《OpenShift 4.x HOL教程汇总》

在Kubernetes中分贝使用Job和CronJob实现一次性运行的任务和定时运行的的任务，他们分别被Kubernetes的JobController和CronJobController控制器所控制，而这些任务都是通过Pod运行的。
在创建Job和CronJob对象的时候，既可以使用定义对象的YAML文件，还可使用命令直接创建。需要注意的是，从OpenShift 4.5开始，在使用oc命令创建Job和CronJob对象的时候只能使用“oc create job”和“oc create cronjob”命令。而原有“oc run”命令已经不能创建Job和CronJob对象了，它只能运行1个指定pod。

通过YAML创建

创建Job

1. 创建项目

$ oc create project myjob

2. 在OpenShift控制台的项目中直接运行以下创建Job的YAML脚本。
   

apiVersion: batch/v1
kind: Job
metadata:
  name: pi
spec:
  parallelism: 1    
  completions: 1    
  activeDeadlineSeconds: 1800 
  backoffLimit: 6   
  template:         
    metadata:
      name: pi
    spec:
      containers:
      - name: pi
        image: perl
        command: ["perl",  "-Mbignum=bpi", "-wle", "print bpi(2000)"]
      restartPolicy: OnFailure

3. 查看job和pod，在pod为“Completed”状态后查看它的日志。注意：从对象名称可以看出， 这种方法是先创建Job对象，然后再通过有Job对象生成的对应Pod对象。

$ oc get job
NAME                   COMPLETIONS   DURATION   AGE
pi                     1/1           33s        7m37s 
 
$ oc get pod
NAME                         READY   STATUS              RESTARTS   AGE
pi-kxdcr                     0/1     Completed           0          7m40s
$ oc logs pod/pi-kxdcr
3.1415926535897932384626433832795028841971693993751058209749445923078164062862089986280348253421170679821480865132823066470938446095505822317253594081284811174502841027019385211055596446229489549303819644288109756659334461284756482337867831652712019091456485669234603486104543266482133936072602491412737245870066063155881748815209209628292540917153643678925903600113305305488204665213841469519415116094330572703657595919530921861173819326117931051185480744623799627495673518857527248912279381830119491298336733624406566430860213949463952247371907021798609437027705392171762931767523846748184676694051320005681271452635608277857713427577896091736371787214684409012249534301465495853710507922796892589235420199561121290219608640344181598136297747713099605187072113499999983729780499510597317328160963185950244594553469083026425223082533446850352619311881710100031378387528865875332083814206171776691473035982534904287554687311595628638823537875937519577818577805321712268066130019278766111959092164201989380952572010654858632788659361533818279682303019520353018529689957736225994138912497217752834791315155748572424541506959508295331168617278558890750983817546374649393192550604009277016711390098488240128583616035637076601047101819429555961989467678374494482553797747268471040475346462080466842590694912933136770289891521047521620569660240580381501935112533824300355876402474964732639141992726042699227967823547816360093417216412199245863150302861829745557067498385054945885869269956909272107975093029553211653449872027559602364806654991198818347977535663698074265425278625518184175746728909777727938000816470600161452491921732172147723501414419735685481613611573525521334757418494684385233239073941433345477624168625189835694855620992192221842725502542568876717904946016534668049886272327917860857843838279679766814541009538837863609506800642251252051173929848960841284886269456042419652850222106611863067442786220391949450471237137869609563643719172874677646575739624138908658326459958133904780275901

创建CronJob

1. 在OpenShift控制台的项目中直接运行以下创建CronJob的YAML脚本。
   

apiVersion: batch/v1
kind: CronJob
metadata:
  name: hello-job
spec:
  schedule: "*/1 * * * *"
  jobTemplate:
    spec:
      template:
        spec:
          containers:
          - name: hello
            image: busybox
            args:
            - /bin/sh
            - -c
            - date; echo Hello from the Kubernetes cluster
          restartPolicy: OnFailure

2. 通过命令行或控制台查看创建的hello-job。

$ oc get cronjob -n myjob
NAME        SCHEDULE      SUSPEND   ACTIVE   LAST SCHEDULE   AGE
hello-job   */1 * * * *   False     1        7s              14m

3. 查看hello-job的详细信息。注意下方有和该对象相关的Events，从时间轴可以看出，当需要创建第4个Pod运行Job的时候，OpenShift删删掉第一个创建Pod。这样就一直保持运行hello-job的Pod数量最多为3个，这和hello-job对象的“Successful Job History Limit”参数定义的是一致的。

$ oc describe  cronjob hello-job -n myjob
Name:                          hello-job
Namespace:                     myjob
Labels:                        <none>
Annotations:                   <none>
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:      busybox
    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:  Thu, 03 Sep 2020 03:47:00 +0000
Active Jobs:         <none>
Events:
  Type    Reason            Age                    From                Message
  ----    ------            ----                   ----                -------
  Normal  SuccessfulCreate  15m                    cronjob-controller  Created job hello-job-1599103920
  Normal  SawCompletedJob   15m                    cronjob-controller  Saw completed job: hello-job-1599103920, status: Complete
  Normal  SuccessfulCreate  14m                    cronjob-controller  Created job hello-job-1599103980
  Normal  SawCompletedJob   14m                    cronjob-controller  Saw completed job: hello-job-1599103980, status: Complete
  Normal  SuccessfulCreate  13m                    cronjob-controller  Created job hello-job-1599104040
  Normal  SawCompletedJob   13m                    cronjob-controller  Saw completed job: hello-job-1599104040, status: Complete
  Normal  SuccessfulCreate  12m                    cronjob-controller  Created job hello-job-1599104100
  Normal  SuccessfulDelete  12m                    cronjob-controller  Deleted job hello-job-1599103920
  Normal  SawCompletedJob   12m                    cronjob-controller  Saw completed job: hello-job-1599104100, status: Complete
  Normal  SuccessfulCreate  11m                    cronjob-controller  Created job hello-job-1599104160
  Normal  SawCompletedJob   11m                    cronjob-controller  Saw completed job: hello-job-1599104160, status: Complete
  Normal  SuccessfulDelete  11m                    cronjob-controller  Deleted job hello-job-1599103980
  Normal  SuccessfulCreate  10m                    cronjob-controller  Created job hello-job-1599104220
  Normal  SuccessfulDelete  10m                    cronjob-controller  Deleted job hello-job-1599104040
  Normal  SawCompletedJob   10m                    cronjob-controller  Saw completed job: hello-job-1599104220, status: Complete
  Normal  SuccessfulCreate  9m50s                  cronjob-controller  Created job hello-job-1599104280
  Normal  SawCompletedJob   9m40s                  cronjob-controller  Saw completed job: hello-job-1599104280, status: Complete
  Normal  SuccessfulDelete  9m40s                  cronjob-controller  Deleted job hello-job-1599104100
  Normal  SuccessfulCreate  8m49s                  cronjob-controller  Created job hello-job-1599104340
  Normal  SawCompletedJob   8m39s                  cronjob-controller  Saw completed job: hello-job-1599104340, status: Complete
  Normal  SuccessfulDelete  8m39s                  cronjob-controller  Deleted job hello-job-1599104160
  Normal  SuccessfulCreate  7m49s                  cronjob-controller  Created job hello-job-1599104400
  Normal  SawCompletedJob   7m39s                  cronjob-controller  Saw completed job: hello-job-1599104400, status: Complete
  Normal  SuccessfulDelete  7m39s                  cronjob-controller  Deleted job hello-job-1599104220
  Normal  SawCompletedJob   5m37s (x2 over 6m38s)  cronjob-controller  (combined from similar events): Saw completed job: hello-job-1599104520, status: Complete
  Normal  SuccessfulCreate  43s (x7 over 6m48s)    cronjob-controller  (combined from similar events): Created job hello-job-1599104820

4. 在OpenShift控制台的hello-job中查看相关的Event。
   
5. 查看运行的job数量。

$ oc get job -n myjob
NAME                   COMPLETIONS   DURATION   AGE
hello-job-1599105120   1/1           7s         3m3s
hello-job-1599105180   1/1           8s         2m2s
hello-job-1599105240   1/1           7s         61s
hello-job-1599105300   0/1                      0s

6. 查看运行的pod数量，它和job数量一致，同时最多保持3个Pod。

$ oc get pod -n myjob
NAME                         READY   STATUS              RESTARTS   AGE
hello-job-1599104580-b2gqw   0/1     Completed           0          3m8s
hello-job-1599104640-kv9ml   0/1     Completed           0          2m8s
hello-job-1599104700-g2jmv   0/1     Completed           0          67s
hello-job-1599104760-dtwz6   0/1     ContainerCreating   0          6s

使用命令

创建Job

1. 运行以下命令，创建运行Job的Pod。

$ oc create job pi --image=perl -- perl -Mbignum=bpi -wle 'print bpi(2000)'

2. 查看Job和Pod对象。注意：从查到的对象可以看出， 这种方法是是直接生成Pod对象并运行，而没有创建Job对象。

$ oc get job

$ oc get pod
NAME                         READY   STATUS      RESTARTS   AGE
pi-job                       0/1     Completed   0          33s

创建CronJob

1. 执行命令，创建CronJob。注意：当有“–schedule=’*/1 * * * *’”参数的时候，会自动生成CronJob对象。而Job对象是由CronJob对象生成的。

$ oc create cronjob pi --image=perl --schedule='*/1 * * * *' -- perl -Mbignum=bpi -wle 'print bpi(2000)'

2. 查看CronJob