控制器 - Job - 控制器 - Job - 《Kubernates》

运行一个Job的例子

Kubernetes中的 Job 对象将创建一个或多个 Pod，并确保指定数量的 Pod 可以成功执行到进程正常结束：

当 Job 创建的 Pod 执行成功并正常结束时，Job 将记录成功结束的 Pod 数量
当成功结束的 Pod 达到指定的数量时，Job 将完成执行
删除 Job 对象时，将清理掉由 Job 创建的 Pod

一个简单的例子是：创建一个 Job 对象用来确保一个 Pod 的成功执行并结束。在第一个 Pod 执行失败或者被删除（例如，节点硬件故障或机器重启）的情况下，该 Job 对象将创建一个新的 Pod 以重新执行。

当然，您也可以使用 Job 对象并行执行多个 Pod。

运行一个Job的例子

在下面这个 Job 的例子中，Pod 执行了一个跟 π 相关的计算，并打印出最终结果，该计算大约需要 10 秒钟执行结束。

apiVersion: batch/v1
kind: Job
metadata:
  name: pi
spec:
  template:
    spec:
      containers:
      - name: pi
        image: perl
        command: ["perl",  "-Mbignum=bpi", "-wle", "print bpi(2000)"]
      restartPolicy: Never
  backoffLimit: 4

执行如下命令创建该对象： ```bash kubectl apply -f https://kuboard.cn/statics/learning/job/job.yaml


- <br />
- 执行命令查看创建结果
```bash
kubectl describe jobs/pi

输出结果如下

Name:             pi
Namespace:        default
Selector:         controller-uid=b1db589a-2c8d-11e6-b324-0209dc45a495
Labels:           controller-uid=b1db589a-2c8d-11e6-b324-0209dc45a495
                  job-name=pi
Annotations:      <none>
Parallelism:      1
Completions:      1
Start Time:       Tue, 07 Jun 2016 10:56:16 +0200
Pods Statuses:    0 Running / 1 Succeeded / 0 Failed
Pod Template:
  Labels:       controller-uid=b1db589a-2c8d-11e6-b324-0209dc45a495
                job-name=pi
  Containers:
  pi:
    Image:      perl
    Port:
    Command:
      perl
      -Mbignum=bpi
      -wle
      print bpi(2000)
    Environment:        <none>
    Mounts:             <none>
  Volumes:              <none>
Events:
  FirstSeen    LastSeen    Count    From            SubobjectPath    Type        Reason            Message
  ---------    --------    -----    ----            -------------    --------    ------            -------
  1m           1m          1        {job-controller }                Normal      SuccessfulCreate  Created pod: pi-dtn4q

执行以下命令可查看所有结束的 Pod ```bash kubectl get pods


   - <br />
   - 执行以下命令可获得该 Job 所有 Pod 的名字：
```bash
pods=$(kubectl get pods --selector=job-name=pi --output=jsonpath='{.items[*].metadata.name}')
echo $pods

输出结果如下

pi-aiw0a

在这个命令中：

  - selector 与 Job 定义中的 selector 相同
  - --output=jsonpath 选项指定了一个表达式，该表达式从返回结果列表中的每一个 Pod 的信息中定位出 name 字段的取值

执行以下命令可查看 Pod 的日志： ```bash kubectl logs $pods

<br />        输出结果如下：
```bash
3.1415926535897932384626433832795028841971693993751058209749445923078164062862089986280348253421170679821480865132823066470938446095505822317253594081284811174502841027019385211055596446229489549303819644288109756659334461284756482337867831652712019091456485669234603486104543266482133936072602491412737245870066063155881748815209209628292540917153643678925903600113305305488204665213841469519415116094330572703657595919530921861173819326117931051185480744623799627495673518857527248912279381830119491298336733624406566430860213949463952247371907021798609437027705392171762931767523846748184676694051320005681271452635608277857713427577896091736371787214684409012249534301465495853710507922796892589235420199561121290219608640344181598136297747713099605187072113499999983729780499510597317328160963185950244594553469083026425223082533446850352619311881710100031378387528865875332083814206171776691473035982534904287554687311595628638823537875937519577818577805321712268066130019278766111959092164201989380952572010654858632788659361533818279682303019520353018529689957736225994138912497217752834791315155748572424541506959508295331168617278558890750983817546374649393192550604009277016711390098488240128583616035637076601047101819429555961989467678374494482553797747268471040475346462080466842590694912933136770289891521047521620569660240580381501935112533824300355876402474964732639141992726042699227967823547816360093417216412199245863150302861829745557067498385054945885869269956909272107975093029553211653449872027559602364806654991198818347977535663698074265425278625518184175746728909777727938000816470600161452491921732172147723501414419735685481613611573525521334757418494684385233239073941433345477624168625189835694855620992192221842725502542568876717904946016534668049886272327917860857843838279679766814541009538837863609506800642251252051173929848960841284886269456042419652850222106611863067442786220391949450471237137869609563643719172874677646575739624138908658326459958133904780275901