Pull request builds in Jenkins - Commands & Configuration

Introduction

When developers create a pull request, it is important to automatically test the changes before merging. Pull request builds run tests on the new code to catch errors early and keep the main project stable.

When you want to check if new code changes break the build before merging them.

When multiple developers work on the same project and you want to ensure quality.

When you want to automate testing for every pull request to save manual effort.

When you want to prevent broken code from entering the main branch.

When you want to provide feedback to developers quickly about their code changes.

Config File - Jenkinsfile

Jenkinsfile

pipeline {
  agent any
  triggers {
    githubPullRequest()
  }
  stages {
    stage('Build') {
      steps {
        echo 'Building the project...'
        // Add build commands here
      }
    }
    stage('Test') {
      steps {
        echo 'Running tests...'
        // Add test commands here
      }
    }
  }
}

This Jenkinsfile defines a pipeline that runs on any available agent.

The triggers section uses githubPullRequest() to start the build automatically when a pull request is created or updated.

There are two stages: Build and Test. Each stage runs commands to build and test the code changes.

Commands

This command updates or creates the Jenkins job that will run pull request builds based on the job configuration file.

Terminal

jenkins-jobs --conf jenkins.ini update my-pull-request-job.yaml

Expected Output

Job 'my-pull-request-job' updated successfully.

This command triggers the pull request build manually using a token for authentication.

Terminal

curl -X POST http://jenkins.example.com/job/my-pull-request-job/build?token=pr-build-token

Expected Output

Started build #15

This command fetches the console output of build number 15 to check the build and test results.

Terminal

jenkins-cli -s http://jenkins.example.com console my-pull-request-job 15

Expected Output

[Pipeline] Start of Pipeline

[Pipeline] echo

Building the project...

[Pipeline] echo

Running tests...

[Pipeline] End of Pipeline

Finished: SUCCESS

Key Concept

If you remember nothing else from this pattern, remember: pull request builds automatically test code changes before merging to keep the main project stable.

Common Mistakes

Not setting up the trigger for pull request events in Jenkins.

Without the trigger, builds won't start automatically when a pull request is created or updated.

Add the appropriate trigger like githubPullRequest() in the Jenkinsfile or configure webhook triggers in Jenkins.

Forgetting to add test steps in the pipeline stages.

If tests are not run, errors in the new code can go unnoticed and break the main branch.

Include test commands in the Test stage to verify code correctness.

Triggering builds without authentication tokens when required.

Build triggers may fail if Jenkins requires tokens or credentials for security.

Use the correct token or authentication method when triggering builds via API.

Summary

Create a Jenkins pipeline with triggers to run on pull request events.

Use stages to build and test the code changes automatically.

Trigger and monitor builds to ensure code quality before merging.