#Lab: Kubernetes Horizontal Pod Autoscaling

Automatically scale applications based on resource usage.

#🎯 Objectives

Configure Horizontal Pod Autoscaler (HPA)
Test autoscaling with load
Monitor scaling events

#📋 Prerequisites

Kubernetes cluster with metrics-server
kubectl configured

#⏱️ Duration: 30 minutes

#Task 1: Install Metrics Server (5 min)

bash

1# Check if metrics-server is running
2kubectl get pods -n kube-system | grep metrics
3
4# If not installed (minikube)
5minikube addons enable metrics-server
6
7# Or install manually
8kubectl apply -f https://github.com/kubernetes-sigs/metrics-server/releases/latest/download/components.yaml
9
10# Verify metrics work
11kubectl top nodes
12kubectl top pods -A

#Task 2: Deploy Test Application (5 min)

diagram

cat << 'EOF' | kubectl apply -f -
apiVersion: apps/v1
kind: Deployment
metadata:
  name: php-apache
spec:
  replicas: 1
  selector:
    matchLabels:
      app: php-apache
  template:
    metadata:
      labels:
        app: php-apache
    spec:
      containers:
      - name: php-apache
        image: registry.k8s.io/hpa-example
        ports:
        - containerPort: 80
        resources:
          requests:
            cpu: 200m
          limits:
            cpu: 500m
---
apiVersion: v1
kind: Service
metadata:
  name: php-apache
spec:
  selector:
    app: php-apache
  ports:
  - port: 80
EOF

# Verify deployment
kubectl get pods
kubectl get svc php-apache

#Task 3: Create HPA (5 min)

bash

1# Create HPA via command
2kubectl autoscale deployment php-apache \
3  --cpu-percent=50 \
4  --min=1 \
5  --max=10
6
7# Or via manifest
8cat << 'EOF' | kubectl apply -f -
9apiVersion: autoscaling/v2
10kind: HorizontalPodAutoscaler
11metadata:
12  name: php-apache
13spec:
14  scaleTargetRef:
15    apiVersion: apps/v1
16    kind: Deployment
17    name: php-apache
18  minReplicas: 1
19  maxReplicas: 10
20  metrics:
21  - type: Resource
22    resource:
23      name: cpu
24      target:
25        type: Utilization
26        averageUtilization: 50
27EOF
28
29# Check HPA status
30kubectl get hpa

#Task 4: Generate Load (10 min)

Open a new terminal and run:

bash

# Watch HPA scaling
kubectl get hpa php-apache --watch

In another terminal, generate load:

bash

1# Generate load
2kubectl run load-generator --rm -i --tty \
3  --image=busybox \
4  --restart=Never \
5  -- /bin/sh -c "while true; do wget -q -O- http://php-apache; done"

Watch the HPA terminal - pods should scale up as CPU increases.

#Task 5: Observe Scaling (5 min)

bash

1# Stop load generator (Ctrl+C)
2
3# Watch scale down (takes a few minutes)
4kubectl get hpa php-apache --watch
5
6# Check events
7kubectl describe hpa php-apache
8
9# View pods
10kubectl get pods -l app=php-apache

#✅ Success Criteria

Metrics server running
HPA created and targeting deployment
Pods scaled up under load
Pods scaled down when load removed

#🧹 Cleanup

bash

kubectl delete hpa php-apache
kubectl delete deployment php-apache
kubectl delete service php-apache