Open Stack

On Mon, 2013-07-08 at 15:53 +0800, Thomas Goirand wrote:
> Hi,
> 
> Since python-sqlalchemy 0.8.2 has been uploaded to Sid, Quantum is
> uninstallable there right now (see #715294).
> 
> I am wondering: what's wrong with sqlalchemy >= 0.8, so that it is
> written explicitly in the requirements that we shouldn't use it? Is
> there a chance that having such a version of sqlalchemy will make all of
> OpenStack grizzly fail? What are the consequences? Would it be safe to
> simply patch the requirements file and ignore this?

Don't really have a comment on the specifics, but ...

We should definitely avoid being overly aggressive with our version caps
because they cause issues like this.

The principle should be that we take the time to understand the
dependencies versioning scheme and use a the version cap which we think
will insulate us from incompatible changes without preventing us from
using perfectly compatible versions.

That's not always easy. If a library makes a commitment to changing it's
major version if it makes an incompatible change, you can do:

  >=x.y.z,<x+1

but there are cases where we know that minor version number increases
are very likely to include incompatible changes so we do:

  >=x.y.z,<x.y+1

That's the case with sqlalchemy, I guess. Before 0.8 ever existed, we
expected that 0.8 would contain incompatible changes.

Cheers,
Mark.