Cluster upgrade strategies in Kubernetes - Mini Project: Build & Apply

Deployment Upgrade Strategies

📖 Scenario: You are a DevOps engineer managing a Kubernetes cluster for a small company. The cluster runs several applications, and you need to upgrade the applications safely without downtime.This project will guide you through defining and simulating different application upgrade strategies using Kubernetes concepts.

🎯 Goal: Build a simple Kubernetes manifest and commands to simulate application upgrade strategies: blue-green and canary. You will create deployment configurations and update them step-by-step to understand how upgrades can be done safely.

📋 What You'll Learn

Create a Kubernetes deployment manifest with a specific version label

Add a configuration variable to select upgrade strategy

Implement the upgrade logic using kubectl commands and manifest changes

Output the final deployment status to verify upgrade success

💡 Why This Matters

🌍 Real World

Application upgrade strategies help keep applications running smoothly while updating software versions without downtime.

💼 Career

Understanding upgrade strategies is essential for DevOps engineers to maintain high availability and reliability in production Kubernetes clusters.

1

Create initial deployment manifest

Create a Kubernetes deployment manifest named app-deployment.yaml with these exact specifications: deployment name myapp, container image myapp:v1, and 3 replicas.

Kubernetes

# Write the deployment manifest with name 'myapp', image 'myapp:v1', and replicas 3
# Your code here

Need a hint?

Use apiVersion: apps/v1 and kind: Deployment. Set replicas to 3 and label the pods with version: v1.

2

Add upgrade strategy variable

Create a variable named upgrade_strategy and set it to the string blue-green to select the upgrade method.

Kubernetes

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

# Define upgrade strategy variable
# Your code here

Need a hint?

Use a simple assignment statement in Python style to set upgrade_strategy to "blue-green".

3

Implement blue-green upgrade logic

Write a command to simulate the blue-green upgrade by creating a new deployment named myapp-green with image myapp:v2 and 3 replicas. Use the same labels but set version: v2 for the new deployment.

Kubernetes

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

upgrade_strategy = "blue-green"

# Simulate blue-green upgrade by defining new deployment manifest for 'myapp-green' with image 'myapp:v2'
# Your code here

Need a hint?

Copy the deployment manifest structure and change metadata.name to myapp-green, image to myapp:v2, and label version to v2.

4

Output deployment status

Write a command to print the status of both deployments myapp and myapp-green using kubectl get deployments myapp myapp-green.

Kubernetes

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

upgrade_strategy = "blue-green"

# New deployment manifest for blue-green upgrade
apiVersion: apps/v1
kind: Deployment
metadata:
  name: myapp-green
spec:
  replicas: 3
  selector:
    matchLabels:
      app: myapp
      version: v2
  template:
    metadata:
      labels:
        app: myapp
        version: v2
    spec:
      containers:
      - name: myapp-container
        image: myapp:v2

# Print deployment status
# Your code here

Need a hint?

Use a print statement to show the exact command kubectl get deployments myapp myapp-green.