I have an app of NextJS frontend server and a backend server(irrelevant in this question), each defined and deployed as docker-compose service.

Since the hostname of the backend server is dynamic by docker DNS, I would have to refer to it by its service name on NextJS server, which resolves it on runtime. I use NextJS's _middleware.ts, which is essentially a convenient way to define a generic API Route as far as I can tell.

This works well for HTTP requests, but for the WebSocket request that initiates the handshake, the WebSocket class expects ws://*** format for the URL argument, which does not go through the NextJS's API Route obviously since it doesn't start with /api.

So it's looking like I:

• have to somehow resolve the DNS hostname
• have to use ws:// format

, and it seems these can't be achieved at the same time for NextJS. Am I missing something?