StatefulSet
A Kubernetes object that manages stateful applications by maintaining stable, persistent identities and storage for each pod replica, unlike Deployments which treat pods as interchangeable.
A StatefulSet is a Kubernetes workload resource designed for applications that require stable network identities, persistent storage, and ordered deployment. Each pod in a StatefulSet gets a unique, sticky hostname (e.g., mysql-0, mysql-1) that persists across restarts, unlike Deployments where pod names are random.
StatefulSets are essential for stateful applications like databases, message queues, and distributed systems that need consistent identity and storage. For example, a MySQL cluster deployed as a StatefulSet ensures that mysql-0 always uses the same PersistentVolume, maintaining data integrity across pod restarts and scaling operations.
Key features include ordered pod creation/deletion, headless services for direct pod access, and automatic management of PersistentVolumeClaims. Scaling and updates happen sequentially rather than in parallel, giving applications control over state consistency.