🚀 Redis Order System (FastAPI + Redis Streams)

A high-performance backend system built using FastAPI, Redis, and PyTest.
This project demonstrates real-world backend engineering including Redis caching, Redis Streams-based asynchronous order processing, standardized API responses, and full automated testing.

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🛠️ Tech Stack Used

1. FastAPI Framework

• High-performance async web framework
• Automatic Swagger UI documentation
• Dependency Injection support

2. Pydantic Models

• Strong request validation
• Standard response errors on validation failure
• Used only for handling API input payloads

3. Custom Exception Handling

• All API errors return a Standard Response Format
• Global error handlers implemented

4. Custom Response Handling

• All API return a Standard Response Format

5. Redis Features

Used extensively across the project:

Feature	Usage
GET / SET	Product caching, session tokens
EXPIRE / TTL	Session token expiry
HSET / HGET	Product data
Pipeline	Batch Redis operations
Streams (XADD / XREADGROUP / XACK)	Order queue processing
Sets	Internal unique key store

6. PyTest

• Session-scoped fixtures
• Worker integration testing
• E2E test execution
• Clean isolation between test runs

7. Swagger UI

Auto-generated interactive API documentation via FastAPI. URL: http://127.0.0.1:8000/docs

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📘 API Endpoints Overview

1️⃣ System Health

GET /system-health Checks if the backend is running.

2️⃣ User Login (Generates Session Token)

POST /users/login

• Validates user credentials
• Generates a session token stored in Redis (No JWT)
• Token TTL controlled by Redis
• Returns token in standard response format

3️⃣ Get All Products

GET /products Headers: Authorization: Bearer

4️⃣ Get Product by ID

GET /products/{product_id} Headers: Authorization: Bearer

5️⃣ Set Product Stock

POST /products/setstock Headers: Authorization: Bearer

6️⃣ Place Order (Redis Stream Event)

POST /orders/place-order Headers: Authorization: Bearer This:

• Pushes an order event into a Redis Stream
• Background worker listens and processes orders
• Worker acknowledges processed messages

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⚙️ Installation (Local Machine)

1️⃣ Install System Requirements

• Python 3.12
• Redis Server (latest stable)

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🐍 Setup Virtual Environment

Activate environment: source venv/bin/activate
Install project dependencies: pip install -r requirements.txt
▶️ Running the Project
Terminal 1 – Start FastAPI Application
uvicorn app.main:app
Terminal 2 – Start Background Redis Worker
python -c "from app.workers.order_placed_worker import runOrderPlacedStreamConsumerGroupWorker1; runOrderPlacedStreamConsumerGroupWorker1()"
pytest -v tests/test_all_things_in_one_way.py \
    --disable-warnings \
    --maxfail=0 \
    -W ignore::DeprecationWarning \
    -s