[openstack-dev] why do we use pip -U in tox.ini?

Sean Dague sean at dague.net
Sun Jan 5 17:17:41 UTC 2014

On 01/05/2014 11:25 AM, Jeremy Stanley wrote:
> On 2014-01-05 10:47:22 -0500 (-0500), Sean Dague wrote:
> [...]
>> It seems like requirements should be sufficient. Forcing -U to the
>> latest all the time seems like it would actually mask a ton of
>> problems, and makes sitepackages = True to be largely useless.
> [...]
> In fact, I believe it was mostly for the benefit of
> sitepackages=True that we started adding it. If my recollection is
> correct, faced with a requirement of foo>=3 and a system install of
> foo==2 pip under tox would refuse to upgrade to meet the stated
> requirement and would instead just use the (non-conforming) version
> from the system (system-wide installs of old Jinja on CentOS 6 seems
> like where nova ran into this).

Well that's really unfortunate.

So if I understand that correctly there is *no* way to configure tox + 
pip to:

  * use site packages if they are sufficient to requirements.txt
  * install packages into venv if they are not (i.e. only use it if you 
have to)

Because that's what I want. And it doesn't seem like a lot to ask.


Sean Dague
Samsung Research America
sean at dague.net / sean.dague at samsung.com

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