[openstack-dev] [all] re-introducing twisted to global-requirements

Doug Hellmann doug at doughellmann.com
Fri Jan 8 20:13:15 UTC 2016

Excerpts from Jim Rollenhagen's message of 2016-01-08 11:52:51 -0800:
> On Fri, Jan 08, 2016 at 02:08:04PM -0500, Jay Pipes wrote:
> > On 01/07/2016 07:38 PM, Jim Rollenhagen wrote:
> snippity snip snip
> > >We haven't made it a dep for anything yet, only added to g-r.
> > 
> > According to Dims, not to g-r, but to u-c, right Dims? Not sure if that
> > makes functionally any difference, though (pun intended).
> Both. https://review.openstack.org/#/c/220268/
> This thread was originally about twisted, which is added to u-c with the
> introduction of mimic.
> > >However, now that you mention that, a really ambitious goal would be to
> > >add a rabbit interface to mimic, and functionally test the API server
> > >(that it sends the right messages, etc). Another would be to mimic
> > >(Neutron, Glance) and test Ironic by itself.
> > 
> > So you would reimplement AMQP communication protocols using an in-memory
> > data store for queues. Sounds like an even greater surface area for bugs to
> > be introduced.
> > 
> > >Last, I frankly don't understand why there's
> > >such heavy opposition to the ironic team using an additional tool for
> > >testing.
> > 
> > Since you asked, I'll be blunt. This isn't a personal attack on you, Jim,
> > though.
> > 
> > a) Because it fractures the testing and QA processes used by upstream
> > contributors that work on OpenStack projects by requiring them to learn
> > another system -- and one that potentially would require them to understand
> > a whole new surface area for potential bugs
> I don't think there's a large risk of needing to dig deep into mimic,
> and especially twisted. If this does prove to be a problem, I'm happy to
> remove it. However, we can't even explore what it would be like, or how
> hard we would depend on mimic, without mimic being in g-r.
> > b) Because it represents yet another RAX-driven divergence in the QA space.
> > CloudCafe took essentially all of the RAX folks that were at one point
> > working on Tempest and upstream QA and siloed them into a totally different
> > organization, in true RAX fashion. Instead of pulling the OpenStack QA
> > community along together, RAX QA continues to just do its own thing and
> > there's still bitterness on the tips of tongues.
> So, this isn't trying to replace anything. This is adding a different
> way to run functional tests, that is *much* faster than standing up a
> full ironic environment. This is helpful for developers that want to
> quickly run tests before posting them to gerrit, people that need to
> test in constrained environments, etc.

So it won't be used in the gate, just on local developer systems?


> I'm 100% against doing things like Rackspace did with tempest and
> cloudcafe, and I wouldn't be supporting this effort if I felt it was
> similar. Here's how this went:
> * Lekha started working on OnMetal QA, with a goal of doing some amount
>   of upstream work as well.
> * She's previously worked on projects (like autoscale) that interact
>   with OpenStack APIs, and seeing the need to test without a full nova
>   environment, built mimic.
> * In talking with some of the other Ironic folks working on QA (from
>   Intel, IBM, more), she presented mimic as something that may be useful
>   for testing the client (and more). They (and I) agreed it was a neat
>   idea worth trying.
> * Jay offered to help with the global-requirements patch as it's
>   something he's done before, and did the review grinding here.
> * It finally landed, and lifeless asked me to bring up the Twisted
>   conversation on the list. Note that this is not the "is mimic
>   useful" conversation we're having now. Nobody remotely voiced
>   concerns about using a new test tool until this thread happened.
> Please do let me know if any of that seems nefarious; I hope it doesn't.
> > 
> > <snip>
> > 
> > >There was *more* than sufficient time for "I don't think this is useful"
> > >to be posted on the review.
> > 
> > Sorry, this was the first I'd heard of it all.
> > 
> > > If anyone has a hard technical reason why
> > >mimic should not be used to test an OpenStack project, I'm happy to
> > >listen. Otherwise I'd like to work on actually getting things done.
> > 
> > I've listed my hard technical reason: it introduces, IMHO, too large of a
> > surface area for bugs to creep in to the testing process versus the benefit
> > it provides.
> Again, I don't think that's any larger of a surface area than mocks in client
> unit tests being incorrect, and we really won't know whether it causes
> problems in reality.
> // jim

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