🧱 Three-Tier MERN Application

This is a full-stack three-tier web application built with:

• Frontend: React + Nginx
• Backend: Node.js + Express
• Database: MongoDB Atlas (Cloud DB)

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📁 Folder Structure

.

• ├── backend/ # Express.js backend API
• ├── frontend/ # React frontend (served via Nginx)
• ├── docker-compose.yml # Docker Compose configuration file
• └── README.md # Project documentation

📥 Step 1: Clone the Repository

• Fork the repository

 git clone https://github.com/<your-username>/<your-repo>.git 

• cd your-repo

MongoDB Atlas

1️⃣ Create a MongoDB Atlas Account

• Go to: https://www.mongodb.com/cloud/atlas
• Sign up (Google/GitHub/Email)
• After login, click "Build a Database"

2️⃣ Create Free Cluster

• Choose “Shared” Tier (Free) → Click "Create"
• Cloud Provider & Region: Choose AWS or GCP (select a nearby region)
• Cluster Name: e.g., three-tier-cluster
• Click Create Cluster (takes ~1-2 minutes)

4️⃣ Add IP Whitelist

• Go to "Network Access"
• Click “Add IP Address”
• Choose ALLOW ACCESS FROM ANYWHERE (0.0.0.0/0) for now
• You can restrict to your EC2 IP for production

5️⃣ Get the Connection String

• Go to Clusters > Connect > Connect your application
• Choose driver: Node.js, version >= 3.6
• Copy the URI:

 MONGO_URI="mongodb+srv://<username>:<password>@cluster0.mongodb.net/three-tier-db?retryWrites=true&w=majority" 

-

Replace with your actual password.

6️⃣ Add Environment Variables

• Create a .env file inside the backend/ folder:

backend/.env

MONGO_URI="mongodb+srv://<username>:<password>@cluster0.mongodb.net/three-tier-db?retryWrites=true&w=majority" 

7️⃣ Run the Application

Backend

cd backend
node server.js

Frontend

cd frontend
npm start