StatefulSet
StatefulSet is a Kubernetes workload API object used to manage stateful applications, such as databases or message queues, that require stable network identities, persistent storage, and ordered deployment and scaling. It ensures that each pod in the set has a unique, persistent identifier and maintains its state across pod rescheduling or restarts. This is in contrast to stateless deployments like Deployments, which treat pods as interchangeable instances.
Developers should use StatefulSets when deploying applications that need stable, unique network hostnames (e.g., for service discovery), persistent storage volumes that survive pod restarts, and ordered, graceful deployment and scaling (e.g., for master-slave database setups). Common use cases include running distributed databases like MongoDB or Cassandra, message brokers like Kafka, and other clustered services where pod identity and data persistence are critical for consistency and reliability.