Simple Kubernetes App

Deploy a basic nginx application using plain Kubernetes manifests.

Time: ~5 minutes Difficulty: Beginner

What You Will Learn

• Creating a Deployment with replicas
• Exposing pods with a Service
• Resource requests and limits
• Inspecting running workloads

Deploy

Navigate to the demo directory:

cd demos/simple-app

Then apply the manifests:

kubectl apply -f manifests/namespace.yaml
kubectl apply -f manifests/

Verify

# Check pods are running
kubectl get pods -n simple-app

# Check the service
kubectl get svc -n simple-app

# Access the app
kubectl port-forward svc/simple-nginx-service 8080:80 -n simple-app

Open http://localhost:8080 in your browser. You should see the default nginx welcome page.

What is Happening

manifests/
  deployment.yaml   # 2 replicas of nginx:1.25.3-alpine
  service.yaml      # ClusterIP service on port 80

The Deployment creates 2 pods running nginx with resource limits (50m CPU, 64Mi memory). The Service provides a stable internal endpoint so other components can reach nginx without knowing which pod handles the request.

Experiment

1. Scale the deployment:

   kubectl scale deployment simple-nginx --replicas=4 -n simple-app

2. Watch pods come up:

   kubectl get pods -n simple-app -w

3. Delete a pod and watch it get recreated:

   kubectl delete pod -l app=simple-nginx -n simple-app --wait=false
   kubectl get pods -n simple-app -w

Cleanup

kubectl delete namespace simple-app

Further Reading

See docs/deep-dive.md for a deeper look at how Deployments use ReplicaSets, why Services exist, how labels connect everything, and what happens when you misconfigure resource limits.

Next Step

Move on to Helm to learn how templating makes manifests reusable.