How to make a ember app talk to an express api in production with Nqinx

Im working in and Ember App that use a API build with Express js, for development i just run my express api and then run ember server --proxy http://localhost:8000 for example i could be whatever port, so now i have to deploy that to a production environment that im working on, i planing to use nginx, but what i do not know and can't fine is that once a build my ember app for PROD and make nginx serve this files, how do i do to make the ember app knows where to talk to the api.