PostgreSQL with Persistent Storage¶

RHEL 9 PostgreSQL 16

This example deploys PostgreSQL from the UBI-based registry.redhat.io/rhel9/postgresql-16 image with a PersistentVolumeClaim (PVC). It validates that the CSI driver and StorageClass work end-to-end: stateful workloads, persistent storage, and data that survives pod restarts.

Note

Distroless hardened images do not include a shell or psql client, so oc rsh into those images fails. This POC uses the UBI image so you can run the interactive checks below.

Prerequisites¶

Storage configured with a default StorageClass

Deploy PostgreSQL¶

Create a namespace:
```
oc new-project postgresql-demo
```

Create the PersistentVolumeClaim:

apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: postgresql-data
  namespace: postgresql-demo
spec:
  accessModes:
    - ReadWriteOnce
  resources:
    requests:
      storage: 10Gi

oc apply -f postgresql-pvc.yaml

Create the Deployment:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: postgresql
  namespace: postgresql-demo
  labels:
    app: postgresql
spec:
  replicas: 1
  selector:
    matchLabels:
      app: postgresql
  strategy:
    type: Recreate
  template:
    metadata:
      labels:
        app: postgresql
    spec:
      containers:
        - name: postgresql
          image: registry.redhat.io/rhel9/postgresql-16
          ports:
            - containerPort: 5432
          env:
            - name: POSTGRESQL_USER
              value: demo
            - name: POSTGRESQL_PASSWORD
              value: demo123
            - name: POSTGRESQL_DATABASE
              value: sampledb
          resources:
            requests:
              memory: "256Mi"
              cpu: "250m"
            limits:
              memory: "512Mi"
              cpu: "500m"
          volumeMounts:
            - name: postgresql-data
              mountPath: /var/lib/pgsql/data
          readinessProbe:
            tcpSocket:
              port: 5432
            initialDelaySeconds: 5
            periodSeconds: 10
          livenessProbe:
            tcpSocket:
              port: 5432
            initialDelaySeconds: 30
            periodSeconds: 10
      volumes:
        - name: postgresql-data
          persistentVolumeClaim:
            claimName: postgresql-data

oc apply -f postgresql-deployment.yaml

Create the Service:

oc expose deployment postgresql --port=5432

Verify the PVC is bound and the pod is running:

oc get pvc -n postgresql-demo
oc get pods -n postgresql-demo

Write Test Data¶

Connect to PostgreSQL and insert some data:

oc rsh deployment/postgresql

Inside the pod:

psql -U demo -d sampledb
CREATE TABLE demo (id serial PRIMARY KEY, message text, created_at timestamp DEFAULT now());
INSERT INTO demo (message) VALUES ('Hello from OpenShift!');
INSERT INTO demo (message) VALUES ('Persistent storage works.');
SELECT * FROM demo;
\q
exit

Test Persistence¶

Delete the pod (the Deployment will recreate it):

oc delete pod -l app=postgresql -n postgresql-demo

Wait for the new pod to start:
```
oc get pods -n postgresql-demo -w
```
Verify the data survived the pod restart:
```
oc rsh deployment/postgresql
```
```
psql -U demo -d sampledb
SELECT * FROM demo;
\q
exit
```
The rows inserted earlier should still be there, proving the PVC retained the data across pod recreation.

What to Show in a Demo¶

PVC binding — oc get pvc shows the claim bound to a PV provisioned by the CSI driver
Data persistence — data survives pod deletion and recreation
Storage class in action — the default StorageClass dynamically provisions the volume
Pod scheduling — the pod is scheduled to a node where the volume is accessible
Stateful workloads — OpenShift handles the same database workloads as traditional VMs

Cleanup¶

oc delete project postgresql-demo