Kubernetes Jobs and Cronjobs

 

CronJob’ , . CronJob’ Job’ (, - , ) , , Job , , , . Job’ Kubernetes (workloads).

Kubernetes : ReplicaSets, DaemonSets, Deployments StatefulSets. . , . (node), , .

, , ? , , . (backup, ) - , . . , , (exit status), , .

Job’ Kubernetes

Job’ Kubernetes:

1. : // . .

   
   
   
   
   

2. / : , /, .

   
   
   
   
   

Job’ Kubernetes , . , Job . Job , .

Kubernetes Job

Job’ Kubernetes, Kubernetes, (definition file). , job.yaml. :

apiVersion: batch/v1
kind: Job
metadata:
name: hello-world
spec:
template:
  metadata:
    name: hello-world
  spec:
    containers:
    - name: hello-world
      image: busybox
      command: ["echo", "Running a hello-world job"]
    restartPolicy: OnFailure
      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

Kubernetes, Kubernetes kubectl. :

$ kubectl apply -f job.yaml
job.batch/hello-world created
      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

, :

$ kubectl get pods
NAME              	READY    STATUS          RESTARTS      AGE
hello-world-mstmc        0/1 	ContainerCreating   0          1s
      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

job’ kubectl:

kubectl get jobs hello-world-mstmc
NAME            COMPLETIONS     DURATION     AGE
hello-world-mstmc   1/1           21s        27s
      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

:

$ kubectl get pods
NAME              	READY   STATUS  	RESTARTS       AGE
hello-world-mstmc       0/1 	Completed          0           25s
      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

, . Completed, job . Job, , :) - echo “Running a hello-world job” .

, , job , :

kubectl logs -f hello-world-mstmc
Running a hello-world job
      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

  , , .. “Running a hello-world job”. Job .

CronJob  

, cronjob . , job cronjob’.

, , cronjob , .

kubectl create job --from=cronjob/kubernetes-cron-job manual-cron-job
      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

--from=cronjob/kubernetes-cron-job



cronjob’ job manual-cron-job

Job’ Kubernetes (Cleanup)

Job Kubernetes , Job, . . , - , Job .

Job kubectl :

kubectl delete jobs job_name

Job  . Kubernetes, Job, , cascade=false



. :

kubectl delete jobs job_name cascade=false

, job’/cronjob’ kubernetes . .

1. failedJobHistoryLimit successfulJobsHistoryLimit:   job’ . , , job’. ,

failedJobHistoryLimit: 5
successfulJobsHistoryLimit: 10
      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

2. backoffLimit: .

RestartPolicy Job’ Kubernetes

restartPolic



y ( ) “always” (). Job . , restartPolicy



“Never” () “OnFailure” ( ).

Job’ Kubernetes

Job’ , , , Job’ Kubernetes spec.activeDeadlineSeconds



. Job’ .

, .spec.backoffLimit



, .. Job  , . .

Job backoff limit



, deadline



:

apiVersion: batch/v1
kind: Job
metadata:
 name: data-consumer
spec:
 backoffLimit: 5
 activeDeadlineSeconds: 20
 template:
spec:
    containers:
    - name: consumer
        image: busybox
        command: ["/bin/sh", "-c"]
        args: ["echo 'Consuming data'; sleep 1; exit 1"]
    restartPolicy: OnFailure
      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

Job’

, , Job, “run-once”. .

Job’

, , . job’, , . Job’ Kubernetes, .spec.completions - ( , ). Job (completions). Job , . . , :

apiVersion: batch/v1
kind: Job
metadata:
name: data-consumer
spec:
completions: 5
template:
 metadata:
   name: data-consumer
 spec:
   containers:
   - name: data-consumer
     image: busybox
     command: ["/bin/sh","-c"]
     args: ["echo 'consuming a message from queue'; sleep 5"]
   restartPolicy: OnFailure
      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

• completions 5.

  
  
  
  
  

Job’ (Work Queue)

job’, , , . , data science .

, :

apiVersion: batch/v1
kind: Job
metadata:
name: data-consumer
spec:
parallelism: 5
template:
 metadata:
   name: data-consumer
 spec:
   containers:
   - name: data-consumer
     image: busybox
     command: ["/bin/sh","-c"]
     args: ["echo 'consuming a message from queue'; sleep $(shuf -i 5-10 -n 1)"]
   restartPolicy: OnFailure
      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

.spec.completions



. parallelism



. completions



parallelism



(5). Job : 

5 , Job. , , Job . , Job .

Kubernetes Job 5 . , , . , (, AWS SQS). , Job , . :

• .

  
  
  
  
  

• .

  
  
  
  
  

, , ( 5 10), . , , , API.

CronJob’ 

Cronjob job (schedule). «», job’ . , . , job’ .

startingDeadlineSeconds



( ) concurrencyPolicy



Allow, job .

CronJob’ CronJob , . 100, job .

Cannot determine if job needs to be started. Too many missed start time (> 100). Set or decrease .spec.startingDeadlineSeconds or check clock skew.
      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

, startingDeadlineSeconds



(.. nil



), job’ startingDeadlineSeconds



, . ,   startDeadlineSeconds



200



, , job’ 200 .

CronJob , . , concurrencyPolicy



Forbid



CronJob , .

, , CronJob Job 08:30:00



, startingDeadlineSeconds



. CronJob 08:29:00



10:21:00



, job , job’ 100.

, , CronJob Job 08:30:00



startingDeadlineSeconds



200 . CronJob , ( 08:29:00



10:21:00



), Job 10:22:00. , , 200 (. . 3 ), , .

CronJob Job’, , Job, , .

TL;DR (Too Long; Didn’t Read)

• Job’ Kubernetes , , , .

  
  
  
  
  

• Job’ Kubernetes ; Job .

  
  
  
  
  

• restartPolicy
  
  
  
  Job «Never» «OnFailure»

  
  
  
  
  

• Job’ completions parallelism , . Job’ , , .

  
  
  
  
  

• Job’ , .spec.backoffLimit
  
  
  
  . .

  
  
  
  
  

• job’, .spec.activeDeadlineSeconds
  
  
  
  . backoffLimit
  
  
  
  . , Job , .

  
  
  
  
  

• Job’ . ttlSecondsAfterFinished
  
  
  
  , alpha.

  
  
  
  
  

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