What is Kubernetes StatefulSet advanced patterns?

Advanced StatefulSet patterns for managing stateful applications: 1. Init containers for initialization: clone data, wait for leader, create configuration: initContainers: - name: clone-data image: gcr.io/google-samples/xtrabackup:1.0 command: ["/bin/bash", "-c", "nohup mysqldump --all-databases > /backup/all-databases.sql &"] volumeMounts: - name: data mountPath: /backup. 2. Sidecar containers for replication: xtrabackup sidecar alongside MySQL — handles backup/restore without modifying main container. 3. Pod Management Policy: podManagementPolicy: Parallel — create all pods simultaneously (default: OrderedReady — sequential). Use Parallel for bootstrapping replicas. 4. Update strategy OnDelete: updateStrategy: type: OnDelete — pods only updated when manually deleted. Fine-grained control over database rolling upgrades. 5. Headless service + DNS: each pod addressable at pod-{N}.service.namespace.svc.cluster.local. Configure application to use specific pod DNS for primary (pod-0) vs replicas. 6. VolumeClaimTemplates with StorageClass: each pod gets its own PVC automatically created by StatefulSet. PVCs are NOT deleted when pod is scaled down — data preserved for pod return. Manually delete PVCs if data should be removed. 7. Ordinal-based configuration: MY_POD_INDEX=$(echo $MY_POD_NAME | grep -o "[0-9]*$") — extract ordinal from pod name. Configure pod-0 as primary, others as replicas. 8. Stable network identity for cluster formation: ZooKeeper, Kafka, Cassandra use stable DNS names for initial cluster formation — critical that pod-0.my-service resolves consistently. 9. Graceful scale-down: StatefulSet stops highest-ordinal pod first. Application should drain connections before terminating (preStop hook, gracefulShutdown). 10. CloudNativePG operator: production-grade PostgreSQL on Kubernetes — manages HA primary/replica, automated failover, backup to S3, monitoring — better than bare StatefulSet for databases.