Running PostgreSQL on AKS with Premium SSD (StatefulSet + Azure Managed Disk)

In this tutorial, we’ll deploy PostgreSQL on AKS using:

• StatefulSet
• Azure Managed Disk (CSI)
• ReadWriteOnce (RWO)
• Premium SSD storage
• Persistent volume validation

On Azure Kubernetes Service

---

🧠 Why Run PostgreSQL on AKS?

Common use cases:

• SaaS apps with per-tenant DB
• Internal microservice database
• Dev/Test ephemeral environments
• Platform engineering demos

Key benefits:

✅ Data survives pod restarts
✅ Azure-managed disk durability
✅ Zone-aware scheduling
✅ Snapshot + backup integration

---

🏗 Architecture Overview

PostgreSQL runs as:

• StatefulSet
• Backed by Azure Managed Disk
• Using CSI driver
• Access mode: ReadWriteOnce
• Storage SKU: Premium_LRS

Kubernetes dynamically provisions the disk.

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Step 1️⃣ — Verify StorageClass

AKS automatically creates a default CSI storage class.

Check it:

kubectl get storageclass

Then inspect:

kubectl describe storageclass default

Look for:

Provisioner: disk.csi.azure.com
skuName: Premium_LRS

If you see Premium_LRS, you're using Premium SSD.

---

Step 2️⃣ — Create Namespace

kubectl create namespace postgres-demo

---

Step 3️⃣ — Create Secret

apiVersion: v1
kind: Secret
metadata:
  name: postgres-secret
  namespace: postgres-demo
type: Opaque
stringData:
  POSTGRES_PASSWORD: supersecurepassword

Apply:

kubectl apply -f secret.yaml

---

Step 4️⃣ — Create Headless Service

StatefulSets require a headless service.

apiVersion: v1
kind: Service
metadata:
  name: postgres
  namespace: postgres-demo
spec:
  clusterIP: None
  selector:
    app: postgres
  ports:
    - port: 5432

Apply:

kubectl apply -f service.yaml

---

Step 5️⃣ — Deploy PostgreSQL StatefulSet

⚠ Important: Azure disks contain a lost+found directory at root.

PostgreSQL refuses to initialize if the directory is not empty.

We fix this by using a subdirectory via PGDATA.

apiVersion: apps/v1
kind: StatefulSet
metadata:
  name: postgres
  namespace: postgres-demo
spec:
  serviceName: postgres
  replicas: 1
  selector:
    matchLabels:
      app: postgres
  template:
    metadata:
      labels:
        app: postgres
    spec:
      containers:
      - name: postgres
        image: postgres:15
        ports:
        - containerPort: 5432
        env:
        - name: POSTGRES_PASSWORD
          valueFrom:
            secretKeyRef:
              name: postgres-secret
              key: POSTGRES_PASSWORD
        - name: PGDATA
          value: /var/lib/postgresql/data/pgdata
        volumeMounts:
        - name: postgres-data
          mountPath: /var/lib/postgresql/data
  volumeClaimTemplates:
  - metadata:
      name: postgres-data
    spec:
      accessModes: ["ReadWriteOnce"]
      storageClassName: default
      resources:
        requests:
          storage: 10Gi

Apply:

kubectl apply -f statefulset.yaml

---

Step 6️⃣ — Verify Deployment

Wait for pod:

kubectl rollout status statefulset/postgres -n postgres-demo

Check PVC:

kubectl get pvc -n postgres-demo

Check pod:

kubectl get pods -n postgres-demo

You should see:

postgres-0   Running

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Step 7️⃣ — Confirm Azure Disk Creation

In Azure Portal:

1. Open resource group starting with:

   MC_<your-rg>_<cluster>_<region>

1. Find the Managed Disk
2. Verify:

• SKU = Premium SSD
• Size = 10Gi
• Attached to AKS node

AKS automatically:

• Created disk
• Attached it
• Mounted it
• Bound PVC to Pod

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Step 8️⃣ — Test Persistence

Enter PostgreSQL:

kubectl exec -it postgres-0 -n postgres-demo -- psql -U postgres

Create database:

CREATE DATABASE demo;

Now delete pod:

kubectl delete pod postgres-0 -n postgres-demo

Wait for restart:

kubectl rollout status statefulset/postgres -n postgres-demo

Verify:

kubectl exec -it postgres-0 -n postgres-demo -- psql -U postgres -l

You should still see:

demo

✅ Data persisted
✅ Disk reattached automatically
✅ No data loss

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🔍 What This Demonstrates

Feature	Why It Matters
StatefulSet	Stable volume binding
RWO	Single-writer DB safety
Azure CSI	Dynamic disk provisioning
Premium SSD	Low latency production storage
PGDATA fix	Proper Azure disk compatibility

---

🏆 Production Improvements

For real workloads, add:

• Resource limits
• Liveness/readiness probes
• PodDisruptionBudget
• Anti-affinity rules
• Replica for HA
• Backup strategy (Velero or Azure Backup)
• Monitoring (Azure Monitor / Prometheus)

---

🎯 Final Architecture

PostgreSQL (StatefulSet)
↓
PVC (RWO)
↓
Azure Managed Disk (Premium SSD)
↓
Zone-aware AKS node

---

🚀 When to Use This Pattern

Use PostgreSQL on AKS if:

• You need full control
• You want per-tenant DB isolation
• You want environment parity (dev → prod)
• You’re building platform-level tooling

Use managed DB service instead if:

• You want automatic patching
• You want built-in HA
• You don’t want operational overhead

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🔚 Conclusion

You’ve now:

✔ Deployed PostgreSQL on AKS
✔ Used Azure Premium SSD
✔ Configured StatefulSet properly
✔ Solved lost+found issue
✔ Verified data persistence

This is the foundation of running stateful workloads on AKS safely and correctly.