[Starlingx-discuss] upstream -infra queue setup might need tweaking to handle cross-project dependencies

[Chris Friesen]

Hi all,

Recently we had an issue where https://review.openstack.org/#/c/578414/ was 
given +W before https://review.openstack.org/#/c/578413/ (which it was dependent 
on and was in another project) was merged.

This caused https://review.openstack.org/#/c/578414/ to get "stuck" requiring a 
core to remove the workflow approval and re-add it, which "woke up" the process 
and got it merged.

Talking with the folks on #openstack-infra, they said that the problem was that 
the two projects don't share a gate queue.  In that case you can't approve a 
change with "depends-on" until the depended-on change has merged.

The automated way to handle this is to have all the potentially interdependent 
projects share a queue by specifying a common queue name.  The example given was 
the "integrated" queue for nova and friends, as specified at 
https://git.openstack.org/cgit/openstack-infra/project-config/tree/zuul.d/projects.yaml#n108

This does potentially introduce merge delays since it will serialize merges 
across all the projects that share a queue, but for tightly-coupled projects it 
might make sense.

Chris