Microservices FastAPI Demo

A demonstration of microservices architecture using FastAPI and Redis for inter-service communication.

This project implements a simple e-commerce flow with two microservices:

• Inventory Service - Manages products (create, read, delete)
• Payment Service - Handles order creation and processing

Services communicate asynchronously via Redis Streams.

┌─────────────┐     ┌─────────────┐
│  Inventory  │     │   Payment   │
│  (port 8000)│     │ (port 8001) │
└──────┬──────┘     └──────┬──────┘
       │                   │
       └─────────┬─────────┘
                 │
           ┌─────┴─────┐
           │   Redis   │
           └───────────┘

Flow:

1. Client creates an order via Payment service
2. Payment service fetches product from Inventory service
3. Order is created with "pending" status
4. Background task marks order "completed" after 5 seconds
5. Inventory decreases product quantity via Redis Stream
6. On refund, quantity is restored

• Python 3.8+
• Redis (local or cloud instance)

# Inventory service
cd inventory
pip install -r requirements.txt

# Payment service
cd payment
pip install fastapi uvicorn redis-om python-dotenv requests

Create a .env file in the root directory:

HOST=your-redis-host
PORT=your-redis-port
PASSWORD=your-redis-password

Start each component in separate terminals:

# Terminal 1 - Inventory API
cd inventory
uvicorn main:app --reload --port 8000

# Terminal 2 - Payment API
cd payment
uvicorn main:app --reload --port 8001

# Terminal 3 - Inventory Consumer
cd inventory
python consumer.py

# Terminal 4 - Payment Consumer
cd payment
python consumer.py

curl -X POST http://localhost:8001/orders \
  -H "Content-Type: application/json" \
  -d '{"id": "PRODUCT_ID", "quantity": 1}'

.
├── inventory/
│   ├── main.py       # FastAPI app & product models
│   └── consumer.py   # Redis consumer for order events
├── payment/
│   ├── main.py       # FastAPI app & order models
│   └── consumer.py   # Redis consumer for refund events
└── .env              # Environment variables

• FastAPI - Modern Python web framework
• Redis - In-memory data store
• redis-om - Redis object mapper for Python

MIT