Capstone — Deploy Campus Library on Kubernetes

Time for the real thing. This challenge chains everything you learned into one small project. Plan for about one hour. If you get stuck, the answer to every step is already in the pages you've read.

Goal

By the end, you should have a multi-replica Campus Library app running on Kubernetes with a Service, ConfigMap, health checks, and the ability to scale and rollback.

Step 1 · The App

Create a simple Node.js app that reads from environment variables:

Create the project

mkdir campus-library-k8s
cd campus-library-k8s

k8s/configmap.yaml

cat > k8s/configmap.yaml << 'EOF'
apiVersion: v1
kind: ConfigMap
metadata:
  name: app-config
data:
  APP_NAME: "Campus Library"
  APP_PORT: "3000"
EOF

k8s/deployment.yaml

cat > k8s/deployment.yaml << 'EOF'
apiVersion: apps/v1
kind: Deployment
metadata:
  name: campus-library
spec:
  replicas: 3
  selector:
    matchLabels:
      app: campus-library
  template:
    metadata:
      labels:
        app: campus-library
    spec:
      containers:
        - name: web
          image: node:20-alpine
          command: ["node", "-e"]
          args:
            - |
              const http = require('http');
              const name = process.env.APP_NAME || 'Campus Library';
              const port = process.env.APP_PORT || 3000;
              const server = http.createServer((req, res) => {
                if (req.url === '/health') return res.writeHead(200).end('OK');
                res.writeHead(200, {'Content-Type': 'application/json'});
                res.end(JSON.stringify({app: name, status: 'running', hostname: require('os').hostname()}));
              });
              server.listen(port, () => console.log(name + ' on port ' + port));
          ports:
            - containerPort: 3000
          envFrom:
            - configMapRef:
                name: app-config
          livenessProbe:
            httpGet:
              path: /health
              port: 3000
            initialDelaySeconds: 5
            periodSeconds: 10
          readinessProbe:
            httpGet:
              path: /health
              port: 3000
            initialDelaySeconds: 3
            periodSeconds: 5
          resources:
            requests:
              memory: "64Mi"
              cpu: "100m"
            limits:
              memory: "128Mi"
              cpu: "250m"
EOF

k8s/service.yaml

cat > k8s/service.yaml << 'EOF'
apiVersion: v1
kind: Service
metadata:
  name: campus-library-svc
spec:
  selector:
    app: campus-library
  ports:
    - port: 80
      targetPort: 3000
  type: NodePort
EOF

Step 2 · Deploy

Apply everything

kubectl apply -f k8s/

configmap/app-config created
deployment.apps/campus-library created
service/campus-library-svc created

Verify Pods are running

kubectl get pods -l app=campus-library

NAME                            READY   STATUS    RESTARTS   AGE
campus-library-7d4b8c9f-x2k4m  1/1     Running   0          15s
campus-library-7d4b8c9f-a9n3p  1/1     Running   0          15s
campus-library-7d4b8c9f-q8w2r  1/1     Running   0          15s

Step 3 · Test

Test the app

curl $(minikube service campus-library-svc --url)

{"app":"Campus Library","status":"running","hostname":"campus-library-7d4b8c9f-x2k4m"}

The hostname changes on each request — traffic is load-balanced across all 3 Pods.

Step 4 · Scale

Scale to 5

kubectl scale deployment campus-library --replicas=5

Verify

kubectl get pods -l app=campus-library

NAME                            READY   STATUS    RESTARTS   AGE
campus-library-7d4b8c9f-x2k4m  1/1     Running   0          2m
campus-library-7d4b8c9f-a9n3p  1/1     Running   0          2m
campus-library-7d4b8c9f-q8w2r  1/1     Running   0          2m
campus-library-7d4b8c9f-m3j5n  1/1     Running   0          5s
campus-library-7d4b8c9f-k8p2w  1/1     Running   0          5s

Step 5 · Update and Rollback

Update the ConfigMap

kubectl create configmap app-config --from-literal=APP_NAME="Campus Library v2" --dry-run=client -o yaml | kubectl apply -f -

Restart to pick up the new config

kubectl rollout restart deployment/campus-library

Test the update

curl $(minikube service campus-library-svc --url)

{"app":"Campus Library v2","status":"running","hostname":"..."}

Rollback if needed

kubectl rollout undo deployment/campus-library

Step 6 · Cleanup

Delete everything

kubectl delete -f k8s/

Remember

This capstone chained: ConfigMap → Deployment → Service → health checks → scaling → rollout → rollback. This is exactly how production Kubernetes works.