How does Deployment differ from StatefulSet?

Deployment and StatefulSet are two types of controllers in Kubernetes that manage pod deployment but serve different purposes.

Deployment is used for managing stateless applications. It ensures the creation and updating of pods, guaranteeing the desired number of replicas. Pods in a Deployment are interchangeable and do not have a persistent state.

StatefulSet is designed for stateful applications where a stable pod identity, startup order, and data persistence are important. StatefulSet provides unique pod names and stable storage (PersistentVolume), which is crucial for databases and other stateful services.

Example:

• Deployment — web servers that can scale and restart without data loss.
• StatefulSet — databases, cache systems, where each instance must have a persistent identifier and storage.