Question:
I have a Katello 3.16.0 server, “hardhat2”, and I would like to rename it to “hardhat” safely. It’s using an appropriate wildcard certificate for certs-server-cert and certs-server-ca-cert.
The IP address of the server will not be changing.
Wondering what I’ll need to actually change to make this happen 
Foreman and Proxy versions:
Foreman 2.1.0
Foreman and Proxy plugin versions:
Katello 3.16.0
foreman-tasks 2.0.2
Distribution and version:
CentOS 7, 64-bit
Other relevant data:
Thanks for asking this question before taking a shot in the dark! Changing the hostname of a Katello installation is pretty serious business since we have strict usage of SSL across all components, and down through the registered Content Hosts.
A utility called katello-change-hostname is installed on every Katello server and provides the functionality you’re looking for. Be aware that performing this change requires that clients are re-registered after installing the new katello-ca-consumer RPM after the hostname-change utility completes. Be sure to take a backup due to the impact of this change.
Unfortunately the utility is lacking true documentation, but typing katello-change-hostname -h will show how can you invoke it.
I gave it a shot and was unfortunately bitten as I didn’t make sure the new name resolved before starting the process…
Unable to resolve forward DNS for hardhat.example.com
and then it bailed. I’m now restoring from backup and will give it another shot once that finishes.
I noticed when using katello-change-hostname it will always use
“foreman-installer --scenario katello -v --disable-system-checks --certs-regenerate=true --foreman-proxy-register-in-foreman true”
Would be nice if you can add custom values as in my case I dont want puppet installed. (I now I can just rerun foreman-installer but now I have additional work to fix my puppet agent running on the machine)
BUT
I can confirm katello-change-hostname DOES WORK