Open Stack

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> I was (rightfully) asked to share my comments on the matter that I
> left in gerrit here. See below.
> 
> On 12/12/14 22:40, Sean Dague wrote:
> > On 12/12/2014 01:05 PM, Maru Newby wrote:
> >> 
> >> On Dec 11, 2014, at 2:27 PM, Sean Dague <sean at dague.net> wrote:
> >> 
> >>> On 12/11/2014 04:16 PM, Jay Pipes wrote:
> >>>> On 12/11/2014 04:07 PM, Vishvananda Ishaya wrote:
> >>>>> On Dec 11, 2014, at 1:04 PM, Jay Pipes <jaypipes at gmail.com>
> >>>>> wrote:
> >>>>>> On 12/11/2014 04:01 PM, Vishvananda Ishaya wrote:
> >>>>>>> 
> >>>>>>> On Dec 11, 2014, at 8:00 AM, Henry Gessau
> >>>>>>> <gessau at cisco.com> wrote:
> >>>>>>> 
> >>>>>>>> On Thu, Dec 11, 2014, Mark McClain <mark at mcclain.xyz>
> >>>>>>>> wrote:
> >>>>>>>>> 
> >>>>>>>>>> On Dec 11, 2014, at 8:43 AM, Jay Pipes
> >>>>>>>>>> <jaypipes at gmail.com <mailto:jaypipes at gmail.com>>
> >>>>>>>>>> wrote:
> >>>>>>>>>> 
> >>>>>>>>>> I'm generally in favor of making name attributes
> >>>>>>>>>> opaque, utf-8 strings that are entirely
> >>>>>>>>>> user-defined and have no constraints on them. I
> >>>>>>>>>> consider the name to be just a tag that the user
> >>>>>>>>>> places on some resource. It is the resource's ID
> >>>>>>>>>> that is unique.
> >>>>>>>>>> 
> >>>>>>>>>> I do realize that Nova takes a different approach
> >>>>>>>>>> to *some* resources, including the security group
> >>>>>>>>>> name.
> >>>>>>>>>> 
> >>>>>>>>>> End of the day, it's probably just a personal
> >>>>>>>>>> preference whether names should be unique to a
> >>>>>>>>>> tenant/user or not.
> >>>>>>>>>> 
> >>>>>>>>>> Maru had asked me my opinion on whether names
> >>>>>>>>>> should be unique and I answered my personal
> >>>>>>>>>> opinion that no, they should not be, and if
> >>>>>>>>>> Neutron needed to ensure that there was one and
> >>>>>>>>>> only one default security group for a tenant,
> >>>>>>>>>> that a way to accomplish such a thing in a
> >>>>>>>>>> race-free way, without use of SELECT FOR UPDATE,
> >>>>>>>>>> was to use the approach I put into the pastebin
> >>>>>>>>>> on the review above.
> >>>>>>>>>> 
> >>>>>>>>> 
> >>>>>>>>> I agree with Jay.  We should not care about how a
> >>>>>>>>> user names the resource. There other ways to
> >>>>>>>>> prevent this race and Jay’s suggestion is a good
> >>>>>>>>> one.
> >>>>>>>> 
> >>>>>>>> However we should open a bug against Horizon because
> >>>>>>>> the user experience there is terrible with duplicate
> >>>>>>>> security group names.
> >>>>>>> 
> >>>>>>> The reason security group names are unique is that the
> >>>>>>> ec2 api supports source rule specifications by
> >>>>>>> tenant_id (user_id in amazon) and name, so not
> >>>>>>> enforcing uniqueness means that invocation in the ec2
> >>>>>>> api will either fail or be non-deterministic in some
> >>>>>>> way.
> >>>>>> 
> >>>>>> So we should couple our API evolution to EC2 API then?
> >>>>>> 
> >>>>>> -jay
> >>>>> 
> >>>>> No I was just pointing out the historical reason for
> >>>>> uniqueness, and hopefully encouraging someone to find the
> >>>>> best behavior for the ec2 api if we are going to keep the
> >>>>> incompatibility there. Also I personally feel the ux is
> >>>>> better with unique names, but it is only a slight
> >>>>> preference.
> >>>> 
> >>>> Sorry for snapping, you made a fair point.
> >>> 
> >>> Yeh, honestly, I agree with Vish. I do feel that the UX of
> >>> that constraint is useful. Otherwise you get into having to
> >>> show people UUIDs in a lot more places. While those are good
> >>> for consistency, they are kind of terrible to show to people.
> >> 
> >> While there is a good case for the UX of unique names - it also
> >> makes orchestration via tools like puppet a heck of a lot simpler
> >> - the fact is that most OpenStack resources do not require unique
> >> names.  That being the case, why would we want security groups to
> >> deviate from this convention?
> > 
> > Maybe the other ones are the broken ones?
> > 
> > Honestly, any sanely usable system makes names unique inside a
> > container. Like files in a directory.
> 
> Correct. Or take git: it does not use hashes to identify objects, right?
> 
> > In this case the tenant is the container, which makes sense.
> > 
> > It is one of many places that OpenStack is not consistent. But I'd
> > rather make things consistent and more usable than consistent and
> > less.
> 
> Are we only proposing to make security group name unique? I assume
> that, since that's what we currently have in review. The change would
> make API *more* inconsistent, not less, since other objects still use
> uuid for identification.
> 
> You may say that we should move *all* neutron objects to the new
> identification system by name. But what's the real benefit?
> 
> If there are problems in UX (client, horizon, ...), we should fix the
> view and not data models used. If we decide we want users to avoid
> using objects with the same names, fine, let's add warnings in UI
> (probably with an option to disable it so that we don't push the
> validation into their throats).
> 
> Finally, I have concern about us changing user visible object
> attributes like names during db migrations, as it's proposed in the
> patch discussed here. I think such behaviour can be quite unexpected
> for some users, if not breaking their workflow and/or scripts.
> 
> My belief is that responsible upstream does not apply ad-hoc changes
> to API to fix a race condition that is easily solvable in other ways
> (see Assaf's proposal to introduce a new DefaultSecurityGroups table
> in patchset 12 comments).
> 

As usual you explain yourself better than I can... I think my main
original objection to the patch is that it feels like an accidental
API change to fix a bug. If you want unique naming:
1) We need to be consistent across different resources
2) It needs to be in a dedicate change, and perhaps blueprint

Since there's conceivable alternative solutions to the bug that aren't
substantially more costly or complicated, I don't see why we would pursue
the proposed approach.

> As for the whole object identification scheme change, for this to
> work, it probably needs a spec and a long discussion on any possible
> complications (and benefits) when applying a change like that.
> 
> For reference and convenience of readers, leaving the link to the
> patch below: https://review.openstack.org/#/c/135006/
> 
> 
> 
> > 
> > -Sean
> > 
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