前言
容器分爲兩類
-
在線業務 - 服務類容器
需要持續不中斷的提供服務,容器需要一直運行
-
離線業務 - 工作類容器
一般執行一次性任務,比如統計日誌數據等,運行完成後容器即可關閉
更新歷史
- 20200618 - 初稿 - 左程立
- 原文地址 - https://blog.zuolinux.com/2020/06/18/controller-job-cronjob.html
Job
cat job.yaml
apiVersion: batch/v1
kind: Job
metadata:
name: job-test
spec:
template:
metadata:
name: job-test
spec:
containers:
- name: test-job
image: busybox
command: ["echo", "test job!"]
restartPolicy: Never
參數 restartPolicy 只能是 Never 或者 onFailure
啓動
[root@master01 ~]# kubectl apply -f job.yaml
job.batch/job-test created
運行狀態
[root@master01 ~]# kubectl get pod
NAME READY STATUS RESTARTS AGE
job-test-t2gbw 0/1 ContainerCreating 0 12s
[root@master01 ~]# kubectl get pod
NAME READY STATUS RESTARTS AGE
job-test-t2gbw 0/1 Completed 0 24s
查看運行結果
[root@master01 ~]# kubectl logs job-test-t2gbw
test job!
Job 執行失敗如何處理
將 command 胡亂設置導致 job 無法成功啓動
command: ["echo123", "test job!"]
restartPolicy: Never
當 restartPolicy: Never 時,可以看到 k8s 在不斷的開新的 pod 但不會讓它一直開下去,默認參數 spec.backoffLimit: 6 會進行阻止
[root@master01 ~]# kubectl get pod
NAME READY STATUS RESTARTS AGE
job-test-2zrt4 0/1 ContainerCannotRun 0 87s
job-test-5z884 0/1 ContainerCannotRun 0 77s
job-test-cxgmm 0/1 ContainerCannotRun 0 107s
job-test-nt9gt 0/1 ContainerCannotRun 0 57s
job-test-wxv7l 0/1 ContainerCreating 0 17s
當 restartPolicy: OnFailure 時,k8s 不開新 pod,只會不斷重啓 pod
[root@master01 ~]# kubectl get pod
NAME READY STATUS RESTARTS AGE
job-test-bd695 0/1 CrashLoopBackOff 4 3m15s
如果 job 沒有報錯,但是它一直不結束怎麼辦?
參數 spec.activeDeadlineSeconds: 100 會在 100s 後將 Job 中所有 Pod 進行關閉
此時 Pod 關閉狀態爲 reason: DeadlineExceeded
並行 Job
cat job.yaml
apiVersion: batch/v1
kind: Job
metadata:
name: job-test
spec:
parallelism: 2
......
參數 parallelism: 2 僅允許最多兩個 Pod 同時運行
查看運行情況
[root@master01 ~]# kubectl get pod
NAME READY STATUS RESTARTS AGE
job-test-6ttz9 0/1 ContainerCreating 0 8s
job-test-mknjc 0/1 ContainerCreating 0 8s
[root@master01 ~]# kubectl get pod
NAME READY STATUS RESTARTS AGE
job-test-6ttz9 0/1 Completed 0 68s
job-test-mknjc 0/1 Completed 0 68s
[root@master01 ~]# kubectl get job
NAME COMPLETIONS DURATION AGE
job-test 0/1 of 2 10s 10s
[root@master01 ~]# kubectl get job
NAME COMPLETIONS DURATION AGE
job-test 2/1 of 2 19s 66s
增加參數 completions
apiVersion: batch/v1
kind: Job
metadata:
name: job-test
spec:
parallelism: 2
completions: 8
參數 completions: 8 表示至少成功運行 8 個 pod 如果不是8個成功,那麼會根據 restartPolicy 的策略進行處理 可以認爲是一種檢查機制
查看運行情況
[root@master01 ~]# kubectl get pod
NAME READY STATUS RESTARTS AGE
job-test-6xwpt 0/1 ContainerCreating 0 8s
job-test-grk4q 0/1 ContainerCreating 0 8s
[root@master01 ~]# kubectl get job
NAME COMPLETIONS DURATION AGE
job-test 0/8 11s 11s
[root@master01 ~]# kubectl get job
NAME COMPLETIONS DURATION AGE
job-test 6/8 76s 76s
[root@master01 ~]# kubectl get pod
NAME READY STATUS RESTARTS AGE
job-test-2jxqx 0/1 Completed 0 28s
job-test-6xwpt 0/1 Completed 0 90s
job-test-gndq7 0/1 Completed 0 70s
job-test-grk4q 0/1 Completed 0 90s
job-test-n96k6 0/1 Completed 0 70s
job-test-np4n7 0/1 Completed 0 49s
job-test-scc9c 0/1 Completed 0 28s
job-test-zcnbp 0/1 Completed 0 49s
[root@master01 ~]# kubectl get job
NAME COMPLETIONS DURATION AGE
job-test 8/8 82s 91s
CronJob
CronJob 會定時 create 一個 job 對象
cat cronjob.yaml
apiVersion: batch/v1beta1
kind: CronJob
metadata:
name: hello
spec:
schedule: "*/1 * * * *"
jobTemplate:
spec:
template:
spec:
containers:
- name: hello
image: busybox
command: ["echo","test cron job!"]
restartPolicy: OnFailure
查看運行結果
[root@master01 ~]# kubectl get cronjob
NAME SCHEDULE SUSPEND ACTIVE LAST SCHEDULE AGE
hello */1 * * * * False 0 67s 3m45s
[root@master01 ~]# kubectl get jobs
NAME COMPLETIONS DURATION AGE
hello-1595319480 1/1 27s 3m23s
hello-1595319540 1/1 19s 2m23s
hello-1595319600 1/1 24s 83s
hello-1595319660 0/1 22s 22s
[root@master01 ~]# kubectl get pod
NAME READY STATUS RESTARTS AGE
hello-1595319480-2kl8h 0/1 Completed 0 3m21s
hello-1595319540-gwthv 0/1 Completed 0 2m21s
hello-1595319600-54548 0/1 Completed 0 81s
hello-1595319660-8xqn6 0/1 ContainerCreating 0 20s
可以看到,就是把前面說過的 Job 對象進行定時的運行。
結束語
Job/CronJob 控制器可以進行離線業務的處理,不需要長期運行一個 Pod。
這類控制器管理的 Pod 不對外提供持續在線服務,任務運行完成後,即會將容器進行關閉,可以用於一些定時數據處理類的工作。
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