Difference between Kubernetes Deployments and StatefulSets

Deployments

Deployments manage stateless applications. Pods created by a Deployment are interchangeable, share the same PersistentVolumeClaim templates, and can be scaled horizontally without identity concerns. Use Deployments for web servers, APIs, and microservices.

apiVersion: apps/v1
kind: Deployment
metadata:
  name: web
spec:
  replicas: 3
  selector:
    matchLabels:
      app: web

StatefulSets

StatefulSets manage stateful applications that require stable network identity and persistent storage per Pod. Each Pod gets a unique, ordinal hostname and its own PersistentVolume.

apiVersion: apps/v1
kind: StatefulSet
metadata:
  name: db
spec:
  serviceName: db-headless
  replicas: 3

Choosing Between Them

Use Deployments for anything that does not care which Pod handles a request. Use StatefulSets for databases, message queues, and clustered stateful services. For monitoring these workloads, see how to set up Kubernetes monitoring with Prometheus. For zero-downtime updates, read how to implement zero-downtime deployments in Kubernetes.