When to use scripted over declarative in Jenkins - Mini Project: Build & Apply

When to Use Scripted Over Declarative in Jenkins Pipelines

📖 Scenario: You are a DevOps engineer working on automating software builds and deployments using Jenkins. Jenkins supports two main ways to write pipelines: scripted and declarative. Understanding when to use scripted pipelines instead of declarative ones helps you handle complex automation tasks effectively.

🎯 Goal: Learn to create a simple Jenkins scripted pipeline that includes a conditional step, showing when scripted pipelines are preferred over declarative pipelines.

📋 What You'll Learn

Create a Jenkins scripted pipeline with a map of build stages

Add a configuration variable to control which stages run

Use a for loop to iterate over stages and run selected ones

Print the names of the stages that are executed

💡 Why This Matters

🌍 Real World

Jenkins pipelines automate software build, test, and deployment tasks. Scripted pipelines are used when automation needs complex logic beyond simple linear steps.

💼 Career

DevOps engineers and automation specialists use scripted pipelines to create flexible CI/CD workflows that adapt to changing project requirements.

1

Create a map of build stages

Create a variable called buildStages as a map with these exact entries: 'Build': 'Compile code', 'Test': 'Run unit tests', 'Deploy': 'Deploy to staging'

Jenkins

# Create the buildStages map with exact entries
# Your code here

Need a hint?

Use Groovy map syntax with keys and values inside square brackets.

2

Add a configuration variable to select stages

Create a variable called stagesToRun as a list containing the exact strings 'Build' and 'Test'

Jenkins

def buildStages = ['Build': 'Compile code', 'Test': 'Run unit tests', 'Deploy': 'Deploy to staging']
# Create stagesToRun list with 'Build' and 'Test'
# Your code here

Need a hint?

Use Groovy list syntax with square brackets and comma-separated strings.

3

Use a for loop to run selected stages

Write a for loop with variable stageName to iterate over buildStages.keySet(). Inside the loop, use an if statement to check if stageName is in stagesToRun. If yes, print "Running stage: " + stageName

Jenkins

def buildStages = ['Build': 'Compile code', 'Test': 'Run unit tests', 'Deploy': 'Deploy to staging']
def stagesToRun = ['Build', 'Test']
# Use for loop to iterate buildStages.keySet() and print running stages
# Your code here

Need a hint?

Use Groovy for loop and contains() method on list.

4

Print the executed stages

Add a print statement that outputs exactly "Running stage: Build" and "Running stage: Test" when the script runs

Jenkins

def buildStages = ['Build': 'Compile code', 'Test': 'Run unit tests', 'Deploy': 'Deploy to staging']
def stagesToRun = ['Build', 'Test']
for (stageName in buildStages.keySet()) {
    if (stagesToRun.contains(stageName)) {
        println("Running stage: " + stageName)
    }
}
# Run the script to see output

Need a hint?

Run the script and check the console output matches the expected lines.