🚀 Jenkins CI/CD + Docker for Java Web App

This is a sample project demonstrating CI/CD pipeline using Maven, Jenkins, Docker, and EKS.

Project Architecture

Objective:

1. Deploy your Java (Maven) web app from GitHub to an EC2 server using Jenkins and Docker. You’ll push code → Jenkins builds WAR → Docker builds image → Runs app.

This guide walks you through deploying a Java Web App using:

• ✅ Maven (to build)
• ✅ Docker (to containerize and run)
• ✅ Jenkins (to automate everything)
• ✅ EC2 (to host Jenkins)

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🧱 PART 1: Setup Jenkins EC2 Server

🔧 STEP 1: Launch EC2 in AWS

1. Go to AWS Console → EC2 → Launch Instance
2. Instance Name: jenkins-server
3. OS: Choose Ubuntu 20.04
4. Instance Type: t2.medium (2GB RAM minimum for Docker + Jenkins)
5. Key Pair: Create/download a new key pair (save .pem file)
6. Network Settings: o Open the ports below:
   • ✅ SSH (22)

• ✅ HTTP (80) - ✅ Custom TCP → Port 8080 (for Jenkins)

7. Click Launch Instance

➡️ Done? Copy the Public IPv4 address, you’ll need it.

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🖥️ STEP 2: Connect to EC2

ssh -i your-key.pem ubuntu@<your-ec2-ip>

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⚙️ STEP 3: Install Java, Maven, Git, Docker

sudo apt update -y
sudo apt install maven git -y
sudo apt install -y openjdk-17-jdk
java -version
mvn -v
git --version

✅ Install Docker:

# Update and install prerequisites
sudo apt update
sudo apt install \
    ca-certificates \
    curl \
    gnupg \
    lsb-release -y

# Add Docker's GPG key
sudo mkdir -p /etc/apt/keyrings
curl -fsSL https://download.docker.com/linux/ubuntu/gpg | \
  sudo gpg --dearmor -o /etc/apt/keyrings/docker.gpg

# Add Docker repo
echo \
  "deb [arch=$(dpkg --print-architecture) signed-by=/etc/apt/keyrings/docker.gpg] \
  https://download.docker.com/linux/ubuntu \
  $(lsb_release -cs) stable" | \
  sudo tee /etc/apt/sources.list.d/docker.list > /dev/null

# Update and install Docker
sudo apt update
sudo apt install docker-ce docker-ce-cli containerd.io docker-buildx-plugin docker-compose-plugin -y

# Enable and test Docker
sudo systemctl enable docker
sudo systemctl start docker
sudo docker run hello-world
sudo systemctl daemon-reexec
sudo systemctl daemon-reload
sudo systemctl restart docker
sudo systemctl status docker

🔄 If Docker Is Not Running

1. If it shows inactive or failed, you can try restarting and checking logs:

   sudo systemctl restart docker
   sudo journalctl -u docker --no-pager --lines=30
   

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🤖 STEP 4: Install Jenkins

sudo apt update
curl -fsSL https://pkg.jenkins.io/debian-stable/jenkins.io-2023.key | sudo tee /usr/share/keyrings/jenkins-keyring.asc > /dev/null
echo "deb [signed-by=/usr/share/keyrings/jenkins-keyring.asc] https://pkg.jenkins.io/debian-stable binary/" | sudo tee /etc/apt/sources.list.d/jenkins.list > /dev/null
sudo apt install jenkins -y
sudo systemctl start jenkins
sudo systemctl enable jenkins

sudo systemctl status jenkins

✅ Give Jenkins Docker access:

sudo usermod -aG docker jenkins
id jenkins


#Restart the instance (or logout and login again):
sudo reboot

✅ Open Jenkins in browser:

http://<your-ec2-ip>:8080

#Get the first-time password:

sudo cat /var/lib/jenkins/secrets/initialAdminPassword

• Paste password → Install Suggested Plugins → Create Admin

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🚚 PART 2: Prepare GitHub Repo

🗂️ Your Project Structure (✅ you already shared)

Make sure your GitHub project contains:

• Dockerfile (your final one)
• pom.xml (for main + webapp module)
• webapp/ folder (contains index.jsp, etc.)
• .gitignore (exclude target/)

🆙 Push Code to GitHub (if not already)

git init
git remote add origin https://github.com/<your-username>/<your-repo>.git
git add .
git commit -m "Initial commit"
git push -u origin main

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🛠️ PART 3: Create Jenkins CI/CD Pipeline

🔐 STEP 6: Add GitHub Credentials to Jenkins

1. Go to Jenkins → Manage Jenkins → Credentials → (Global) → Add Credentials
2. Choose:
   • Kind: Username & Password OR GitHub PAT
   • ID: github-creds

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⚙️ STEP 7: Create a Jenkins Pipeline Job

1. Go to Jenkins Dashboard → New Item
2. Name: java-webapp-cicd
3. Choose: Pipeline → Click OK

In the "Pipeline" section → choose “Pipeline Script” and paste this:

pipeline {
  agent any
  environment {
    IMAGE_NAME = 'java-webapp'
  }
  stages {
    stage('Clone') {
      steps {
        git credentialsId: 'github-creds', url: 'https://github.com/OphirCloud/maven-jenkins-cicd-docker-eks-project.git'
      }
    }
    stage('Maven Build') {
      steps {
        sh 'mvn clean install -pl webapp -am'
      }
    }
    stage('Build Docker Image') {
      steps {
        sh 'docker build -t $IMAGE_NAME .'
      }
    }
    stage('Run Container') {
      steps {
        sh '''
        docker rm -f java-webapp-container || true
        docker run -d -p 80:8080 --name java-webapp-container $IMAGE_NAME
        '''
      }
    }
  }
}

---

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🚀 PART 4: Run Your Jenkins Job

▶️ STEP 8: Start the Pipeline

1. Click Build Now
2. Console Output shows:
   • Git Clone ✅
   • Maven Build WAR ✅
   • Docker Image ✅
   • Docker Container ✅

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🌍 STEP 9: Open Web App

In browser:

http://<your-ec2-ip>

user:admin password: admin

🎉 You’ll see your index.jsp from the WAR file running inside Tomcat + Docker!

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📦 PART 5: Bonus Commands

# List containers
docker ps

# # All containers (including stopped)
docker ps -a 

# Stop container
docker stop java-webapp-container

# Remove container
docker rm java-webapp-container

# Remove image
docker rmi java-webapp

#🔁 Rebuild the Docker Image
docker build -t java-webapp .

#🚀 Run the Container (exposing port 8080)
docker run -d --name java-webapp-container -p 8080:8080 java-webapp

#📂 See Container Logs
docker logs java-webapp-container

# 📥 Copy Files From a Running Container
docker cp java-webapp-container:/opt/tomcat/webapps/webapp.war ./webapp.war

#🖥️ Access Container Shell
docker exec -it java-webapp-container bash

#💥 Force Remove All Stopped Containers and Dangling Images
docker container prune -f
docker image prune -f

#📋 List Docker Images

docker images

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📊 Architecture Diagram (Text View)

[GitHub] 
   |
   | (Push code)
   v
[Jenkins EC2 Server]
   |--> Maven Build WAR
   |--> Docker Build Image
   |--> Docker Run Container
   |
   v
[Your Web App] → http://<EC2-IP>

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✅ Diagram to Understand (Kid-style)

+---------------------+      GitHub Push       +---------------------+
|   Developer Laptop  |  ------------------->  |     GitHub Repo     |
+---------------------+                        +---------------------+
                                                    |
                                                    v
      +------------------------------------------------------------+
      | EC2 Ubuntu Server (Jenkins + Docker + Java + Maven)        |
      |                                                            |
      |  [ Jenkins Pipeline ]                                      |
      |   1. Clone Code from GitHub                                |
      |   2. Build WAR using Maven                                 |
      |   3. Build Docker image using Dockerfile                   |
      |   4. Run Container exposing port 80                        |
      +------------------------------------------------------------+
                                                    |
                                                    v
                                 Web App available at http://<EC2-IP>

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✅ What You Achieved

✅ Task	Done
EC2 created with right ports	✅
Jenkins installed and running	✅
Docker, Maven, Java setup	✅
Jenkins pipeline for your code	✅
WAR built and deployed inside Docker	✅
Web app live on EC2	✅

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🚀 PART 4: Build Artifacts Location (Workspace)

✅ 1. Build Artifacts Location (Workspace)

Every time Jenkins runs a job, it stores all the files in the workspace.

✅ Option A: GUI – Jenkins Dashboard

1. Go to your Jenkins job.
2. Click on the last successful build.
3. Click on "Workspace" (left sidebar).
4. You'll see:
   • Your project folder
   • Compiled files
   • target/ folder → Contains .war file:

     /var/lib/jenkins/workspace/java-webapp-cicd/target/webapp.war
     

✅ Option B: Jenkins Server (Linux Terminal)

cd /var/lib/jenkins/workspace/<your-job-name>/
ls -l

cd target/
ls -l
# webapp.war should be here

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✅ 2. If You Used archiveArtifacts in Pipeline

If your Jenkinsfile has:

archiveArtifacts artifacts: 'target/*.war', fingerprint: true

Then Jenkins archives the WAR file under:

Jenkins → Job → Build → "Archived Artifacts"

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✅ 3. If You Built Docker Image

1. If Jenkins builds a Docker image, the WAR gets copied into the Tomcat image in the Docker layer, but not stored locally on Jenkins after build (unless you keep a copy manually).

docker exec -it <container_id> bash
cd /opt/tomcat/webapps/
ls -l
# You’ll see: webapp.war and expanded webapp/

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✅ Summary

Case	Where to Look
Maven .war build	/var/lib/jenkins/workspace/<job>/target/webapp.war
GUI – Workspace	Jenkins → Job → Build → Workspace
Archived Artifacts	Jenkins → Job → Build → Archived Artifacts
Docker container WAR file	/opt/tomcat/webapps/ inside container

---

💣 Project Destroy Option (When You Don't Need It Anymore)

✅ Updated Jenkinsfile with Destroy Option

pipeline {
  agent any
  environment {
    IMAGE_NAME = 'java-webapp'
    CONTAINER_NAME = 'java-webapp-container'
  }
	
  parameters {
    booleanParam(name: 'DESTROY', defaultValue: false, description: 'Check this if you want to destroy everything (container, image, workspace)')
  }

  stages {
    stage('Clone') {
      when { expression { !params.DESTROY } }
      steps {
        git credentialsId: 'github-creds', url: 'https://github.com/OphirCloud/maven-jenkins-cicd-docker-eks-project.git'
      }
    }

    stage('Maven Build') {
      when { expression { !params.DESTROY } }
      steps {
        sh 'mvn clean install -pl webapp -am'
      }
    }

    stage('Build Docker Image') {
      when { expression { !params.DESTROY } }
      steps {
        sh 'docker build -t $IMAGE_NAME .'
      }
    }

    stage('Run Container') {
      when { expression { !params.DESTROY } }
      steps {
        sh '''
          docker rm -f $CONTAINER_NAME || true
          docker run -d -p 80:8080 --name $CONTAINER_NAME $IMAGE_NAME
        '''
      }
    }

    stage('Destroy Everything') {
      when { expression { params.DESTROY } }
      steps {
        echo "🧨 Destroying container, image, and cleaning workspace..."

        sh '''
          echo "Stopping and removing container..."
          docker rm -f $CONTAINER_NAME || true

          echo "Removing Docker image..."
          docker rmi -f $IMAGE_NAME || true

          echo "Cleaning Jenkins workspace..."
          rm -rf * || true
        '''
      }
    }
  }

  post {
    always {
      echo "✅ Pipeline completed."
    }
  }
}

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✅ How to Use It

1. Click “Build with Parameters”
2. ✅ Tick the checkbox “DESTROY”
3. 💥 The pipeline will:
   • Stop and remove the container
   • Remove the image
   • Clean the workspace

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🔥 Output Example (when DESTROY is checked)

🧨 Destroying container, image, and cleaning workspace...
Stopping and removing container...
Removing Docker image...
Cleaning Jenkins workspace...

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