[Pulp-list] erratum.pkglist requirements for empty modules

[Rohan McGovern]

Hi team,

I'm seeking clarification of the required format of "pkglist" when
using the Pulp API to upload erratum units in latest 2-master.

Is the format of pkglist documented anywhere?  If so, could somebody
please point me at that?

If there's no docs which would explain this, then can you please clarify
the behavior for the following scenario:

I have an erratum which contains a module, and that module contains no
RPMs. I put the erratum and modulemd units into a repo.

(1) When I publish that repo with yum_distributor, is the erratum
expected to show up in updateinfo.xml?  i.e. does it make sense in
general for an update with no RPMs (but with a module) to be rendered in
updateinfo.xml; can dnf or other tools make use of it?

(2) If answer to (1) is Yes and the update should be rendered: do I need
to put anything in pkglist to make this happen?

>From reading the code, I think the requirement may be that the uploaded
pkglist contains an (empty) collection for each module, regardless of
whether the module has packages.  Would be good to have that confirmed.

I don't think this behavior is entirely consistent either; e.g. earlier
in _get_pkglist_to_publish, it bails out entirely if the repo contains
no RPMs.  But how does that make sense if erratum with modules (but no
RPMs) are supposed to be rendered?  Why should a module-only erratum be
rendered if in a repo with RPMs, but not rendered if in a repo with no
RPMs?