How to Use fastify-cors to Enable Cross-Domain Access for a Single API Endpoint

Learn how to configure `fastify-cors` to allow cross-domain requests on a specific API endpoint in your Fastify application.
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How to Use fastify-cors to Enable Cross-Domain Access for a Single API Endpoint

In today’s web development landscape, the need for different domains to interact can lead to the necessity of Cross-Origin Resource Sharing (CORS). For instance, you might have a scenario where your server APIs need to be accessible from other domains, but you want to limit this access to just one specific API endpoint. In this guide, we will explore how to accomplish this using the Fastify framework and the fastify-cors package in Node.js.

Understanding the Problem

Imagine you have created an API endpoint that allows users to add products to your application. However, you want to allow the cross-domain request only on this specific endpoint, /product. By default, web browsers restrict cross-origin requests, which is important for security. Therefore, you need to configure your server to allow access for this particular API.

The Solution: Manually Handling CORS or Using fastify-cors

You have two primary methods to allow cross-domain access for just one API:

Manually Set CORS Headers

Using fastify-cors with Specific Configuration

Method 1: Manually Set CORS Headers

This approach allows you to control CORS headers directly in your API handler. Here’s how you can set it up:

[[See Video to Reveal this Text or Code Snippet]]

Explanation:

Access-Control-Allow-Origin: This header specifies which domains are permitted to access your resources. By using "*", you allow all domains, but you could replace "*" with a specific domain if you wish to restrict access further.

Access-Control-Allow-Methods: This specifies the methods allowed when accessing the resource. In this case, we specify that only POST requests are permitted.

Method 2: Using fastify-cors

If you prefer to use the fastify-cors plugin, here’s how to configure it to allow CORS only on the /product endpoint:

[[See Video to Reveal this Text or Code Snippet]]

Explanation:

By registering fastify-cors, you tell Fastify to handle the CORS headers automatically based on the options provided.

The fastify.route method is used to define the /product endpoint, ensuring that it is the only endpoint that accepts POST requests with CORS headers applied.

Conclusion

Configuring CORS in your Fastify applications does not need to be a daunting task. While you can manually set headers in your controller, using the fastify-cors plugin is a straightforward solution that allows for organized and reusable configurations. Whether you choose manual control or the plugin approach, both methods enable you to comply with CORS policies effectively, ensuring your applications remain secure while functioning across different domains.



With this guide, you should be well-equipped to manage cross-domain requests for your specific API endpoint effectively. Don’t hesitate to explore further configurations and modifications based on your application's needs!