In this article, we’ll explore how to integrate Firebase authentication into Cloudflare Workers using a zero-dependencies library. By utilizing only web standard APIs, you’ll be able to manage user authentication smoothly. Additionally, we’ll address troubleshooting tips to ensure your implementation runs seamlessly.

Implementation Overview

The Firebase Auth for Cloudflare Workers involves several moving parts. Imagine you are a librarian at a digital library and your job is to ensure that only authorized readers can access restricted books. The process works as follows:

• When a user attempts to access a book, you check if they have a valid library card (the JWT).
• If the card is valid, you grant access to the book.
• If not, you deny access and inform them to obtain a valid card.

In this analogy, the library card represents the Firebase ID token (JWT), and your implementation will verify its authenticity before granting access to resources.

Setting Up Firebase Auth for Cloudflare Workers

To set up the Firebase Auth library, follow these steps:

1. Install the library via npm:

$ npm i firebase-auth-cloudflare-workers

2. Create a new bindings interface:

interface Bindings extends EmulatorEnv {
    PROJECT_ID: string;
    PUBLIC_JWK_CACHE_KEY: string;
    PUBLIC_JWK_CACHE_KV: KVNamespace;
    FIREBASE_AUTH_EMULATOR_HOST: string;
}

3. Implement the verifyJWT function to authenticate users. Below is how the function operates:

const verifyJWT = async (req: Request, env: Bindings): Promise => {
    const authorization = req.headers.get("Authorization");
    if (authorization === null) {
        return new Response(null, { status: 400 });
    }

    const jwt = authorization.replace("Bearer ", "");
    const auth = Auth.getOrInitialize(
        env.PROJECT_ID,
        WorkersKVStoreSingle.getOrInitialize(env.PUBLIC_JWK_CACHE_KEY, env.PUBLIC_JWK_CACHE_KV)
    );
    const firebaseToken = await auth.verifyIdToken(jwt, env);
    return new Response(JSON.stringify(firebaseToken), { headers: { "Content-Type": "application/json" } });
};

Run the Example Code

Here’s a step-by-step guide to run example code for your Firebase auth implementation:

1. Clone the Firebase Auth Cloudflare Workers repository.
2. Navigate into the cloned directory.
3. Install the development dependencies with pnpm:

$ pnpm install

4. Start the Firebase Auth Emulator:

$ pnpm start-firebase-emulator

5. Create a new user in the Emulator UI.
6. Run the local example code:

$ pnpm start-example

7. To get a JWT for the created user, use:

$ curl -s http://localhost:8787/get-jwt | jq .idToken -r

8. Finally, authorize using the JWT.

Troubleshooting

If you encounter issues during your implementation, consider the following troubleshooting tips:

• Ensure that your Firebase Auth Emulator is running correctly.
• Double-check the validity of your JWT; invalid tokens will lead to unauthorized access.
• Inspect the environment variables and keys to make sure they are correctly set.
• For access-related issues, ensure the user exists in the emulator and has the correct permissions.

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Conclusion

By following the outlined steps and utilizing the Firebase Auth library for Cloudflare Workers, you can securely manage user authentication with minimal overhead. If you run into any challenges, refer to the troubleshooting tips to guide your debugging process. Remember, at fxis.ai, we believe that such advancements are crucial for the future of AI, as they enable more comprehensive and effective solutions. Our team is continually exploring new methodologies to push the envelope in artificial intelligence, ensuring that our clients benefit from the latest technological innovations.