Jenkins – Complete Tutorial

1. What is Jenkins?

Jenkins is an open-source Continuous Integration and Continuous Delivery (CI/CD) automation server written in Java.

• Automates build, test, and deployment
• Integrates with Git, Maven, Selenium, Docker
• Plugin-based architecture
• Used in DevOps pipelines

2. What is CI & CD?

• Continuous Integration – Frequent code integration
• Continuous Testing – Automated test execution
• Continuous Deployment – Automated release

3. Installing Jenkins

• Requires Java (JDK 8+)
• Install on Windows / Linux / Mac
• Can run as WAR or Service

java -jar jenkins.war

4. Jenkins Dashboard & UI

• Dashboard
• New Item
• Build History
• Manage Jenkins
• Console Output

5. Jenkins Job Types

• Freestyle Project
• Pipeline Project
• Multibranch Pipeline
• Folder

6. Freestyle Job – Example

Simple job to execute Maven tests.

mvn clean test

7. Jenkins with Git & GitHub

• Source Code Management (SCM)
• GitHub credentials
• Webhook triggers

8. Jenkins with Maven

mvn clean install

• Compiles code
• Runs TestNG tests
• Generates artifacts

9. Jenkins with Selenium Automation

• Execute Selenium + TestNG suites
• Headless browser execution
• Parallel execution support

10. Jenkins Pipeline

Pipelines define CI/CD as code.

pipeline {
  agent any
  stages {
    stage('Build') {
      steps {
        sh 'mvn clean compile'
      }
    }
    stage('Test') {
      steps {
        sh 'mvn test'
      }
    }
  }
}

11. Declarative vs Scripted Pipeline

• Declarative – Simple & structured
• Scripted – More control & flexibility

12. Jenkins Agents (Slaves)

• Distributed builds
• Master-Agent architecture
• Node labels

13. Build Triggers

• SCM polling
• GitHub webhook
• Schedule (cron)
• Manual trigger

14. Jenkins Plugins

• Git Plugin
• Maven Integration
• TestNG Plugin
• Allure / Extent Reports
• Email Extension

15. Test Reports & Notifications

• HTML Reports
• TestNG Results
• Email Notifications
• Slack Integration

16. Jenkins Security

• User authentication
• Role-based access
• Credentials management

17. Real-Time CI/CD Flow

• Developer pushes code to Git
• Jenkins job triggered
• Build + Test executed
• Reports generated
• Deployment initiated

18. Interview Questions & Real-Time Usage

• Difference between CI & CD
• What is Jenkins Pipeline?
• How Jenkins executes Selenium tests?
• Freestyle vs Pipeline job
• Master-Agent architecture