Kubernetes Jobs and CronJobs for batch workloads

# === One-off Job: Database migration ===
apiVersion: batch/v1
kind: Job
metadata:
  name: db-migrate
  namespace: production
spec:
  ttlSecondsAfterFinished: 3600    # Auto-cleanup after 1 hour
  backoffLimit: 3                   # Retry up to 3 times on failure
  activeDeadlineSeconds: 600        # Timeout after 10 minutes
  template:
    metadata:
      labels:
        app: db-migrate
    spec:
      restartPolicy: Never           # Don't restart — let Job controller handle retries
      serviceAccountName: migration-runner
      containers:
        - name: migrate
          image: myapp:latest
          command: ["rails", "db:migrate"]
          envFrom:
            - secretRef:
                name: database-credentials
          resources:
            requests:
              cpu: 250m
              memory: 512Mi
            limits:
              cpu: "1"
              memory: 1Gi
---
# === Parallel Job: Process items in batch ===
apiVersion: batch/v1
kind: Job
metadata:
  name: batch-processor
  namespace: production
spec:
  completions: 10           # Total items to process
  parallelism: 3            # Run 3 pods at a time
  backoffLimit: 5
  template:
    spec:
      restartPolicy: Never
      containers:
        - name: processor
          image: myapp-worker:latest
          command: ["python", "process_batch.py"]
          env:
            - name: BATCH_SIZE
              value: "100"
            - name: JOB_COMPLETION_INDEX
              valueFrom:
                fieldRef:
                  fieldPath: metadata.annotations['batch.kubernetes.io/job-completion-index']
---
# === CronJob: Nightly database backup ===
apiVersion: batch/v1
kind: CronJob
metadata:
  name: db-backup
  namespace: production
spec:
  schedule: "0 2 * * *"              # Daily at 2:00 AM UTC
  timeZone: "America/New_York"        # K8s 1.27+
  concurrencyPolicy: Forbid           # Don't run if previous is still running
  successfulJobsHistoryLimit: 7       # Keep last 7 successful runs
  failedJobsHistoryLimit: 3           # Keep last 3 failed runs
  startingDeadlineSeconds: 300        # Skip if missed by > 5 min
  jobTemplate:
    spec:
      ttlSecondsAfterFinished: 86400
      backoffLimit: 2
      template:
        spec:
          restartPolicy: OnFailure
          volumes:
            - name: backup-storage
              persistentVolumeClaim:
                claimName: backup-pvc
          containers:
            - name: backup
              image: postgres:16-alpine
              command:
                - /bin/sh
                - -c
                - |
                  TIMESTAMP=$(date +%Y%m%d-%H%M%S)
                  FILENAME="backup-${TIMESTAMP}.sql.gz"
                  echo "Starting backup: ${FILENAME}"
                  pg_dump "$DATABASE_URL" | gzip > "/backups/${FILENAME}"
                  echo "Backup complete: $(ls -lh /backups/${FILENAME})"
                  # Prune backups older than 30 days
                  find /backups -name "backup-*.sql.gz" -mtime +30 -delete
              envFrom:
                - secretRef:
                    name: database-credentials
              volumeMounts:
                - name: backup-storage
                  mountPath: /backups
              resources:
                requests:
                  cpu: 250m
                  memory: 512Mi
                limits:
                  cpu: "1"
                  memory: 2Gi
---
# === CronJob: Cache warm-up every 5 minutes ===
apiVersion: batch/v1
kind: CronJob
metadata:
  name: cache-warmer
  namespace: production
spec:
  schedule: "*/5 * * * *"
  concurrencyPolicy: Replace          # Kill old one if new one starts
  successfulJobsHistoryLimit: 1
  failedJobsHistoryLimit: 1
  jobTemplate:
    spec:
      ttlSecondsAfterFinished: 300
      template:
        spec:
          restartPolicy: Never
          containers:
            - name: warmer
              image: curlimages/curl:latest
              command:
                - /bin/sh
                - -c
                - |
                  for endpoint in /api/popular /api/categories /api/featured; do
                    STATUS=$(curl -s -o /dev/null -w "%{http_code}" "http://api-service:3000${endpoint}")
                    echo "Warmed ${endpoint}: HTTP ${STATUS}"
                  done