Open Stack

Hi,

We recently changed the behavior* of the post pipeline in Zuul to only
run jobs for the most recently merged changes on each project's
branches.  If you were relying on the old behavior where jobs ran on
every merged change, let us know, we can make a new pipeline for that.
But for the typical case, this should result in some improvements:

1) We waste fewer build resources building intermediate build artifacts
(e.g., documentation for a version which is already obsoleted by the
change which landed after it).

2) Races in artifact build jobs will no longer result in old versions of
documentation being published because they ran on a slightly faster node
than the newer version.

If you observe any unexpected behavior as the result of this change,
please let us know in #openstack-infra.

-Jim

* The thing which implements this behavior in Zuul is the
  "supercedent"** pipeline manager[1].  Zuul has had, since the initial
  commit six years ago, a pluggable system for controlling the behavior
  in its pipelines.  To date, we have only had two pipeline managers:
  "dependent" which controls the gate, and "independent" which controls
  everything else.

[1] https://zuul-ci.org/docs/zuul/user/config.html#value-pipeline.manager.supercedent

** It may or may not be named after anyone you know.