Can't understand ember auth

Hey, I’ve been using ember with node+express since 2 months ago.

I’ve developed an small app, now is time to add user auth to it but I can’t figure out how to do this.

There are a few questions I have:

1.- In SPA apps, where there’s only index.html, I include all .js ember files. So, the user could be able to see all the app logic without auth?. How can I add the libs only when the user has been auth?

2.- What’s the right way to auth in ember? I haven’t seen a solution in official documentation.

3.- How the frontend comunicates with the backend, what’s the logic here? It’s in every route?

Also I’m looking for an example or tutorial.

Thanks you!