Jobs and CronJobs

Jobs and CronJobs — Running Tasks

A Job creates one or more pods and ensures that a specified number of them successfully terminate. When a Job completes, the pods are not restarted.

A CronJob creates Jobs on a repeating schedule — like a cron job on a Linux system.

Jobs

apiVersion: batch/v1
kind: Job
metadata:
  name: pi
spec:
  completions: 1
  parallelism: 1
  template:
    spec:
      containers:
        - name: pi
          image: perl
          command: ["perl", "-Mbignum=bpi", "-wle", "print bpi(2000)"]
      restartPolicy: Never
  backoffLimit: 4

completions — How many pods need to successfully finish.

parallelism — How many pods can run at the same time.

backoffLimit — How many times to retry before marking the Job as failed.

restartPolicy: Never — Failed pods are not restarted; new ones are created instead.

CronJobs

apiVersion: batch/v1
kind: CronJob
metadata:
  name: database-backup
spec:
  schedule: "0 2 * * *"   # Every day at 2 AM
  jobTemplate:
    spec:
      template:
        spec:
          containers:
            - name: backup
              image: my-backup-image
              command: ["/bin/sh", "-c", "backup-script.sh"]
          restartPolicy: OnFailure
  successfulJobsHistoryLimit: 3
  failedJobsHistoryLimit: 1

schedule — Standard cron format: minute, hour, day, month, weekday.

successfulJobsHistoryLimit — How many completed Jobs to keep for debugging.

failedJobsHistoryLimit — How many failed Jobs to keep.

Managing Jobs and CronJobs

# Run a Job
kubectl apply -f job.yaml

# Check Job status
kubectl get jobs
kubectl describe job pi

# View pod logs
kubectl logs job/pi

# Create a CronJob
kubectl apply -f cronjob.yaml

# Manually trigger a CronJob (bypass the schedule)
kubectl create job manual-backup --from=cronjob/database-backup

# Delete a CronJob
kubectl delete cronjob database-backup

Common Use Cases

Database backups — Run a backup script every night.

Data processing — Process a batch of records and terminate.

Report generation — Generate PDF reports on a schedule.

Cleanup tasks — Remove old logs or temporary files periodically.