Feature Request: Listen to unix socket path

[hsblhsn]

First of all thank you for this great project. While using @apollo/gateway, performance is always a concern. Specially when it comes to a cold start. And I believe this project will resolve the issue.

The problem
We have internal tools which uses @apollo/gateway just to integrate all of our subgraphs. Which communicates over unix socket. Because unix socket is twice faster and efficient than regular tcp socket when it comes to inter-process communication. While experimenting with router, we have realized that router does not support unix socket.

Describe alternatives you've considered
Currently we are using apollo-server with @apollo/gateway which uses nodejs http module under the hood. And it has support for unix socket built in. (ex: server.listen('/tmp/gateway')).

[cecton]

@hsblhsn should the subgraphs be contactable by unix sockets too?

[hsblhsn]

At this moment we are not using unix socket for communicating with subgraphs. But it will be a good feature to support.