Open Stack

At the summit we found time to squeeze in a revamp of the way we
manage requirements.txt, global-requirements and the versions of
packages we use in the CI system.

https://review.openstack.org/186635 is a cross projects spec, and
hopefully comprehensable :) There's a bunch of work being done
upstream around pip to make it more powerful, which will cleanup some
implementation corners of this spec, but pip as it stands is able to
deliver what we need, with sufficiently evil glue :).

The tl;dr is this:

 - we'll run all jobs with a single set of exact-version constraints
(e.g. if we install requests in a job, it will be '==X')
 - we'll gate changes to that list of versions by running
representative jobs across everything in openstack*/
 - we'll machine-propose changes to that list to give convergence
pressure and avoid building up technical debt

This doesn't change our ability to validate our lower bounds (e.g.
where we need a feature from testtools 1.8.0 but only depend on
>=0.9), nor solve the problem we have today where sometimes a basic
'pip install python-novaclient' is broken due to a broken dependency
being released - but its no worse on either of those problems, and
will supply some infrastructure we might use to tackle them in future.

-Rob

-- 
Robert Collins <rbtcollins at hp.com>
Distinguished Technologist
HP Converged Cloud