Problem:
I’m getting grupos ou módulos ausentes: katello:el8, pulpcore:el8 (missing groups or modules)
when running # dnf module enable katello:el8 pulpcore:el8.
Other relevant data:
I’m following the CentOS Stream 8 steps on this guide Quickstart Guide for Foreman with Katello on RHEL/CentOS.
Did you run the 3 dnf install https://... already before you try to enable the modules?
The metadata for the modules should be part of the katello and pulpcore repos, which get added by the katello-repos-latest.rpm 
Yes, they’re already installed.
Okay, did you use the 3.4 or 3.5 release once? (would take a short look if it also happens to me)
I’ve tried 3.5 but it didn’t work too, so I’m trying 3.4 now with an old snapshot of the VM.
Yup, looks to work, I have tested that on a Rocky Linux 8 container right now, but that shouldn’t really make a difference.
dnf install https://yum.theforeman.org/releases/3.5/el8/x86_64/foreman-release.rpm
dnf install https://yum.theforeman.org/katello/4.7/katello/el8/x86_64/katello-repos-latest.rpm
dnf install https://yum.puppet.com/puppet7-release-el-8.noarch.rpm
dnf module enable katello:el8 pulpcore:el8
dnf module list --enabled
And the result is:
Rocky Linux 8 - AppStream
Name Stream Profiles Summary
perl 5.26 [d][e] common [d], minimal Practical Extraction and Report Language
perl-IO-Socket-SSL 2.066 [d][e] common [d] Perl library for transparent TLS
perl-libwww-perl 6.34 [d][e] common [d] A Perl interface to the World-Wide Web
pki-core 10.6 [e] PKI Core module for PKI 10.6 or later
pki-deps 10.6 [e] PKI Dependencies module for PKI 10.6 or later
postgresql 12 [e] client, server [d] PostgreSQL server and client module
python39 3.9 [d][e] build, common [d] Python programming language, version 3.9
ruby 2.7 [e] common [d] An interpreter of object-oriented scripting language
Foreman 3.5
Name Stream Profiles Summary
foreman el8 [e] installer Foreman module
Katello 4.7
Name Stream Profiles Summary
katello el8 [e] installer Katello module
pulpcore: Fetch, Upload, Organize, and Distribute Software Packages.
Name Stream Profiles Summary
pulpcore el8 [e] Pulpcore module
Maybe retry, and if it still does not work, look at the repo cache and configuration (yum.repos.d), oh and dnf module list of course (to make sure the metadata is up to date also run an extra dnf clean all)
LOL. It turned out I just had to move foreman* katello* puppet* repos to a proper directory (because of network certificates, etc.). Anyways, thanks for the help!
Hah! Fun stuff, good that you figured it out 