This repository contains a minimal Java application designed to demonstrate a complete CI/CD workflow using Jenkins, Maven, Docker, and Docker Compose.

This project is intended for beginners who want to learn:

• How to create a simple Java application
• How to build, compile, and test it using Maven
• How to containerize it with Docker
• How to run it using Docker Compose
• How to automate the entire workflow using a Jenkins pipeline

The application itself is a simple Java "Hello World" program with a basic JUnit test.

java-jenkins-docker/
│── src/
│   ├── main/java/com/example/App.java         # Main Java Application
│   └── test/java/com/example/AppTest.java     # Unit Tests (JUnit)
│── pom.xml                                    # Maven Build File
│── Dockerfile                                 # Docker Image Definition
│── docker-compose.yml                         # Docker Compose Configuration
│── Jenkinsfile                                # Jenkins Pipeline Script
│── README.md                                  # Project Documentation

We use Maven to compile the Java source code:

mvn clean package

• mvn clean removes any previous build artifacts.
• mvn package compiles the code and packages it into a JAR file.
• Output JAR: target/java-jenkins-docker-1.0-SNAPSHOT.jar

The project includes a basic JUnit test:

mvn test

This runs all tests inside the src/test/java directory.

Maven automatically compiles the Java source files during the package phase:

mvn compile

This ensures all Java files are translated into .class files in the target/classes directory.

After building the project, run the application locally:

java -jar target/java-jenkins-docker-1.0-SNAPSHOT.jar

Expected Output:

Hello from Java Application for Jenkins CI/CD!

docker build -t java-jenkins-docker:latest .

docker run --rm java-jenkins-docker:latest

If you want to run the app using Docker Compose:

docker-compose up --build

docker-compose down

The provided Jenkinsfile automates the process:

pipeline {
    agent any
    stages {
        stage('Build') {
            steps {
                sh 'mvn clean package'
            }
        }
        stage('Test') {
            steps {
                sh 'mvn test'
            }
        }
        stage('Docker Build') {
            steps {
                sh 'docker build -t java-jenkins-docker:latest .'
            }
        }
        stage('Docker Run') {
            steps {
                sh 'docker run --rm java-jenkins-docker:latest'
            }
        }        
    }
}

Pipeline Stages:

1. Build – Compiles and packages the Java code
2. Test – Runs JUnit tests
3. Docker Build & Run – Builds and runs the Docker image

You need to have the following installed:

• Java 17+
• Apache Maven
• Docker
• Docker Compose
• Jenkins (optional for CI/CD testing)

This project is released under the MIT License.