Java Web App CI/CD Pipeline on AWS

(GitHub → Jenkins → Ansible → Docker → Kubernetes)

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Overview

This project demonstrates a complete end-to-end CI/CD pipeline for a Java-based web application using leading DevOps tools — from source code to deployment on a live Kubernetes cluster.

It integrates GitHub, Jenkins, Ansible, Docker, Docker Hub, and Kubernetes (EKS) to automate the entire build, deployment, and release process.

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Architecture Workflow

Developer → GitHub → Jenkins → Ansible → Docker → Docker Hub → Kubernetes (EKS) → AWS LoadBalancer → User

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Tools and Technologies Used

Tool / Service	Purpose
GitHub	Source Code Management (SCM) and webhook trigger
Jenkins	CI/CD orchestration and pipeline automation
Maven	Build automation tool for packaging Java WAR
Docker	Containerization of the application
Docker Hub	Central registry for storing Docker images
Ansible	Automates Docker build and Kubernetes deployment
Kubernetes (EKS)	Container orchestration and scaling
Tomcat	Java web server runtime for WAR
AWS EC2	Hosts Jenkins, Docker, Ansible, and K8s nodes
AWS LoadBalancer	Exposes the application publicly

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Pipeline Workflow

1️⃣ Developer Stage

• Developer commits and pushes code to the main branch in GitHub.
• A GitHub Webhook triggers Jenkins automatically on every commit.

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2️⃣ Jenkins CI Stage

• Jenkins pulls the latest code from GitHub.
• Jenkins connects to the Ansible server via SSH.
• Ansible runs playbook_docker.yml to:
  • Build the Docker image using the project’s Dockerfile.
  • Tag and push it to Docker Hub (aa309m/myapp:latest).

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3️⃣ Jenkins CD Stage

• Jenkins triggers another Ansible playbook k8s_deploy.yml.
• This deploys the latest image to Kubernetes (EKS) using:
  • deployment.yml (for Pods)
  • service.yml (for LoadBalancer)

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4️⃣ Kubernetes Stage

• Kubernetes pulls the latest image from Docker Hub.
• Pods and Services are created.
• AWS ELB exposes the application publicly.

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5️⃣ Verification Stage

• Jenkins verifies deployment via:

  kubectl get pods
  kubectl get svc
  curl http://<load-balancer-dns>/myapp/HelloServlet
  

Expected Output:

Hello from HelloServlet! {"id": "1111", "name": "Up1"}

Folder Structure

my-java-web-app/
│
├── Dockerfile
├── Jenkinsfile
├── pom.xml
│
├── src/
│   ├── main/java/api/servlet/HelloServlet.java
│   └── main/webapp/WEB-INF/web.xml
│
├── ansible/
│   ├── playbook_docker.yml
│   ├── k8s_deploy.yml
│
├── k8s/
│   ├── deployment.yaml
│   └── service.yaml
│
└── README.md

Key Jenkinsfile Stages

pipeline {
    agent any
    stages {

        stage('Build & Push Docker Image') {
            steps {
                echo 'Building Docker image and pushing to DockerHub...'
                sshagent(['ansible_ssh']) {
                    sh '''
                        ssh -o StrictHostKeyChecking=no ec2-user@<ansible-server-ip> "
                        ansible-playbook ~/playbook_docker.yml
                        "
                    '''
                }
            }
        }

        stage('Deploy to Kubernetes') {
            steps {
                echo 'Deploying to Kubernetes...'
                sshagent(['ansible_ssh']) {
                    sh '''
                        ssh -o StrictHostKeyChecking=no ec2-user@<ansible-server-ip> "
                        ansible-playbook ~/k8s_deploy.yml
                        "
                    '''
                }
            }
        }

        stage('Post-Deployment Check') {
            steps {
                echo 'Verifying deployed application...'
                sshagent(['ansible_ssh']) {
                    sh '''
                        ssh -o StrictHostKeyChecking=no ec2-user@<k8s-server-ip> "
                        kubectl get svc
                        "
                    '''
                }
            }
        }
    }
}

🧩 Common Commands Used

Purpose	Command
Build WAR file	mvn clean package -DskipTests
Build Docker image	docker build -t aa309m/myapp:latest .
Push to Docker Hub	docker push aa309m/myapp:latest
Get pods	kubectl get pods -o wide
Get services	kubectl get svc
Scale pods	kubectl scale deployment myapp-deployment --replicas=2
Restart deployment	kubectl rollout restart deployment myapp-deployment
Test endpoint	curl http://<load-balancer-dns>/myapp/HelloServlet

Sample Output

$ kubectl get pods NAME READY STATUS RESTARTS AGE myapp-deployment-xxxx 1/1 Running 0 2m myapp-deployment-yyyy 1/1 Running 0 2m

$ curl http:///myapp/HelloServlet Hello from HelloServlet! {"id": "1111", "name": "Up1"}

Key Learnings

✅ Built and automated a multi-server CI/CD pipeline from scratch
✅ Configured GitHub Webhook → Jenkins Trigger for automatic builds
✅ Implemented Ansible automation for Docker & Kubernetes deployment
✅ Debugged real-world issues (EC2 IP changes, credential fixes, etc.)
✅ Connected Jenkins → Ansible → EKS for full infrastructure delivery

Result

Fully automated CI/CD pipeline

End-to-end integration: GitHub → Jenkins → Ansible → Docker → Kubernetes

Real-time build triggers via GitHub Webhooks

Application deployed & verified via AWS LoadBalancer