How does Deployment differ from StatefulSet?

Deployment and StatefulSet are controllers in Kubernetes for managing pods, but they serve different purposes.

Deployment is used for managing stateless applications. It provides:

• Scaling
• Rollout updates with rollback
• Replacement of failed pods

Pods created by Deployment are identical and do not have persistent state or unique identifiers.

StatefulSet is designed for stateful applications where preserving state and uniqueness are important:

• Each pod gets a stable, unique identifier (name)
• The order of creation, update, and deletion of pods is maintained
• Can be used with persistent volumes (PersistentVolumes) attached to specific pods

An example of using StatefulSet is databases, clusters where stability of identifiers and data is crucial.

Thus, the choice between Deployment and StatefulSet depends on whether the application needs to preserve state and have stable pod identifiers.