StatefulSets and Persistent Volumes — Stable Identity for Stateful Workloads

Day 5 through Day 16 ran one stateless webapp Pod. Stateful workloads — Postgres, Kafka, anything with a disk it cares about — break that model entirely: Pods can't be interchangeable, names can't be random, storage can't disappear when a Pod restarts. StatefulSet is the workload type built for it. Deploy PostgreSQL behind a Headless Service with volumeClaimTemplates, write a row, delete the Pod, and watch the same Pod name come back with the same row already there.