alt Hacker NewsKnowing what DNS names are actually used.
EDIT: that's the flip side of supporting HTTPS that's not well-known among developers - by acquiring a legitimate certificate for your service to enable HTTPS, you also announce to the entire world, through a public log, that your service exists.
I don't really see how this is a flip-side. If you're putting something on the web, presumably you want it to be accessed by others, so this is actually a benefit.
If you didn't want others to access your service, maybe consider putting it in a private space.