Filtering out Events whose dep_on is None could have better performance, because dep_on of most of the builds are not None in most of the time.

EDIT:

Maybe the query could be

select from Event where state != ArtifactBuildState.PLANNED.value and dep_on is null and build_args != ''

I would prefer to move above three if to _build_first_batch and just pass build_args and repo_urls. From the method name and description, we know that this method is responsible for submitting container build to Koji. Selecting proper ArtifactBuild to submit could be moved out of this method.

But that would mean I would have to duplicate those three ifs also in container_task_state_change.py to get the build_args there...

Looks good to me. Some comments are added, they are my thoughts emerged in my mind while I'm reading these changes, but it is not a big problem I think.

I think we can abstract it to a method

def ArtifactBuild.get_buildables(self, dep_on=None, ...):
    pass

Updated, it now gets only builds with dep_on=None instead of filtering that in the python code.

After discussion on IRC, we will keep the current code in build_image_artifact_build including the three ifs.