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Resolving CORS Policy Issue for Deepgram Transcription on EC2 Deployment

When deploying a monolithic backend on an Amazon EC2 instance with custom domains, you might encounter an issue where your Deepgram transcription route fails due to a CORS policy restriction. This occurs when the 'Access-Control-Allow-Origin' header is not present in the response from your server, leading to blocked requests when trying to access resources across domains from a web client.

Understanding CORS

Cross-Origin Resource Sharing (CORS) is a security feature implemented by browsers to restrict web applications from requesting resources from a different origin than the one that served the web page. In a deployed environment, unlike local development, your requests might be rejected due to the absence of this header, resulting in the CORS policy blocking the requests.

Solution Overview

To resolve this issue, a common approach involves setting up a lightweight proxy server. A proxy can manage the requests and responses between your web client and the Deepgram API, including adding necessary headers to bypass CORS restrictions.

Setting Up a Lightweight Proxy

Here's a practical suggestion for setting up a proxy server:

Proxy Configuration: You can configure your server to route API requests through a proxy that adds the 'Access-Control-Allow-Origin' header to the responses.
Node.js Proxy Example: Deepgram provides a basic Node.js proxy you can adapt for this purpose. This proxy is designed to handle requests through a lightweight setup, ideally suitable for development and production use cases.

Additional Considerations

Payload Size: Ensure that your server and proxy can handle the request and response sizes expected in your application. For instance, with Nginx acting as a reverse proxy, you might need to adjust the client_max_body_size directive to accommodate large payloads.
Security: Caution should be taken to secure your proxy setup to prevent unauthorized access and data leakage. It is your responsibility to secure the proxy application behind your own authentication, or risk others using your Deepgram credit for their own purpose.

Conclusion

Handling CORS issues in a deployed environment requires careful consideration of how you route and proxy requests between your client and external services like Deepgram. Implementing a proxy server is a practical method to ensure that necessary headers are properly managed without exposing your application to security risks.