Challenge - CronJob

Write a CronJob that runs daily.

Challenge: a safe scheduled backup

You'll write a CronJob that takes a backup of the database every night. Requirements:

Every day at 02:30 (Istanbul time)
A new one mustn't start if the previous backup hasn't finished
At most 2 attempts, at most 30 minutes
The backup is written to a PVC; the password comes from a Secret

pg_dump -h db -U app app | gzip > /yedek/app-$(date +%F).sql.gz

Exercise The top of the CronJob

Write the top part of a CronJob's spec section (starting with spec:): schedule: "30 2 * * *", timeZone: "Europe/Istanbul", concurrencyPolicy: Forbid; under jobTemplate.spec, backoffLimit: 1 and activeDeadlineSeconds: 1800.

Show example solution

spec:
  schedule: "30 2 * * *"
  timeZone: "Europe/Istanbul"
  concurrencyPolicy: Forbid
  jobTemplate:
    spec:
      backoffLimit: 1
      activeDeadlineSeconds: 1800

Exercise The backup pod template

Write the same CronJob's pod template spec section (starting with spec:): restartPolicy: OnFailure; a yedek volume from the yedekler PVC; container named yedek, image postgres:16; the PGPASSWORD variable from the POSTGRES_PASSWORD key of the db-gizli Secret; mount yedek at /yedek.

Show example solution

spec:
  restartPolicy: OnFailure
  volumes:
    - name: yedek
      persistentVolumeClaim:
        claimName: yedekler
  containers:
    - name: yedek
      image: postgres:16
      env:
        - name: PGPASSWORD
          valueFrom:
            secretKeyRef:
              name: db-gizli
              key: POSTGRES_PASSWORD
      volumeMounts:
        - name: yedek
          mountPath: /yedek

Test yourself

What is the most reliable way to notice a failed backup?
- Deleting the CronJob
- Setting an alert on the Job's failed state or the last success time
- Checking the logs by hand every morning
- Doing nothing
Show answer

Setting an alert on the Job's failed state or the last success time — The kube_cronjob_status_last_successful_time metric suits this.

Set the schedule's time zone to Istanbul.

spec:
  schedule: "30 2 * * *"
  timeZone: ____

Show answer

spec:
  schedule: "30 2 * * *"
  timeZone: "Europe/Istanbul"

Match.

"30 2 * * *"

Every day 02:30
Forbid

Prevent overlap
backoffLimit: 1

At most 2 attempts
activeDeadlineSeconds: 1800

30-minute limit

Next lesson: Challenge - RBAC

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