[openstack-dev] [Neutron] UniqueConstraint for name and tenant_id in security group

Sean Dague sean at dague.net
Fri Dec 12 21:40:32 UTC 2014

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. 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.


Sean Dague

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