🛒 E-commerce Checkout System (Microservices POC)

This repository contains the Cart + Auth Service implementation for the E-commerce Checkout System Challenge.
It demonstrates how to break down a monolithic checkout process into microservices, focusing on authentication, cart management, and integration with a product catalog (via an external FakeStore API).

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1. Architectural Proposal (Microservices View)

Services (High Level)

API Gateway / BFF

• Purpose: Single entry point for the frontend. Handles routing, rate-limiting, security headers, and proxies requests to services and third-party APIs.
• Responsibilities:
  • Proxy requests to Cart Service (/api/cart, /api/auth).
  • Proxy product data from FakeStore API (/api/products).
• Data: No persistent data; only configuration and runtime logs.

Auth Service (implemented inside Cart Service)

• Purpose: Handle user registration, login, JWT issuance, and user profiles.
• Data: User records (username, email, hashed password, role, timestamps).

Cart Service (this repo)

• Purpose: Manage users’ carts. (POC includes add-to-cart and get-cart endpoints).
• Data: Cart items (userId, productId, title, category, description, price, image, quantity).

Product Catalog

• Purpose: Canonical product data (pricing, images, stock).
• POC: Uses FakeStore API proxied through the gateway.

Order / Payment Service (Future Work)

• Purpose: Checkout flow, payment capture, order creation, stock reservation.

Why This Split?

• ✅ Separation of concerns → Auth, cart, payments, and catalog evolve independently.
• ✅ Independent scaling → Cart vs payment have different load patterns.
• ✅ Frontend simplicity → Gateway acts as a BFF (Backend-for-Frontend).

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2. Architecture Diagram

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3. How to Run Locally (Backend)

Prerequisites

• Node.js 18+ (or recent LTS)
• npm
• MongoDB (local or Atlas)

Cart Service Setup

# Clone the repo
git clone https://github.com/Favourof/bankend-microservice-ecormmrce.git
cd cart-service

# Install dependencies
npm install

# Create .env file
PORT=4001
MONGO_URI=mongodb://127.0.0.1:27017/cart-service
JWT_SECRET=yudrdvy6ygfe468378rt3rwdvscfdt3fcedriscudsjdcsatdcfjsvdsjfjvcjcvoqwjdncdihdgcvgdhewdfjewdgvewdfsdvsfcwtyefcdew

# Run the service
npm run dev

API Gateway Setup

cd api-gateway npm install

.env file

PORT=4000 CART_SERVICE_URL=http://localhost:4001 FAKESTORE_API_URL=https://fakestoreapi.com FRONTEND_URL=http://localhost:3000

Run

npm run dev

API Endpoints

#Auth

Method	Endpoint	Description
POST	/api/auth/register	Register a new user
POST	/api/auth/login	Login and get JWT token
GET	/api/auth/onAuthStateChanged	Get logged-in user (requires token)

Frontend (Next.js)

Clone frontend repo

git clone https://github.com/Favourof/frontend-microservice-ecormmrce.git cd ecommerce-frontend

Install deps

npm install

.env.local

NEXT_PUBLIC_API_URL=http://localhost:4000

Run frontend

npm run dev

Flow

/products → fetch product list from /api/products (proxied to FakeStore API).

"Add to Cart" → calls /api/cart/add-to-cart (requires login).

/cart → protected route, fetches cart items via /api/cart/get-cart/:userId.