On 2015/12/14 14:52, Kevin Benton wrote:
I see, so regular users are supposed to use this information as well.
But how are they supposed to use it? For example, if they see that
their network has availability zones 1 and 4, but their instance is
hosted in zone 3, what are they supposed to do?
I don't think that there is what they should do in the case because
Neutron AZ is different from Nova AZ. For example, there may be a case
like the following.
1. User throws POST Network API and Subnet API with
availability_zone_hints [AZ1, AZ2]
2. Neutron server tries to schedule the resource on both AZ1 and AZ2 but
the resource are scheduled on AZ1 only by some reasons
3. User confirms via GET Network API where his resource is hosted and he
knows it's AZ1 only
4. User also can know AZ is ready via GET Availability zones API: AZ1, AZ3
5. User deletes previous resource and he recreates his resource with
availability_zone_hints [AZ1, AZ3]
On Sun, Dec 13, 2015 at 8:57 PM, Hirofumi Ichihara
<ichihara.hirof...@lab.ntt.co.jp
<mailto:ichihara.hirof...@lab.ntt.co.jp>> wrote:
Hi Kevin,
On 2015/12/14 11:10, Kevin Benton wrote:
Hi all,
The availability zone code added a new field to the network API
that shows the availability zones of a network. This caused a
pretty big performance impact to get_networks calls because it
resulted in a database lookup for every network.[1]
I already put a patch up to join the information ahead of time in
the network model.[2]
I agree with your suggestion. I believe that the patch can solve
the performance issue.
However, before we go forward with that, I think we should
consider the removal of that field from the API.
Having to always join to the DHCP agents table to lookup which
zones a network has DHCP agents on is expensive and is
duplicating information available with other API calls.
Additionally, the field is just called 'availability_zones' but
it's being derived solely from AZ definitions in DHCP agent
bindings for that network. To me that doesn't represent where the
network is available, it just says which zones its scheduled DHCP
instances live in. If that's the purpose, then we should just be
using the DHCP agent API for this info and not impact the network
API.
I don't think so. I have three points.
1. Availability zone is implemented in just a case with Agent now,
but it's reference implementation. For example, we should expect
that availability zone will be used by plugin without agent.
2. In users view, availability zone is related to network
resource. On the other hand, users doesn't need to consider Agent
or operators doesn't like to enable users to do in the first
place. So I don't agree with using Agent API.
3. We should consider whether users want to know the field.
Originally, the field doesn't exist in Spec[3] but I added it
according with reviewer's opinion(maybe Akihiro?). This is about
discussion of use case. After users create resources via API with
availability_zone_hints so that they achieve HA for their service,
they want to know which zones are their resources hosted on
because their resources might not be distributed on multiple
availability zones by any reasons. In the case, they need to know
"availability_zones" for the resources via Network API.
Thanks,
Hirofumi
[3]: https://review.openstack.org/#/c/169612/31
Thoughts?
1. https://bugs.launchpad.net/neutron/+bug/1525740
2. https://review.openstack.org/#/c/257086/
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Kevin Benton
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