You could use activation keys that map to certain base/child channels.
Then just run a registration script on the system (shameless plug example:
https://gitlab.com/whowe/spacewalk/blob/master/spacewalk-register.sh)
You may also be able to use distribution channel mappings, but I haven't
used
We are trying to figure out how to automate registering our servers with
specific repositories. Currently, we kickstart new servers and have them
register to spacewalk using a universal activation key that has no channels
associated with it. We did this so that when we create new frozen
