Option to attach child apps under subdomain

So this is something I’ve come across a few times lately.

I have a root level app:


and a backend app with shared sessions at:


The only way to have this setup work (because cookies are shared) for non-production Environments is setting up custom domains/certificates even though I don’t really care about the url.

But I was thinking it wouldn’t be too hard to extend the current “attach” concept so that you could say “this app is a child of example, use admin as the subdomain”.

The result would be:

Main app: example.fly.dev

Admin app: admin.example.fly.dev

Hopefully that makes sense :eyes: