Blue-green deployment pattern in Jenkins - Mini Project: Build & Apply

Blue-green deployment pattern

📖 Scenario: You work as a DevOps engineer managing a web application deployment. To avoid downtime during updates, you want to use the blue-green deployment pattern. This means you have two identical environments: blue and green. Only one environment serves live traffic at a time. When deploying a new version, you update the inactive environment, then switch traffic to it.

🎯 Goal: Build a Jenkins pipeline script that defines two environments blue and green, sets the active environment, deploys the new version to the inactive environment, and switches traffic to it.

📋 What You'll Learn

Create a variable environments with values ['blue', 'green']

Create a variable activeEnv set to 'blue'

Write a function getInactiveEnv that returns the environment not currently active

Print the inactive environment, deploy to it, then switch activeEnv to it

Print the new active environment after switching

💡 Why This Matters

🌍 Real World

Blue-green deployment is used in real companies to update applications without downtime by switching traffic between two identical environments.

💼 Career

Understanding this pattern helps DevOps engineers automate safe deployments and reduce risks during updates.

1

Define environments list

Create a variable called environments and set it to the list ['blue', 'green'].

Jenkins

# Create a variable called environments with ['blue', 'green']
environments = ['blue', 'green']

Need a hint?

Use square brackets to create a list with two strings: 'blue' and 'green'.

2

Set active environment

Create a variable called activeEnv and set it to the string 'blue'.

Jenkins

environments = ['blue', 'green']
# Set activeEnv to 'blue'
activeEnv = 'blue'

Need a hint?

Assign the string 'blue' to the variable activeEnv.

3

Create function to get inactive environment

Write a function called getInactiveEnv that returns the environment from environments that is not equal to activeEnv. Use a for loop with variable env to check each environment.

Jenkins

environments = ['blue', 'green']
activeEnv = 'blue'

# Define getInactiveEnv function

def getInactiveEnv():
    # Your code here

Need a hint?

Loop over environments and return the one not equal to activeEnv.

4

Deploy to inactive environment and switch active environment

Call getInactiveEnv() and store the result in inactiveEnv. Print "Deploying to {inactiveEnv} environment". Then set activeEnv to inactiveEnv. Finally, print "Switched active environment to {activeEnv}".

Jenkins

environments = ['blue', 'green']
activeEnv = 'blue'

def getInactiveEnv():
    for env in environments:
        if env != activeEnv:
            return env

# Deploy and switch active environment
inactiveEnv = getInactiveEnv()
# Your code here

Need a hint?

Use print statements with string formatting to show deployment and switching messages.