Is that your personal koji instance or fedora's one? If former, make sure you have latest createrepo_c, dnf and such installed and that repodata contains modules.yml

Personal (more accurately: corporate) one. All tools you've mentioned come from CentoOS 8, I didn't upgrade them. I'll check their versions and modules.yml file on tommorow morning. Thanks for helping on New Year day :D

Installed software packages are:

createrepo_c-0.11.0-1.el8.x86_64
dnf-4.0.9.2-5.el8.noarch

I cannot find file named modules.yml anywhere: should it be in /mnt/koji/repos/my-build-tag/latest/x86_64/repodata ?

How did you configure your build target? Do you use external repos? Do they come from centos or you mirror them somehow?

# koji list-external-repos --tag=el8-mydistro-build
Pri External repo name        Mode       URL
--- ------------------------- --------------------------------------------------
5   el8-base                  koji http://mirror.centos.org/centos/8.0.1905/BaseOS/$arch/os/
10  el8-app                   koji http://mirror.centos.org/centos/8.0.1905/AppStream/$arch/os/

Previously I had my own mirror in URL and I've tried another mirror instead
of "mirror.centos.org", but with no effect.

I configured el8-mydistro-build as a build tag for el8-mydistro and also
build tag inherits from el8-mydistro. I used the same configuration as in
previous Koji installation.

Perchaps I should change Mode setting?

We'll try Fedora 31 as a system base for Koji, it has hot createrepo_c 0.15.1 and dnf 4.2.9. Upgrading createrepo_c/dnf for Centos8 was too difficult.

Result is the same: new line in output appeared:

DEBUG util.py:596:    - package perl-version-6:0.99.24-1.module_el8.0.0+50+c3b345cd.x86_64 is filtered out by modular filtering

With merge_mode set to "bare", mock was able to install perl and my build has finally finished (yay!)

Most supprising and irritating conclusion is: CentOS 8 is too old for Koji to build packages for CentOS 8 :/

Hello,
I ran into the exact same problem. How do you set the merge_mode? koji edit-external-repo --help doesn't show that as an option, and koji list-external-repos --tag=dist-el8-build does not show the "Mode" column for me. I'm using koji 1.21.0 on the client and 1.20.1 on the hub.
Thanks,
-Mat

My hub and client are both 1.21.0 and there is -m MODE option bot in add- and edit- command.

I can't find right now in which version "bare" mode support was added; maybe you may turn it on in 1.20 by manually editing tag_external_repos table in datbase?

bare mode is here from 1.18. 1.21 introduced support for editing it. Before, you need to remove external repo and add it again (add-external-repo has -m option from earlier).

(Original issue for bare mode: #1404)

Looks like the version of createrepo_c on EL7 is too old: createrepo_c-0.10.0-20.el7 but the changelog says --pkgorigins was added in 0.14.1-1.

I couldn't build the newest createrepo_c for EL7, but was able to build 0.14.2, which was enough to create repos I could use for CentOS 8 building.

Don't forget to enable libmodulemd support in it, otherwise you won't be able to build many packages which have dependencies from default module streams

Closing for now as there seem to be no other problems.