spotizerr-dev/SSO_IMPLEMENTATION.md

# SSO (Single Sign-On) Implementation for Spotizerr

## Overview

I have successfully implemented comprehensive SSO backend logic for Google and GitHub authentication in your Spotizerr application. This implementation integrates seamlessly with your existing JWT-based authentication system.

## What Was Implemented

### 1. Dependencies Added
- Added `fastapi-sso==0.18.0` to `requirements.txt`

### 2. New Files Created
- `routes/auth/sso.py` - Complete SSO implementation with Google & GitHub support
- `routes/auth/sso_example.py` - Example client for testing SSO functionality
- `SSO_IMPLEMENTATION.md` - This documentation file

### 3. Updated Files
- `routes/auth/__init__.py` - Extended User model to support SSO fields
- `routes/auth/auth.py` - Updated authentication status to include SSO info
- `routes/auth/middleware.py` - Added SSO endpoints to public paths
- `AUTH_SETUP.md` - Comprehensive SSO setup documentation
- `requirements.txt` - Added fastapi-sso dependency

### 4. Extended User Model
The `User` class now supports:
- `sso_provider` - Which SSO provider was used (google/github)
- `sso_id` - Provider-specific user ID
- `is_sso_user` - Boolean flag for frontend use

## Environment Configuration

Create a `.env` file with the following variables:

```bash
# Basic Authentication
ENABLE_AUTH=true
JWT_SECRET=your-super-secret-jwt-key-change-in-production
JWT_EXPIRATION_HOURS=24
DEFAULT_ADMIN_USERNAME=admin
DEFAULT_ADMIN_PASSWORD=your-secure-password

# SSO Configuration
SSO_ENABLED=true
SSO_BASE_REDIRECT_URI=http://localhost:8000/api/auth/sso/callback
FRONTEND_URL=http://localhost:3000

# Google SSO (optional)
GOOGLE_CLIENT_ID=your-google-client-id
GOOGLE_CLIENT_SECRET=your-google-client-secret

# GitHub SSO (optional)
GITHUB_CLIENT_ID=your-github-client-id
GITHUB_CLIENT_SECRET=your-github-client-secret
```

## API Endpoints Added

### SSO Status & Information
- `GET /api/auth/sso/status` - Get SSO configuration and available providers

### Google SSO
- `GET /api/auth/sso/login/google` - Initiate Google OAuth flow
- `GET /api/auth/sso/callback/google` - Handle Google OAuth callback (automatic)

### GitHub SSO  
- `GET /api/auth/sso/login/github` - Initiate GitHub OAuth flow
- `GET /api/auth/sso/callback/github` - Handle GitHub OAuth callback (automatic)

### SSO Management
- `POST /api/auth/sso/unlink/{provider}` - Unlink SSO provider from user account

### Enhanced Authentication Status
- `GET /api/auth/status` - Now includes SSO status and available providers

## OAuth Provider Setup

### Google SSO Setup

1. Go to [Google Cloud Console](https://console.cloud.google.com/)
2. Create a new project or select existing one
3. Enable Google+ API
4. Go to "Credentials" → "Create Credentials" → "OAuth 2.0 Client IDs"
5. Configure OAuth consent screen
6. Set authorized redirect URIs:
   - Development: `http://localhost:8000/api/auth/sso/callback/google`
   - Production: `https://yourdomain.com/api/auth/sso/callback/google`
7. Copy Client ID and Client Secret to environment variables

### GitHub SSO Setup

1. Go to GitHub Settings → Developer settings → OAuth Apps
2. Click "New OAuth App"
3. Fill in application details:
   - Application name: Your app name
   - Homepage URL: Your app URL
   - Authorization callback URL:
     - Development: `http://localhost:8000/api/auth/sso/callback/github`
     - Production: `https://yourdomain.com/api/auth/sso/callback/github`
4. Copy Client ID and Client Secret to environment variables

## How It Works

### SSO Flow
1. User clicks "Login with Google/GitHub" button in frontend
2. Frontend redirects to `/api/auth/sso/login/{provider}`
3. User is redirected to provider's OAuth consent screen
4. After consent, provider redirects to `/api/auth/sso/callback/{provider}`
5. Backend validates OAuth code and retrieves user info
6. System creates or updates user account
7. JWT token is generated and set as HTTP-only cookie
8. User is redirected to frontend with authentication complete

### User Management
- **New SSO Users**: Automatically created with `user` role (first user gets `admin`)
- **Existing Users**: SSO provider linked to existing account by email
- **Username Generation**: Uses email prefix, ensures uniqueness
- **Password**: SSO users have `password_hash: null` (cannot use password login)

## Testing the Implementation

### 1. Install Dependencies
```bash
pip install fastapi-sso==0.18.0
```

### 2. Configure Environment
Set up your `.env` file with the OAuth credentials from Google/GitHub

### 3. Start the Application
```bash
uvicorn app:app --reload
```

### 4. Test SSO Status
```bash
curl http://localhost:8000/api/auth/sso/status
```

### 5. Test Authentication Flow
1. Visit `http://localhost:8000/api/auth/sso/login/google` in browser
2. Complete OAuth flow
3. Should redirect to frontend with authentication

### 6. Programmatic Testing
Run the example script:
```bash
python routes/auth/sso_example.py
```

## Security Features

### Production Ready
- **HTTPS Support**: Set `allow_insecure_http=False` in production
- **Secure Cookies**: HTTP-only cookies with secure flag
- **CORS Configuration**: Properly configured for your frontend domain
- **Token Validation**: Full server-side JWT validation
- **Provider Verification**: Validates OAuth responses from providers

### OAuth Security
- **State Parameter**: CSRF protection in OAuth flow
- **Redirect URI Validation**: Strict redirect URI matching
- **Token Expiration**: Configurable JWT token expiration
- **Provider Validation**: Ensures tokens come from legitimate providers

## Integration Points

### Frontend Integration
The authentication status endpoint now returns SSO information:

```json
{
  "auth_enabled": true,
  "sso_enabled": true,
  "sso_providers": ["google", "github"],
  "authenticated": false,
  "user": null,
  "registration_enabled": true
}
```

### User Data Structure
SSO users have additional fields:

```json
{
  "username": "john_doe",
  "email": "john@example.com",
  "role": "user",
  "sso_provider": "google",
  "is_sso_user": true,
  "created_at": "2024-01-15T10:30:00",
  "last_login": "2024-01-15T10:30:00"
}
```

## Error Handling

The implementation includes comprehensive error handling for:
- Missing OAuth credentials
- OAuth flow failures
- Provider-specific errors
- Invalid redirect URIs
- Network timeouts
- Invalid tokens

## Backwards Compatibility

- **Existing Users**: Unaffected, can still use password authentication
- **Existing API**: All existing endpoints work unchanged
- **Configuration**: SSO is optional, system works without it
- **Database**: Extends existing user storage, no migration needed

## Next Steps

1. **Configure OAuth Apps**: Set up Google and GitHub OAuth applications
2. **Update Frontend**: Add SSO login buttons that redirect to SSO endpoints
3. **Test Flow**: Test complete authentication flow end-to-end
4. **Production Setup**: Configure HTTPS and production redirect URIs
5. **User Management**: Add SSO management to your admin interface

## Support

The implementation follows FastAPI best practices and integrates cleanly with your existing authentication system. All SSO functionality is optional and gracefully degrades if not configured.

For issues or questions, check the comprehensive documentation in `AUTH_SETUP.md` or refer to the example client in `routes/auth/sso_example.py`.