Persistent Storage

apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: postgres-data
spec:
  accessModes: [ReadWriteOnce]
  storageClassName: standard      # or gp3, pd-balanced, etc.
  resources:
    requests:
      storage: 20Gi
---
apiVersion: apps/v1
kind: StatefulSet                  # not Deployment for stateful workloads
metadata:
  name: postgres
spec:
  serviceName: postgres
  replicas: 1
  selector:
    matchLabels: { app: postgres }
  template:
    metadata: { labels: { app: postgres } }
    spec:
      containers:
        - name: postgres
          image: postgres:16-alpine
          env:
            - name: POSTGRES_PASSWORD
              valueFrom:
                secretKeyRef: { name: postgres-secret, key: password }
          ports:
            - containerPort: 5432
          volumeMounts:
            - mountPath: /var/lib/postgresql/data
              name: data
      volumes:
        - name: data
          persistentVolumeClaim:
            claimName: postgres-data