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Jobs and CronJobs

Jobs​

A Job creates one or more Pods and ensures that a specified number of them successfully terminate.

  • Pods are not restarted once they complete successfully
  • If a Pod fails, the Job creates a new Pod to replace it
  • When the specified number of completions is reached, the Job is complete
  • Deleting a Job cleans up the Pods it created
More Information

Example​

apiVersion: batch/v1
kind: Job
metadata:
  name: data-migration
spec:
  completions: 1
  backoffLimit: 3
  template:
    spec:
      containers:
      - name: migrate
        image: my-app:latest
        command: ["python", "migrate.py"]
      restartPolicy: Never

Configuration​

  • completions: number of Pods that must complete successfully (default: 1)
  • parallelism: number of Pods that can run in parallel (default: 1)
  • backoffLimit: number of retries before marking the Job as failed (default: 6)
  • activeDeadlineSeconds: maximum time the Job can run before being terminated
  • restartPolicy: must be Never or OnFailure (not Always)

CronJobs​

A CronJob creates Jobs on a repeating schedule using cron syntax.

  • Schedule format: minute hour day-of-month month day-of-week
  • Useful for periodic tasks like backups, report generation, and cleanup
More Information

Example​

apiVersion: batch/v1
kind: CronJob
metadata:
  name: nightly-backup
spec:
  schedule: "0 2 * * *"
  jobTemplate:
    spec:
      template:
        spec:
          containers:
          - name: backup
            image: backup-tool:latest
            command: ["backup.sh"]
          restartPolicy: OnFailure

Configuration​

  • concurrencyPolicy: how to handle concurrent Jobs
    • Allow (default): allows concurrent Jobs
    • Forbid: skips the new Job if the previous one is still running
    • Replace: cancels the current Job and starts a new one
  • startingDeadlineSeconds: deadline for starting the Job if it misses the scheduled time
  • successfulJobsHistoryLimit: number of completed Jobs to keep (default: 3)
  • failedJobsHistoryLimit: number of failed Jobs to keep (default: 1)
More Information