Callisto – AI-Assisted Code Review for GitHub

A GitHub agent that performs AI-assisted code reviews by analyzing diffs and providing intelligent comments.

Features

• Receives GitHub webhook events for pull requests
• Analyzes code diffs using AI
• Posts review comments back to GitHub
• Built with FastAPI for high performance
• Async/await support for efficient processing

Setup

GitHub App Installation

1. Install the Callisto GitHub App on your repository:
   • Visit https://github.com/apps/callisto-agent
   • Click "Install" and select the repositories you want to enable code reviews for

Local Development Installation

1. Install dependencies:

poetry install

2. Configure your settings:

cp .env.example .env
# Edit .env with your GitHub token and AI API keys

Running the Agent

Start the development server:

poetry run uvicorn app.main:app --reload --host 0.0.0.0 --port 8000

Or use the Poetry script:

poetry run start

Running Tests

poetry run pytest

Code Quality

Format code:

poetry run black app/ tests/

Lint code:

poetry run flake8 app/ tests/
poetry run mypy app/

Configuration

Set these environment variables in your .env file:

• GITHUB_TOKEN: Your GitHub personal access token
• GITHUB_WEBHOOK_SECRET: Secret for validating GitHub webhooks
• AI_API_KEY: API key for your AI service (e.g., OpenAI)
• AI_MODEL: AI model to use (e.g., gpt-4)
• AI_BASE_URL: (Optional) Custom base URL for OpenAI-compatible APIs (e.g., Azure OpenAI, LocalAI, Ollama)
  • If not set, defaults to OpenAI's official API endpoint
  • Example for Azure: https://YOUR-RESOURCE.openai.azure.com/v1
  • Example for LocalAI: http://localhost:8080/v1

Architecture

• app/main.py: FastAPI application entry point
• app/api/: API endpoints
• app/services/: Business logic (GitHub integration, AI analysis)
• app/config.py: Configuration management
• tests/: Test suite

GitHub Webhook Setup

1. Go to your repository settings → Webhooks
2. Add webhook with URL: https://your-domain.com/webhooks/github
3. Select events: Pull requests
4. Set the webhook secret matching your GITHUB_WEBHOOK_SECRET

Docker

Building Locally

docker build -t callisto .
docker run -p 8000:8000 --env-file .env callisto

GitHub Container Registry

Docker images are automatically built and published to GitHub Container Registry on pushes to main and develop branches.

Pull the latest image:

docker pull ghcr.io/hubble-works/callisto:latest

Available tags:

• latest: Latest build from main branch
• main: Latest build from main branch
• develop: Latest build from develop branch
• v*: Semantic version tags (e.g., v1.0.0)
• main-<sha>, develop-<sha>: Specific commit builds

Run the container:

docker run -p 8000:8000 --env-file .env ghcr.io/hubble-works/callisto:latest

Creating a Release

To publish a versioned release:

1. Create and push a tag:

git tag v1.0.0
git push origin v1.0.0

2. The Docker image will be automatically built and tagged as:
   • ghcr.io/hubble-works/callisto:v1.0.0
   • ghcr.io/hubble-works/callisto:1.0.0
   • ghcr.io/hubble-works/callisto:1.0
   • ghcr.io/hubble-works/callisto:1

License

MIT