🚀 Chattingo – DevOps Deployment Guide

Project: Chattingo – Real-time Chat App (React + Spring Boot)

Owner: Tanvir Mulla

This repo contains a complete CI/CD deployment plan using Jenkins, Docker, DockerHub, and Hostinger VPS, with atomic blue/green-style release swap and automatic rollback.

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🎯 Quick Summary

Image Tagging: YYYYmmddHHMM- → readable & deterministic

Atomic Release Swap: Deploys to /opt/chattingo/releases/ → swaps current → previous if health fails

Frontend Fingerprinting: Injects BUILD_ID into index.html to prevent cache issues

Health-Gated Rollback: Automatic rollback if http://YOUR_VPS_IP:8080/actuator/health fails within 60s

Minimal Downtime: Users always see a working site during deployment

Reproducible: Scripts, Dockerfiles, docker-compose, Jenkinsfile included

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✅ Prerequisites

Before deployment, ensure you have the following:

Placeholder	Description
YOUR_DOCKERHUB_USER	DockerHub username
YOUR_VPS_IP	Hostinger VPS IP
SSH_USER	VPS SSH username (root/ubuntu)
GIT_BRANCH	Git branch to deploy (e.g., devops-implementation)
Jenkins Credentials	DockerHub username/password + VPS SSH private key (vps-ssh)

🏗 File Structure Overview

chattingo/

frontend/

├─ Dockerfile

└─ nginx.frontend.conf

├─ backend/

├─ Dockerfile

└─ src/...

├─ jenkins/

└─ Jenkinsfile

├─ docker-compose.yml

├─ .env.template

└─ README.md

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📅 4-Day Deployment

Day 1 – VPS Environment Setup & Verification 🖥️

Objective: Prepare VPS for Docker + Nginx deployment.

Task	Commands / Notes
SSH into VPS	ssh SSH_USER@YOUR_VPS_IP
Update system	sudo apt update && sudo apt upgrade -y
Install Docker & Compose	sudo apt install -y docker-ce docker-ce-cli containerd.io docker-compose-plugin sudo usermod -aG docker $(whoami)
Install Nginx & Git	sudo apt install -y nginx git
Test Docker	docker run hello-world
Create release dirs	sudo mkdir -p /opt/chattingo/releases /opt/chattingo/current /opt/chattingo/previous

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Deliverable: VPS ready, Docker/Nginx installed, directories created. ✅

Day 2 – Dockerize App & Local Deployment 🐳

Objective: Build frontend/backend images & run locally.

Task	Description / Commands
Backend Dockerfile	Multi-stage Gradle → JRE build (backend/Dockerfile)
Frontend Dockerfile	Inject BUILD_ID in index.html (frontend/Dockerfile)
Docker Compose	Connect frontend + backend + MySQL (docker-compose.yml)
Run containers	docker compose up -d --build
Test API	curl -X POST http://localhost:8081/api/login -H "Content-Type: application/json" -d '{"username":"testuser","password":"testpass"}'

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Deliverable: Application running on VPS IP (http://72.60.111.20) ✅

Day 3 – CI/CD with Jenkins 🔧

Objective: Automate build, scan, push, and deploy.

Task	Commands / Notes
Install Jenkins	sudo apt install jenkins
Configure Jenkins creds	DockerHub + VPS SSH key (vps-ssh)
Create Jenkinsfile	Stages: Checkout → Build → Scan → Push → Deploy
Configure pipeline	Branch: devops-implementation
Test pipeline	Push commit → Jenkins auto-build & deploy
Deploy Script	/usr/local/bin/deploy_release.sh – atomic swap + rollback

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Deliverable: Jenkins automates Docker image build and deployment. ✅

Day 4 – Application Testing & Monitoring 🔍

Objective: Ensure the app is fully functional and monitored.

Task	Commands / Notes
Verify login/signup	Access frontend → test APIs via React UI
Database check	docker exec -it <db_container> mysql -uroot -p → verify tables & data
Container check	docker ps and docker compose logs -f

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Deliverable: Application fully tested

⚠️ Common Problems & Solutions

Problem	Cause	Solution
Backend exits immediately	DB not ready	Use Docker depends_on or wait-for-db script
Frontend cannot reach backend	Nginx proxy points to wrong port/service	Update nginx.frontend.conf to correct backend port/service name
API returns connection error	Docker network not configured	Ensure all services are on same Docker network (bridge)
Docker build fails	Missing dependencies	Verify Dockerfile COPY paths & Gradle/npm installed
Cache issues	Frontend assets cached in browser	Use __BUILD_ID__ placeholder → replaced in Dockerfile for cache busting
Jenkins cannot SSH	Wrong credentials	Add correct SSH private key in Jenkins credentials (vps-ssh)

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🛠️ Troubleshooting Quick Commands

Command	Purpose
sudo docker ps	List running containers
sudo docker compose logs -f	View logs
sudo docker compose up -d --build --remove-orphans	Rebuild containers
docker network ls	Verify Docker networks
docker exec -it <container> bash	Access container for debug

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