Explain Kubernetes StatefulSets and when to use them over Deployments.

StatefulSets manage stateful applications that require stable network identities, persistent storage, and ordered deployment/scaling.\n\nStatefulSet Characteristics:\n• Stable, unique network identifiers\n• Stable, persistent storage\n• Ordered, graceful deployment and scaling\n• Ordered, automated rolling updates\n\nKey Differences from Deployments:\n• Pods have stable names (app-0, app-1, app-2)\n• Each pod gets its own PersistentVolume\n• Pods are created/deleted in order\n• Network identity persists across restarts\n\nUse Cases:\n• Databases (MySQL, PostgreSQL, MongoDB)\n• Distributed systems (Kafka, Elasticsearch)\n• Applications requiring stable storage\n• Leader election scenarios\n\nExample StatefulSet:\napiVersion: apps/v1\nkind: StatefulSet\nmetadata:\n name: mysql\nspec:\n serviceName: mysql\n replicas: 3\n selector:\n matchLabels:\n app: mysql\n template:\n metadata:\n labels:\n app: mysql\n spec:\n containers:\n - name: mysql\n image: mysql:8.0\n ports:\n - containerPort: 3306\n volumeMounts:\n - name: data\n mountPath: /var/lib/mysql\n volumeClaimTemplates:\n - metadata:\n name: data\n spec:\n accessModes: ["ReadWriteOnce"]\n resources:\n requests:\n storage: 10Gi\n\nBest Practices:\n• Use headless services for StatefulSets\n• Implement proper backup strategies\n• Configure pod disruption budgets\n• Use init containers for setup tasks\n• Monitor storage usage and performance