Bits of .NET

⏰ CronJobs = Scheduled Tasks

Regular tasks need automation. CronJobs schedule tasks in Kubernetes. Backups, cleanup, reports — automatic.

📝 CronJob Setup

apiVersion: batch/v1
kind: CronJob
metadata:
    name: daily-backup
spec:
    schedule: "0 2 * * *"  # Daily at 2 AM
    jobTemplate:
        spec:
            template:
                spec:
                    containers:
                    - name: backup
                        image: alpine:latest
                        command:
                        - /bin/sh
                        - -c
                        - |
                            echo "Running backup at $(date)"
                            # Backup command here
                    restartPolicy: OnFailure

# Cron Schedule Format
# ┌───────────── minute (0 - 59)
# │ ┌───────────── hour (0 - 23)
# │ │ ┌───────────── day of month (1 - 31)
# │ │ │ ┌───────────── month (1 - 12)
# │ │ │ │ ┌───────────── day of week (0 - 6)
# │ │ │ │ │
# * * * * *

🎯 CronJob Examples

# Daily backup with retention
apiVersion: batch/v1
kind: CronJob
metadata:
    name: db-backup
spec:
    schedule: "0 3 * * *"
    successfulJobsHistoryLimit: 3
    failedJobsHistoryLimit: 3
    jobTemplate:
        spec:
            template:
                spec:
                    containers:
                    - name: backup
                        image: postgres:15
                        command:
                        - /bin/sh
                        - -c
                        - |
                            pg_dump -h postgres-service -U postgres -d mydb > /backup/backup.sql
                            gzip /backup/backup.sql
                    restartPolicy: OnFailure

# Cleanup job (weekly)
apiVersion: batch/v1
kind: CronJob
metadata:
    name: clean-temp
spec:
    schedule: "0 4 * * 0"  # Sunday at 4 AM
    jobTemplate:
        spec:
            template:
                spec:
                    containers:
                    - name: cleaner
                        image: busybox
                        command:
                        - /bin/sh
                        - -c
                        - |
                            echo "Cleaning temp files..."
                            rm -rf /tmp/*
                    restartPolicy: OnFailure

# Health check job
apiVersion: batch/v1
kind: CronJob
metadata:
    name: health-check
spec:
    schedule: "*/30 * * * *"  # Every 30 minutes
    jobTemplate:
        spec:
            template:
                spec:
                    containers:
                    - name: health
                        image: curlimages/curl
                        command:
                        - curl
                        - -f
                        - http://web-service/health
                    restartPolicy: OnFailure

# Commands
kubectl get cronjobs
kubectl get jobs
kubectl logs job/daily-backup-xxxxx
kubectl delete cronjob daily-backup

💡 CronJob Tips

• Set appropriate schedule
• Limit successful/failed history
• Monitor job completion
• Log job outputs
• Handle failures gracefully