This override is used by OpenNext to proxy rewritten requests to external services. It is used either in the external middleware (if set) or in the default/splitted server if the middleware is bundled.

If you want to better understand how to implement your own ProxyExternalRequest, the easiest way would be to take a look at the existing included ProxyExternalRequest (opens in a new tab).

Included Proxy External Request

node

This uses node-proxy to proxy the request to the external service.

fetch

This uses fetch to proxy the request to the external service. It doesn't work in Node.js

dummy

This is a dummy implementation that throws a FatalError.