9.8: NodePort Service for PVC-Backed Apps

https://drive.google.com/file/d/1Ga-gnT2z7j17YMyyRHL_8qb0t3XJdNa-/view?usp=sharing

🔍 YAML Breakdown

apiVersion: v1
kind: Service
meta
  name: website-svc
spec:
  type: NodePort          # ← Exposes on ALL node IPs
  selector:
    app: nginx            # ← Must match Deployment labels
  ports:
    - port: 80            # ← Service port (internal)
      targetPort: 80      # ← Pod port (where app listens)
      nodePort: 30007     # ← Fixed external port (30000-32767)

🔑 Key Insight:

This Service creates a stable external endpoint:

Internal: http://website-svc:80 (from inside cluster)

External: http://<ANY-k3s-NODE-IP>:30007 (from your laptop, browser, etc.)

💡 Why nodePort: 30007?

Fixed port = easier firewall rules, documentation, and testing

Without it, k3s assigns a random port in 30000-32767

📌 How It Works with Your PVC-Backed App

Component	Role
Deployment (`webapp`)	Runs 1 Pod with `app: nginx` label + PVC-mounted `/var/www/html`
Service (`website-svc`)	Routes traffic to that Pod via `selector: app: nginx`
PVC (`myclaim`)	Persists web content across Pod restarts
NodePort	Exposes the app externally on `:30007`

🎯 End-to-End Flow:

curl http://<NODE-IP>:30007

→ NodePort (30007)

→ Service (website-svc:80)

→ Pod (webapp-xxxx:80)

→ Persistent content from NFS/PV

🧪 k3s Lab: Test End-to-End Persistence + External Access

🔧 Step 1: Ensure All Components Are Deployed

# 1. PVC (from earlier)
kubectl get pvc myclaim

# 2. Deployment (with PVC)
kubectl apply -f deployment-using-pvc.yaml

# 3. Service
kubectl apply -f service-node-port.yaml

🔧 Step 2: Write Persistent Content

# Get Pod name
POD=$(kubectl get pods -l app=nginx -o jsonpath='{.items[0].metadata.name}')

# Write file
kubectl exec $POD -- sh -c "echo '<h1>Hello from Persistent NFS!</h1>' > /var/www/html/index.html"

🔧 Step 3: Test External Access

💡 Get k3s node IP(s):

kubectl get nodes -o wide
# NAME         INTERNAL-IP
# k3s-master   192.168.1.10
# k3s-node1    192.168.1.11

🌐 From your laptop:

curl <http://192.168.1.10:30007>
# ✅ "Hello from Persistent NFS!"

curl <http://192.168.1.11:30007>
# ✅ Same response! (kube-proxy forwards to Pod anywhere in cluster)