Why is *.fly.dev redirecting to https automatically?

I’m basically running the tutorial version of an Elixir/Phoenix application. When I try to visit the app at http://[app].fly.dev, it automatically redirects to https://[app].fly.dev. This is ideal, of course, but I don’t understand why.

I don’t have force_ssl: ... set in my Phoenix Endpoint config. I still have the [[services.ports]] handlers = [http] port = 80 in my fly.toml. I don’t see a strict-transport-security header on any responses (e.g., if the redirect came from the fly-proxy, I could expect some network log, perhaps).

This is, of course, what I want to happen, but I don’t understand why it is happening. I don’t see where it is configured. The reason I want to know is that when I setup a custom domain with fly certs, it works, but I can access http://… on my custom domain. If I didn’t have to configure anything to force tls on the [app].fly.dev URL, I’d like to know how to also not configure anything to force tls on my custom domain. Is that possible? (I know I can attempt to handle this within my application, but I’m trying to clear up some confusions before I do).

Thank you for any help/info you can provide :smiley:

This is a feature of .dev TLD:

If you try it with curl, you shouldn’t get the redirect.