Open Stack

On 1/27/2015 2:18 AM, Silvan Kaiser wrote:
> Hello!
> Do dependencies required only in some contexts belong into requirements.txt?
>
> Yesterday we had a short discussion on #openstack-nova regarding how to
> handle optional requirements. This was triggered by our quobyte nova
> driver (https://review.openstack.org/#/c/110722/18), who requires xattr,
> which we therefore added to requirements.txt (as it is provided by the
> requirements project).
>
> Points from the discussion:
> - If we add this we will be adding every requirement for every component
> ---> this becomes to big.
> - Remove this requirement, no optional entries in requirements.txt, a
> 'deployer' has to know what dependencies the components he wants to use have
> ---> Usually he does not know and installation becomes more issue prone
> - Other (in between) ideas???
>
> Please note that this has some urgency, the change set referenced above
> has been in review for months and i'm trying to react asap on comments
> but the deadline is approaching (next week) and if i have to do bigger
> changes I'd like to know as fast as possible...
>
> Best regards
> SIlvan Kaiser
>
>
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In my opinion the volume driver is optional and therefore the dependency 
is optional, it's all based on what the configuration is, the same as 
which DB or RPC backend you use, which is why those dependencies are in 
test-requirements.txt.

While it's more obvious to a deployer that if you're going to configure 
Nova to use MySQL you need some MySQL packages to make it work, any 
deployer that's adding support for this volume driver should also 
probably be testing their deployment scripts, e.g. chef 
cookbooks/recipes, and if they haven't written their script correctly 
they'll find out that it blows up with an ImportError because of a 
missing xattr.  Otherwise, [1].

[1] 
http://troll.me/images/the-most-interesting-man-in-the-world/i-dont-always-test-my-code-but-when-i-do-i-do-it-in-production.jpg

-- 

Thanks,

Matt Riedemann