An intelligent GitHub App that automatically reviews pull requests using Google's Gemini AI. Built with Python, Flask, and the GitHub API.

• 🔍 Automatic Code Review: Reviews code in pull requests using Gemini AI
• 🚀 Real-time Processing: Responds to PR events instantly via webhooks
• 🛡️ Secure: Proper webhook signature verification and GitHub App authentication
• ⚡ Async Support: Optional async version for better performance
• 🧪 Local Testing: Easy local development with ngrok
• 📦 Easy Deployment: Ready for Vercel, Heroku, or any Python hosting

git clone <your-repo>
cd github-ai-reviewer-python

# Run the setup script
python setup.py

# Create virtual environment
python -m venv venv
source venv/bin/activate  # On macOS/Linux
# venv\Scripts\activate   # On Windows

# Install dependencies
pip install -r requirements.txt

# Copy environment template
cp .env.example .env

Edit .env file with your values:

GITHUB_APP_ID=your_app_id_here
GITHUB_INSTALLATION_ID=your_installation_id_here
WEBHOOK_SECRET=your_webhook_secret_here
GEMINI_API_KEY=your_gemini_api_key_here

1. Go to GitHub Settings → Developer settings → GitHub Apps → New GitHub App
2. Fill in the details:
   • Name: AI Code Reviewer (Dev)
   • Homepage URL: http://localhost:5000
   • Webhook URL: https://your-ngrok-url.ngrok.io/webhook
   • Webhook Secret: Generate a random string
3. Permissions:
   • Repository permissions:
     • Contents: Read
     • Pull requests: Write
     • Metadata: Read
4. Subscribe to events: Pull request
5. Download the private key and save as private-key.pem

# Terminal 1: Start ngrok
ngrok http 5000

# Terminal 2: Start the server
python server.py

# Or use the async version for better performance
python async_server.py

1. Update your GitHub App webhook URL with the ngrok URL
2. Create a test pull request in a repository where the app is installed
3. Watch the magic happen! 🎉

github-ai-reviewer-python/
├── server.py              # Main Flask server
├── async_server.py        # Async version with Quart
├── setup.py              # Setup script
├── test_server.py        # Unit tests
├── requirements.txt      # Python dependencies
├── .env.example         # Environment template
├── vercel.json          # Vercel deployment config
├── private-key.pem      # GitHub App private key (you add this)
└── README.md           # This file

# Run unit tests
python test_server.py

# Test health endpoint
curl http://localhost:5000/health

# Test webhook (with proper signature)
curl -X POST http://localhost:5000/webhook \
  -H "Content-Type: application/json" \
  -H "X-GitHub-Event: pull_request" \
  -d '{"action": "opened", "pull_request": {...}}'

# Install Vercel CLI
npm i -g vercel

# Deploy
vercel --prod

# Set environment variables in Vercel dashboard

# Create Heroku app
heroku create your-app-name

# Set environment variables
heroku config:set GITHUB_APP_ID=your_app_id
heroku config:set GITHUB_INSTALLATION_ID=your_installation_id
heroku config:set WEBHOOK_SECRET=your_webhook_secret
heroku config:set GEMINI_API_KEY=your_gemini_key

# Deploy
git push heroku main

# Build image
docker build -t github-ai-reviewer .

# Run container
docker run -p 5000:5000 --env-file .env github-ai-reviewer

The reviewer currently supports these file extensions:

• Python: .py
• JavaScript/TypeScript: .js, .ts, .jsx, .tsx
• Java: .java
• C/C++: .c, .cpp
• Go: .go
• Rust: .rs
• PHP: .php
• Ruby: .rb

Edit the review_with_gemini() function to customize the AI prompts:

prompt = f"""
Please review this {filename} file for:
1. Code quality and best practices
2. Potential bugs or security issues
3. Performance improvements
4. Code style and readability

Your custom instructions here...
"""

• ✅ Webhook signature verification
• ✅ GitHub App authentication (more secure than personal tokens)
• ✅ Environment variable protection
• ✅ Input validation and sanitization
• ✅ Error handling and logging

• Simple Flask implementation
• Synchronous processing
• Good for low-traffic scenarios

• Uses Quart (async Flask)
• Concurrent file processing
• Better for high-traffic scenarios
• Faster response times

1. "Invalid signature" error

   • Check your WEBHOOK_SECRET matches GitHub App settings
   • Ensure webhook URL is correct

2. "Authentication failed" error

   • Verify GITHUB_APP_ID and GITHUB_INSTALLATION_ID
   • Check private-key.pem file exists and is valid

3. "Gemini API error"

   • Verify GEMINI_API_KEY is correct
   • Check API quota and billing

4. Webhook not receiving events

   • Ensure ngrok is running and URL is updated in GitHub App
   • Check GitHub App is installed on the repository

# Enable debug logging
export FLASK_ENV=development
python server.py

1. Fork the repository
2. Create a feature branch
3. Make your changes
4. Add tests
5. Submit a pull request

MIT License - see LICENSE file for details

• GitHub API and PyGithub library
• Google Gemini AI
• Flask/Quart web frameworks
• ngrok for local development

Happy coding! 🚀 If you find this useful, please give it a ⭐!