speakeasy-sdks / fastapi-example

FastAPI Clerk Auth Example

A demonstration of using Clerk JWT authentication with FastAPI. This example shows how to integrate Clerk's user authentication with a FastAPI backend API.

Configuration

Set the required environment variables:

$ export CLERK_API_SECRET_KEY=your_secret_key

# Set authorized parties (comma-separated list of allowed origins)
$ export CLERK_AUTHORIZED_PARTIES=http://localhost:5173

Installation

python -m venv venv
source venv/bin/activate
pip install -r requirements.txt

Running

fastapi dev

The server will be running at http://localhost:8000.

Frontend Integration

From a Clerk React frontend:

import { useAuth } from '@clerk/clerk-react';

function ApiExample() {
  const { getToken } = useAuth();
  
  const fetchData = async () => {
    if (getToken) {
      // Get the userId or null if the token is invalid
      let res = await fetch("http://localhost:8000/clerk_jwt", {
          headers: {
              "Authorization": `Bearer ${await getToken()}`
          }
      });
      console.log(await res.json()); // {userId: 'the_user_id_or_null'}

      // Get gated data or a 401 Unauthorized if the token is not valid
      res = await fetch("http://localhost:8000/gated_data", {
          headers: {
              "Authorization": `Bearer ${await getToken()}`
          }
      });
      if (res.ok) {
          console.log(await res.json()); // {foo: "bar"}
      } else {
          // Token was invalid
      }
    }
  };
  
  return <button onClick={fetchData}>Fetch Data</button>;
}

API Reference

Available endpoints:

• GET /clerk_jwt - Returns the authenticated user ID
• GET /gated_data - Returns protected data (requires authentication)

⚠️ Production Warning

This project is not optimized for production and does not address all best practices that should be configured in a production app. It serves as a design template and should be given appropriate consideration before being used in production.

Issues to address for production use:

• CORS configuration is specific to development environments
• No HTTPS enforcement
• Minimal error handling (especially 401 errors)
• Using development server settings

For production deployment:

1. Configure proper CORS settings for your specific domains
2. Enforce HTTPS for all API communication
3. Implement comprehensive error handling
4. Use a production-grade web server instead of the built-in development server