ayz-auth 0.1.0

FastAPI middleware for Stytch B2B authentication with Redis caching

ayz-auth

FastAPI middleware for Stytch B2B authentication with Redis caching.

Overview

ayz-auth is a lightweight, production-ready authentication middleware for FastAPI applications using Stytch B2B authentication services. It provides session token verification with Redis caching for optimal performance and includes comprehensive error handling and logging.

Features

• 🔐 Stytch B2B Integration: Seamless integration with Stytch B2B authentication
• ⚡ Redis Caching: Intelligent caching to reduce API calls and improve performance
• 🚀 FastAPI Native: Built specifically for FastAPI with proper dependency injection
• 📝 Type Safe: Full Pydantic models with type hints throughout
• 🛡️ Security First: Secure token handling with configurable logging levels
• 🔧 Configurable: Environment-based configuration with sensible defaults
• 📊 Comprehensive Logging: Structured logging with sensitive data protection
• 🧪 Well Tested: Comprehensive test suite with mocking support

Installation

pip install ayz-auth

Or with UV:

uv add ayz-auth

Quick Start

1. Environment Configuration

Create a .env file or set environment variables:

STYTCH_PROJECT_ID=your_project_id
STYTCH_SECRET=your_secret_key
STYTCH_ENVIRONMENT=test  # or "live" for production
REDIS_URL=redis://localhost:6379

2. Basic Usage

from fastapi import FastAPI, Depends
from ayz_auth import verify_auth, StytchContext

app = FastAPI()

@app.get("/protected")
async def protected_route(user: StytchContext = Depends(verify_auth)):
    return {
        "message": f"Hello {user.member_email}",
        "member_id": user.member_id,
        "organization_id": user.organization_id
    }

@app.get("/user-info")
async def get_user_info(user: StytchContext = Depends(verify_auth)):
    return {
        "member_id": user.member_id,
        "email": user.member_email,
        "name": user.member_name,
        "organization_id": user.organization_id,
        "session_expires_at": user.session_expires_at,
        "authentication_factors": user.authentication_factors
    }

3. Optional Authentication

For endpoints that work with or without authentication:

from typing import Optional
from ayz_auth import verify_auth_optional

@app.get("/optional-auth")
async def optional_route(user: Optional[StytchContext] = Depends(verify_auth_optional)):
    if user:
        return {"message": f"Hello {user.member_email}"}
    else:
        return {"message": "Hello anonymous user"}

4. Custom Authentication Requirements

Create custom dependencies with additional requirements:

from ayz_auth import create_auth_dependency

# Require specific custom claims
admin_auth = create_auth_dependency(required_claims=["admin"])
moderator_auth = create_auth_dependency(required_claims=["moderator", "verified"])

# Require specific authentication factors
mfa_auth = create_auth_dependency(required_factors=["mfa"])

@app.get("/admin")
async def admin_route(user: StytchContext = Depends(admin_auth)):
    return {"message": "Admin access granted"}

@app.get("/sensitive")
async def sensitive_route(user: StytchContext = Depends(mfa_auth)):
    return {"message": "MFA verified access"}

Configuration

All configuration is handled through environment variables with the STYTCH_ prefix:

Variable	Default	Description
STYTCH_PROJECT_ID	required	Your Stytch project ID
STYTCH_SECRET	required	Your Stytch secret key
STYTCH_ENVIRONMENT	test	Stytch environment (test or live)
STYTCH_REDIS_URL	redis://localhost:6379	Redis connection URL
STYTCH_REDIS_PASSWORD	None	Redis password (if required)
STYTCH_REDIS_DB	0	Redis database number
STYTCH_REDIS_SSL	False	Use SSL for Redis connection
STYTCH_CACHE_TTL	300	Cache TTL in seconds (5 minutes)
STYTCH_CACHE_PREFIX	ayz_auth	Redis key prefix
STYTCH_LOG_LEVEL	INFO	Logging level
STYTCH_LOG_SENSITIVE_DATA	False	Log sensitive data (never in production)
STYTCH_REQUEST_TIMEOUT	10	Request timeout in seconds
STYTCH_MAX_RETRIES	3	Maximum retry attempts

StytchContext Model

The StytchContext model contains all the essential session data from Stytch:

class StytchContext(BaseModel):
    # Core identifiers
    member_id: str
    session_id: str
    organization_id: str
    
    # Session timing
    session_started_at: datetime
    session_expires_at: datetime
    session_last_accessed_at: datetime
    
    # Member information
    member_email: Optional[str]
    member_name: Optional[str]
    
    # Session metadata
    session_custom_claims: Dict[str, Any]
    authentication_factors: List[str]
    
    # Utility properties
    @property
    def is_expired(self) -> bool: ...
    
    @property
    def time_until_expiry(self) -> Optional[float]: ...

Error Handling

The middleware provides structured error responses:

# 401 Unauthorized - Missing or invalid token
{
    "error": "authentication_failed",
    "message": "Authorization header is required",
    "type": "token_extraction"
}

# 401 Unauthorized - Token verification failed
{
    "error": "authentication_failed", 
    "message": "Invalid or expired session token",
    "type": "token_verification"
}

# 503 Service Unavailable - Stytch API issues
{
    "error": "service_unavailable",
    "message": "Authentication service temporarily unavailable", 
    "type": "stytch_api"
}

# 403 Forbidden - Insufficient permissions (custom auth)
{
    "error": "insufficient_permissions",
    "message": "Missing required claims: ['admin']",
    "type": "authorization"
}

Caching Strategy

The middleware implements a two-tier verification system:

1. Redis Cache Check: Fast lookup of previously verified tokens
2. Stytch API Fallback: Fresh verification when cache misses

Cache entries automatically expire based on the session expiration time, ensuring security while maximizing performance.

Integration with Your User System

Since the middleware only returns Stytch session data, you can easily integrate it with your existing user system:

from your_app.models import User
from your_app.database import get_user_by_stytch_member_id

@app.get("/profile")
async def get_profile(stytch: StytchContext = Depends(verify_auth)):
    # Use the member_id to fetch your user data
    user = await get_user_by_stytch_member_id(stytch.member_id)
    
    if not user:
        raise HTTPException(404, "User not found")
    
    # Check permissions using your user model
    if "read_profile" not in user.permissions:
        raise HTTPException(403, "Insufficient permissions")
    
    return {
        "stytch_data": stytch.to_dict(),
        "user_data": user.to_dict()
    }

Development

Running Tests

# Install development dependencies
uv sync --dev

# Run tests
pytest

# Run tests with coverage
pytest --cov=ayz_auth

Code Quality

# Format code
black src/ tests/
isort src/ tests/

# Lint code
ruff check src/ tests/

# Type checking
mypy src/

Contributing

1. Fork the repository
2. Create a feature branch
3. Make your changes
4. Add tests for new functionality
5. Ensure all tests pass
6. Submit a pull request

License

MIT License - see LICENSE file for details.

Support

For issues and questions:

• GitHub Issues: https://github.com/brandsoulmates/stytch-auth/issues
• Documentation: https://github.com/brandsoulmates/stytch-auth