Scaling Deployments in Kubernetes - Mini Project: Build & Apply

Scaling Deployments in Kubernetes

📖 Scenario: You are managing a web application running on Kubernetes. The application needs to handle more users during peak hours. To do this, you will learn how to scale the number of pods in a deployment.

🎯 Goal: Learn how to create a Kubernetes deployment and scale it up by increasing the number of pods.

📋 What You'll Learn

Create a deployment YAML file with a specific name and image

Add a replicas field to set the number of pods

Use kubectl commands to apply the deployment and scale it

Verify the number of pods running matches the desired count

💡 Why This Matters

🌍 Real World

Scaling deployments is essential to handle varying user loads in real applications. It helps maintain performance and availability.

💼 Career

Kubernetes deployment scaling is a fundamental skill for DevOps engineers and site reliability engineers managing cloud-native applications.

1

Create a Deployment YAML file

Create a file named deployment.yaml with a Kubernetes deployment named webapp using the image nginx:1.21. Set the initial number of replicas to 1. Include the required fields: apiVersion, kind, metadata, and spec with replicas and template containing containers with the image.

Kubernetes

# Write the deployment.yaml content here
# Your code here

Need a hint?

Remember to include replicas: 1 under spec and set the container image to nginx:1.21.

2

Apply the Deployment and Check Pods

Use the command kubectl apply -f deployment.yaml to create the deployment. Then use kubectl get pods -l app=webapp to list the pods with the label app=webapp. Write the exact commands below.

Kubernetes

apiVersion: apps/v1
kind: Deployment
metadata:
  name: webapp
spec:
  replicas: 1
  selector:
    matchLabels:
      app: webapp
  template:
    metadata:
      labels:
        app: webapp
    spec:
      containers:
      - name: nginx-container
        image: nginx:1.21

# Apply the deployment
# Your code here

# List pods with label app=webapp
# Your code here

Need a hint?

Use kubectl apply -f deployment.yaml to create the deployment and kubectl get pods -l app=webapp to see the pods.

3

Scale the Deployment to 3 Replicas

Update the deployment.yaml file to set replicas to 3. Then use the command kubectl apply -f deployment.yaml again to apply the change.

Kubernetes

apiVersion: apps/v1
kind: Deployment
metadata:
  name: webapp
spec:
  replicas: 3  # Change replicas to 3
  selector:
    matchLabels:
      app: webapp
  template:
    metadata:
      labels:
        app: webapp
    spec:
      containers:
      - name: nginx-container
        image: nginx:1.21

# Apply the updated deployment
# Your code here

Need a hint?

Change the replicas field to 3 and apply the deployment again.

4

Verify the Number of Pods Running

Run the command kubectl get pods -l app=webapp --no-headers | wc -l to count the number of pods running with label app=webapp. Then print the number using echo in the format: Pods running: 3.

Kubernetes

apiVersion: apps/v1
kind: Deployment
metadata:
  name: webapp
spec:
  replicas: 3
  selector:
    matchLabels:
      app: webapp
  template:
    metadata:
      labels:
        app: webapp
    spec:
      containers:
      - name: nginx-container
        image: nginx:1.21

kubectl apply -f deployment.yaml

# Count pods and print the result
# Your code here

Need a hint?

Use command substitution to count pods and then print with echo.