Lefty – Surplus Food Marketplace

A platform connecting users with restaurants to rescue surplus food at discounted prices, reducing food waste while saving money.

🚀 How to Run

Prerequisites

• Docker & Docker Compose
• Node.js 18+ (for local development)
• MySQL 8.0+
• Redis (optional, for performance optimization)

Docker Setup (Recommended)

# Navigate to project root
cd /Users/nihaocheng/Desktop/Sideproject/Lefty

# Start all services (Docker, Nginx, MySQL, Node.js)
docker compose up -d --build

# Services will be available at:
# - Frontend: http://localhost:8081
# - Backend API: http://localhost:3000
# - Nginx Proxy: http://localhost:80
# - MySQL: localhost:3306

Service Architecture

nginx (Port 80/443)
  ├── Frontend (Port 8081)
  ├── Backend API (Port 3000)
  │   ├── Node.js Server x3 (Load Balanced)
  │   ├── MySQL Database
  │   └── Redis Cache
  └── Health Checks

Local Development (Without Docker)

# Backend
cd backend
npm install
npm run dev

# Frontend
cd lefty-app
npm install
npm start

Stop Services

docker compose down

# Clean up volumes
docker compose down -v

---

📊 Redis Performance Testing

Test Environment: 5,000 merchants / 25,000 meal boxes / 20km search radius

Range(km)	Records	No Cache(ms)	First Cache(ms)	Cache Hit(ms)	Speedup
3.0	200	262.0	549.0	168.0	1.56x
5.0	200	325.7	405.0	65.0	5.01x
10.0	200	374.3	536.0	70.0	5.35x
15.0	200	421.3	535.0	61.0	6.91x
20.0	200	535.0	777.0	66.0	8.11x

Key Findings:

• 🚀 Larger search radius = Better Redis advantage (1.56x → 8.11x)
• ⚡ 20km range: MySQL takes 535ms, Redis only 66ms
• 📈 Search range impact: Performance gap increases significantly with distance
• 💾 Cache stability: Hit time consistent at 61-168ms

Best Performance: 20km range with 8.11x speedup

---

🖼️ AWS S3 Image Storage

Overview

• Frontend uploads images directly to AWS S3 bucket
• Backend stores S3 image URLs in MySQL database
• Database retrieves and displays images via stored URLs

Flow

Frontend (Image Upload)
    ↓
AWS S3 (Image Storage)
    ↓
Backend API (Store S3 URL)
    ↓
MySQL Database (URL Storage)
    ↓
Frontend Display (Load from URL)

Database Schema

CREATE TABLE mealbox (
  id INT PRIMARY KEY AUTO_INCREMENT,
  merchant_id INT NOT NULL,
  name VARCHAR(255) NOT NULL,
  description TEXT,
  img_url VARCHAR(500),  -- S3 URL stored here
  original_price DECIMAL(10, 2),
  discount_price DECIMAL(10, 2),
  quantity INT,
  pickup_time_start TIME,
  pickup_time_end TIME,
  created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
  FOREIGN KEY (merchant_id) REFERENCES merchant(id)
);

Example URL

https://lefty-mealbox-images.s3.ap-southeast-2.amazonaws.com/merchants/123/mealboxes/0/1733600123456-abc123.jpg

---

🔄 GitHub CI/CD

Automated Workflows

┌─ GitHub Push
└─ Trigger Actions
   ├─ Run Tests (Jest/Mocha)
   ├─ Lint Code (ESLint)
   ├─ Build Docker Image
   ├─ Push to Registry
   └─ Deploy to Production (Render/Vercel)

Current Setup

• Backend Testing: Automated on every push to master
• Build Pipeline: Docker image building & optimization
• Deployment Targets:
  • Backend: Render
  • Frontend: Vercel

Workflow Files

Located in .github/workflows/:

• test.yml - Run tests and lint
• build.yml - Build Docker images
• deploy.yml - Deploy to production

View CI/CD Status

• Backend:
• Check Actions tab: https://github.com/NicksonCheng/Lefty_backend/actions

---

📚 Project Structure

Lefty/
├── backend/                 # Express.js API Server
│   ├── src/
│   │   ├── server.ts       # Main entry point
│   │   ├── db.ts           # Database connection
│   │   ├── routes/         # API endpoints
│   │   ├── services/       # Business logic
│   │   ├── repositories/   # Database queries
│   │   └── middleware/     # Auth, validation, etc.
│   ├── tests/              # Test files
│   └── Dockerfile
├── lefty-app/              # Expo React Native Frontend
│   ├── src/
│   │   ├── screens/        # Screen components
│   │   ├── services/       # S3 upload service
│   │   ├── api/            # API client
│   │   └── contexts/       # Auth context
│   └── app.json            # Expo config
├── nginx/                  # Nginx proxy config
├── mysql-init/             # Database initialization
├── docker-compose.yml      # Multi-container orchestration
└── README.md

🔗 Related Repositories

• Frontend (Expo React Native)
• Backend API (Express.js)

📝 License

MIT License - See LICENSE file for details