Foreman 3.0 isn’t released yet. It is coming in the next while.
There are some docs available on our site because we ask the community to help us by testing our release candidates. For example: Foreman 3.0.0 RC2 is available for testing - the second release candidate is available at the moment and the more people who use it and tell us about their experience, the more stable the forthcoming release will be.
We will announce the release as soon as it is ready here, update our site, and on social media/demo etc. You can find all the latest release information and prep in our release announcement section: Release Announcements - TheForeman
What I am trying to say is the OS is less important than what might have happened already on that server before you started to install Foreman.
Foreman server must be installed on a freshly provisioned system that serves no other function except to run Foreman server. The freshly provisioned system must not have the following users provided by external identity providers to avoid conflicts with the local users that Foreman server creates:
Yeah, pretty sure --noop on the first run won’t work. --noop means “don’t actually do any changes to the system”, but the installer relies on the system being actually a working Foreman for that, and on the first run, it is not yet the case.
@ekohl might want to weight in, but I don’t think this is something we’d aim to support.