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02 Services & Networking

Goal

Expose the Patient Triage app to the internet using Kubernetes Services and an Ingress controller with path-based routing.

Estimated time

15 minutes.

Official references

Key concepts

Concept Purpose
ClusterIP Default Service type. Accessible only inside the cluster.
LoadBalancer Provisions an Azure Load Balancer with a public IP.
Ingress Layer-7 routing (host/path based) via a reverse proxy.
Ingress Controller The actual NGINX (or other) pod that fulfils Ingress rules.

Exercise

Step 1 — Enable the app-routing add-on

AKS provides a managed NGINX Ingress controller through the app-routing add-on:

az aks approuting enable \
  --resource-group $RESOURCE_GROUP \
  --name $AKS_CLUSTER_NAME

Verify the Ingress controller pods are running:

kubectl get pods -n app-routing-system

Step 2 — Understand the existing Services

In lesson 01 we created two ClusterIP Services. Review them:

kubectl get svc -n triage

Both are ClusterIP — accessible inside the cluster only.

Step 3 — Apply the Ingress resource

The Ingress routes external traffic to the correct backend:

  • /api/* → triage-backend:80
  • /* → triage-frontend:80
kubectl apply -f manifests/aks/ingress.yaml

Step 4 — Get the external IP

Wait for the Ingress to be assigned an external address:

kubectl get ingress -n triage --watch

Once the ADDRESS column shows an IP, press Ctrl+C and open it in a browser:

export INGRESS_IP=$(kubectl get ingress triage-ingress -n triage -o jsonpath='{.status.loadBalancer.ingress[0].ip}')
echo "Open http://$INGRESS_IP in your browser"

Step 5 — Test the routes

# Frontend — should return HTML
curl -s http://$INGRESS_IP/ | head -5

# Backend API — should return JSON
curl -s http://$INGRESS_IP/api/health

Step 6 — Test the triage flow

Open http://<INGRESS_IP> in your browser. Submit a patient with symptoms and confirm you see a triage result with an urgency classification.

What this lab demonstrates

  1. The difference between ClusterIP, LoadBalancer, and Ingress.
  2. Enabling the managed AKS app-routing NGINX Ingress controller.
  3. Path-based routing with a single external IP.
  4. End-to-end connectivity from browser → Ingress → Service → Pod.

Expected result

A single public IP that routes /api/* to the backend and everything else to the frontend. The Patient Triage UI loads in the browser and can submit patients.

Verification

  • [ ] kubectl get ingress -n triage shows an external IP.
  • [ ] curl http://$INGRESS_IP/api/health returns {"status": "healthy"}.
  • [ ] Opening the IP in a browser shows the Patient Triage UI.
  • [ ] Submitting a patient returns an urgency classification.