[Pulp-dev] problems with publishers in Pulp 3

[Brian Bouterse]

Thank you for writing this out. The most significant issue I read in this
is that 3 of the 9 plugins are having their users take steps that aren't
adding any value in their workflow. They want to (and have an opportunity
to) take repository version content and expose it directly. They don't need
Publications or Publishers. If they need no metadata, instead of a
"pass-through" publication it would be easier to have a Distribution refer
to a RepositoryVersion directly and remove the "pass-through" feature. They
the user could skip this step (
https://github.com/pulp/pulp_ansible#create-a-publication ) and instead
post the RepositoryVersion reference as part of the Distributor itself (
https://github.com/pulp/pulp_ansible#create-a-distribution-for-the-publication
).

The second issue I read here is that having users CRUD a publisher and then
call that publisher is not as helpful/useful as CRUDing the resulting
Publication directly. One practical issue related to this is the saving of
the "publish" parameters. How do we store those over time? Our modeling
choices have made this a bit challenging because Publication's aren't
plugin controlled. A simple remedy is to have plugins provide various
Publication objects instead of Publishers. These Publications would be
managed by Master/Detail and when created it would run the task that
creates the Publication and return the 202. This simplifies Pulp in that
the options that were used to create the publication can be saved on the
Publication as provided by various plugins. It also allows users to take
one less step (they don't need to make a publisher to then make a
publication). Instead users that need metadata generated can do so with one
step, making the publication. So my main question is, can anyone remember
why we didn't use Master/Detail in this area originally?

I believe these are changes we should explore. The top one is a pretty
simple add on and mostly not a breaking change. The bottom one would be a
larger change, but one that I believe we could make and should seriously
consider pre 3.0 GA.



On Mon, Apr 8, 2019 at 7:42 AM Dennis Kliban <dkliban at redhat.com> wrote:

> TLDR:
>
> Auto-distribution of publications is performed implicitly instead of
> explicitly.
> Plugins that don't generate metadata during publish have to provide a
> generic publisher.
> Users have to keep track of publishers to make sure auto-distribution of
> new publications works.
>
> More background:
>
> Publishers in Pulp 3 serve three distinct functions:
>   - store configuration for how a publication should be created
>   - create publications using the configuration
>   - update any distributions that are supposed to be auto updated with new
> publications of a repository (auto distribution).
>
> Ansible, Docker, and Maven plugins do not generate any metadata when
> creating a publication. So their publishers don't need to store any
> configuration. Users of these plugins only get two benefits from publishers:
>   - create publications using the configuration
>   - update any distributions that are supposed to be auto updated with new
> publications of a repository (auto distribution).
>
> The publications created by the publishers of these plugins could be
> created using a single generic publish task. So the only remaining benefit
> of a publisher for these plugins is the auto-distiribution that occurs when
> a Distribution has a repository and a pubisher configured. The only way
> this feature is documented right now is with the help text on the
> 'repository' and 'publisher' fields of Distributions.
>
> Does anyone else see these as problems with the Publishers?
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