CronJobs

• CronJob → creates Job → creates Pod on schedule
• spec.schedule: cron expression (* * * * * = every minute)
• spec.jobTemplate: Job template (not Pod directly)

CronJob YAML

apiVersion: batch/v1
kind: CronJob
metadata:
  name: backup
spec:
  schedule: "0 2 * * *"          # 2am every day
  concurrencyPolicy: Forbid
  successfulJobsHistoryLimit: 3
  failedJobsHistoryLimit: 1
  startingDeadlineSeconds: 200
  jobTemplate:
    spec:
      backoffLimit: 3
      completions: 3
      parallelism: 1
      activeDeadlineSeconds: 300
      template:
        spec:
          restartPolicy: OnFailure
          containers:
          - name: backup
            image: backup-tool:1.0
            args: ["/bin/sh", "-c", "echo $(date)"]

Concurrency policy

Key fields

Imperative commands

kubectl create cronjob mycron --image=busybox --schedule='*/5 * * * *' -- date
kubectl create job manual-run --from=cronjob/backup
kubectl get cronjobs
kubectl get jobs,po

Exam gotchas

• Cron syntax: minute hour day-of-month month day-of-week; */5 * * * * = every 5 minutes
• restartPolicy: Never → new pod on failure; OnFailure → restarts same pod
• Manual trigger: kubectl create job manual --from=cronjob/<name>

Practice scenario: Jobs and CronJobs

Tasks

• Job data-export: busybox, echo exported, 3 completions, 2 parallel, backoffLimit: 2
• CronJob nightly-report: same, midnight daily, concurrencyPolicy: Forbid
• Manually trigger the CronJob once and verify

cat <<EOF | kubectl apply -f -
apiVersion: batch/v1
kind: Job
metadata:
  name: data-export
spec:
  completions: 3
  parallelism: 2
  backoffLimit: 2
  template:
    spec:
      restartPolicy: Never
      containers:
      - name: export
        image: busybox
        command: ["echo", "exported"]
EOF

kubectl create cronjob nightly-report --image=busybox --schedule='0 0 * * *' -- echo exported
kubectl patch cronjob nightly-report -p '{"spec":{"concurrencyPolicy":"Forbid"}}'

kubectl create job manual-trigger --from=cronjob/nightly-report
kubectl get jobs,pods