Pull request builds in Jenkins - Mini Project: Build & Apply

Pull Request Builds with Jenkins

📖 Scenario: You work on a software project where developers submit code changes through pull requests on GitHub. To keep the project stable, you want Jenkins to automatically build and test each pull request before merging.

🎯 Goal: Set up a Jenkins pipeline that triggers a build whenever a pull request is created or updated on GitHub. This helps catch errors early and ensures code quality.

📋 What You'll Learn

Create a Jenkinsfile with a pipeline definition

Configure the pipeline to trigger on pull request events

Add a simple build stage that prints the pull request ID

Print a confirmation message when the build runs

💡 Why This Matters

🌍 Real World

Many teams use Jenkins to automatically build and test code changes submitted via pull requests to catch errors early and maintain code quality.

💼 Career

Understanding pull request builds is essential for DevOps engineers to automate CI/CD pipelines and improve collaboration between developers.

1

Create Jenkinsfile with pipeline block

Create a Jenkinsfile with a pipeline block that defines the pipeline structure.

Jenkins

pipeline {
    // Your code here
}

Need a hint?

The Jenkinsfile must start with the pipeline keyword followed by curly braces.

2

Add triggers for pull request events

Inside the pipeline block, add a triggers section with githubPullRequest() to trigger builds on pull request events.

Jenkins

pipeline {
    triggers {
        // Your code here
    }
}

Need a hint?

Use the triggers block and add githubPullRequest() inside it.

3

Add a build stage to print pull request ID

Inside the pipeline block, add a stages section with one stage named Build. In the steps, add a script block that prints the pull request ID using env.CHANGE_ID.

Jenkins

pipeline {
    triggers {
        githubPullRequest()
    }
    stages {
        stage('Build') {
            steps {
                script {
                    // Your code here
                }
            }
        }
    }
}

Need a hint?

Use echo inside a script block to print the pull request ID from env.CHANGE_ID.

4

Print confirmation message when build runs

Add a post section inside the pipeline block with a always block that prints Build completed for pull request ${env.CHANGE_ID}.

Jenkins

pipeline {
    triggers {
        githubPullRequest()
    }
    stages {
        stage('Build') {
            steps {
                script {
                    echo "Building pull request ID: ${env.CHANGE_ID}"
                }
            }
        }
    }
    post {
        always {
            // Your code here
        }
    }
}

Need a hint?

The post block runs after the pipeline. Use always to print the confirmation message.