CronJob YAML

Learn the CronJob YAML structure.

CronJob YAML

A CronJob's spec has a schedule and a jobTemplate; the jobTemplate is identical to a Job's spec (that's why three nested specs appear):

apiVersion: batch/v1
kind: CronJob
metadata:
  name: gece-yedek
spec:
  schedule: "0 3 * * *"
  jobTemplate:
    spec:
      template:
        spec:
          restartPolicy: OnFailure
          containers:
            - name: yedek
              image: postgres:16
              command: ["sh", "-c", "pg_dump -h db -U app app > /yedek/app.sql"]

Concurrency and history

Three important settings:

concurrencyPolicy: Allow (default), Forbid (skip if it overlaps the previous one), Replace (stop the previous one, start the new one).
startingDeadlineSeconds: a missed run can still be started within this time.
successfulJobsHistoryLimit / failedJobsHistoryLimit: the number of old Jobs kept (default 3 / 1).

spec:
  schedule: "0 3 * * *"
  timeZone: "Europe/Istanbul"
  concurrencyPolicy: Forbid
  successfulJobsHistoryLimit: 3
  failedJobsHistoryLimit: 5

Exercise A nightly backup

Write a CronJob YAML: name gece-yedek; schedule: "0 3 * * *"; concurrencyPolicy: Forbid; restartPolicy: OnFailure in the pod template inside jobTemplate; container named yedek, image postgres:16.

Show example solution

apiVersion: batch/v1
kind: CronJob
metadata:
  name: gece-yedek
spec:
  schedule: "0 3 * * *"
  concurrencyPolicy: Forbid
  jobTemplate:
    spec:
      template:
        spec:
          restartPolicy: OnFailure
          containers:
            - name: yedek
              image: postgres:16

Test yourself

What happens if the next run time arrives before the previous backup finishes?
- Both always run together
- The CronJob is deleted
- It errors
- It depends on concurrencyPolicy: Allow, Forbid or Replace
Show answer

It depends on concurrencyPolicy: Allow, Forbid or Replace — For jobs like backups, Forbid is chosen to prevent overlap.

Skip an overlapping run.

spec:
  schedule: "0 3 * * *"
  concurrencyPolicy: ____

Show answer

spec:
  schedule: "0 3 * * *"
  concurrencyPolicy: Forbid

Match.

Allow

Allow overlap
Forbid

Skip the overlapping one
Replace

Stop the old one
timeZone

Time zone

Next lesson: Summary - Job and CronJob

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