A StatefulSet in Kubernetes is a workload API object designed to manage stateful applications. Unlike Deployments, which are used for stateless applications, StatefulSets are specifically tailored for applications that require stable, unique network identifiers, persistent storage, and ordered, graceful deployment and scaling.
Key Characteristics of StatefulSets:
Stable, Unique Network Identifiers: Each pod in a StatefulSet has a unique, persistent hostname and ID, which remains consistent across rescheduling and restarts. This is crucial for applications that need to maintain a stable network identity, such as databases and distributed systems[1][2][3].
Persistent Storage: StatefulSets ensure that each pod is associated with a persistent storage volume. This means that even if a pod is rescheduled to a different node, it retains access to its original data. This is achieved through PersistentVolumeClaims (PVCs) that are uniquely associated with each pod[1][3][5].
Ordered, Graceful Deployment and Scaling: StatefulSets manage the deployment and scaling of pods in a specific order. Pods are created, updated, and deleted in a sequential manner, ensuring that the application maintains its state and order. This is particularly important for applications that require a specific startup or shutdown sequence[3][4][5].
Automated Rolling Updates: StatefulSets support automated rolling updates, ensuring that updates are applied in a predictable order. This helps maintain application stability and consistency during updates[5].
Use Cases for StatefulSets:
StatefulSets are ideal for applications that require:
