Horizontal Pod Autoscaler in Kubernetes - Mini Project: Build & Apply

Horizontal Pod Autoscaler

📖 Scenario: You manage a web application running on Kubernetes. To handle varying user traffic, you want to automatically adjust the number of pods based on CPU usage.

🎯 Goal: Learn how to create a Horizontal Pod Autoscaler (HPA) in Kubernetes that scales the number of pods of a deployment based on CPU usage.

📋 What You'll Learn

Create a deployment named webapp with 2 replicas

Add resource requests for CPU in the deployment

Create a Horizontal Pod Autoscaler targeting the webapp deployment

Set the CPU utilization target to 50%

Verify the HPA configuration

💡 Why This Matters

🌍 Real World

Horizontal Pod Autoscaler helps keep applications responsive by automatically adjusting the number of pods based on CPU load, just like how a car adjusts speed based on traffic.

💼 Career

Understanding HPA is essential for Kubernetes administrators and DevOps engineers to ensure applications scale efficiently and cost-effectively.

1

Create a deployment named webapp with 2 replicas

Write a Kubernetes deployment YAML named webapp-deployment.yaml that creates a deployment called webapp with 2 replicas running the image nginx. Include container port 80.

Kubernetes

# Write the deployment YAML with name 'webapp', 2 replicas, image 'nginx', and container port 80
# Your code here

Need a hint?

Use kind: Deployment, set replicas: 2, and specify image: nginx with port 80.

2

Add CPU resource requests to the deployment

In the webapp-deployment.yaml, add CPU resource requests of 100m under resources.requests.cpu for the container named nginx.

Kubernetes

apiVersion: apps/v1
kind: Deployment
metadata:
  name: webapp
spec:
  replicas: 2
  selector:
    matchLabels:
      app: webapp
  template:
    metadata:
      labels:
        app: webapp
    spec:
      containers:
      - name: nginx
        image: nginx
        ports:
        - containerPort: 80
        # Add CPU resource requests of 100m below
        # Your code here

Need a hint?

Under the container, add resources: then requests: with cpu: 100m.

3

Create a Horizontal Pod Autoscaler targeting the webapp deployment

Write a YAML file named webapp-hpa.yaml that creates a Horizontal Pod Autoscaler targeting the deployment webapp. Set the minimum replicas to 2, maximum replicas to 5, and target average CPU utilization to 50%.

Kubernetes

apiVersion: apps/v1
kind: Deployment
metadata:
  name: webapp
spec:
  replicas: 2
  selector:
    matchLabels:
      app: webapp
  template:
    metadata:
      labels:
        app: webapp
    spec:
      containers:
      - name: nginx
        image: nginx
        ports:
        - containerPort: 80
        resources:
          requests:
            cpu: 100m

# Write the Horizontal Pod Autoscaler YAML below
# Your code here

Need a hint?

Use kind: HorizontalPodAutoscaler, set scaleTargetRef to deployment webapp, and set CPU target to 50%.

4

Display the Horizontal Pod Autoscaler status

Write the exact command to display the status of the Horizontal Pod Autoscaler named webapp-hpa in the default namespace.

Kubernetes

apiVersion: apps/v1
kind: Deployment
metadata:
  name: webapp
spec:
  replicas: 2
  selector:
    matchLabels:
      app: webapp
  template:
    metadata:
      labels:
        app: webapp
    spec:
      containers:
      - name: nginx
        image: nginx
        ports:
        - containerPort: 80
        resources:
          requests:
            cpu: 100m
---
apiVersion: autoscaling/v2
kind: HorizontalPodAutoscaler
metadata:
  name: webapp-hpa
spec:
  scaleTargetRef:
    apiVersion: apps/v1
    kind: Deployment
    name: webapp
  minReplicas: 2
  maxReplicas: 5
  metrics:
  - type: Resource
    resource:
      name: cpu
      target:
        type: Utilization
        averageUtilization: 50

# Write the kubectl command to show the HPA status
# Your code here

Need a hint?

Use kubectl get hpa webapp-hpa to see the autoscaler status.