m                  cronjob-controller  Deleted job hello-1597160820
      Normal  SawCompletedJob   10m                  cronjob-controller  (combined from similar events): Saw completed job: hello-1597161060, status: Complete
      Normal  SuccessfulCreate  4m13s (x7 over 10m)  cronjob-controller  (combined from similar events): Created job hello-1597161420

找到最后一次调度任务创建的 Pod， 并查看 Pod 的标准输出。请注意任务名称和 Pod 名称是不同的。

[root@k8s-master controller]# kubectl logs pod/hello-1590721740-rcx7v # 或者 kubectl logs hello-1590721740-rcx7v
    Fri May 29 03:09:04 UTC 2020
    Hello from the Kubernetes cluster

删除 CronJob

[root@k8s-master controller]# kubectl get cronjob
    NAME    SCHEDULE      SUSPEND   ACTIVE   LAST SCHEDULE   AGE
    hello   */1 * * * *   False     0        32s             19m
    [root@k8s-master controller]#
    [root@k8s-master controller]# kubectl delete cronjob hello # 或者 kubectl delete -f cronjob.yaml
    cronjob.batch "hello" deleted
    [root@k8s-master controller]# kubectl get cronjob # 可见已删除
    No resources found in default namespace.