[openstack-dev] Listing regions and availability zones - Doesn't this belong in Keystone?

George Reese george.reese at imaginary.com
Fri Jan 18 16:14:29 UTC 2013


On Jan 18, 2013, at 10:10 AM, Jay Pipes <jaypipes at gmail.com> wrote:

> A couple folks have recently brought up why there isn't any ability in
> Nova to list the availability zones and show the AZ and region for an
> instance.
> Phil Day shared the related blueprint [1] which led me to investigate
> one of the patches proposed for the blueprint for listing availability
> zones:
> https://review.openstack.org/#/c/19824/
> I'd like to bring up a point that I think is important to address before
> such a patch is accepted.
> Why is the listing of availability zones or regions an operation in Nova
> at all? This information more naturally belongs in Keystone.
> Many installations of Nova (including ours) do not use one giant Nova
> database that stores data for instances in multiple availability zones.
> To scale more effectively, we have a single Nova database for one
> availability zone in a region.
> On the other hand, we have a singular Keystone database cluster that
> stores catalog information for more than one availability zone and more
> than one region. We do this to enable a unified authentication model
> across regions and AZs.
> IMHO, it makes more sense to put operations for listing AZs and regions
> into Keystone since:
> a) Keystone already has natural interfaces for returning service
> catalogs. Listing availability zones (and further, regions) is a natural
> extension of the service catalog.
> b) Availability zones and regions apply to more than just Nova. At a
> minimum, volumes in Cinder are assigned in an availability zone.
> Keystone advertises more endpoints than just Nova, so again it seems
> more natural to have Keystone advertise the availability zones and
> regions a tenant has access to.
> Thoughts?
> -jay
> [1] https://blueprints.launchpad.net/nova/+spec/show-availability-zone
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George Reese (george.reese at imaginary.com)
t: @GeorgeReese               m: +1(207)956-0217               Skype: nspollution

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