Missing support for AGENT.availability_zone

[Florian Guitton]

Hello everybody,

Currently there does not seem to be a way to control the neutron availability_zone of a compute node. When relying on DVR_SNAT this is an issue because compute nodes do not bring up the necessary routers to perform network communication. Currently all node deployed with this charm have default 'nova' availability zone.

I am missing something ? Is there a way to work around this issue ?

[Alex Kavanagh (ajkavanagh)]

TRIAGE:

The [agent] -> availability_zone isn't set in the neutron-api's neutron.conf which is where it would need to be supported.

[Dmitrii Shcherbakov (dmitriis)]

I think I already fixed this last year.

https://bugs.launchpad.net/charm-nova-compute/+bug/1796068

`customize-failure-domain = True` set on charm-nova-compute will propagate JUJU_AVAILABILITY_ZONE environment variable set by a unit agent in a hook context to charm-neutron-openvswitch.

One needs to set availability zones for machines in the underlying provider for JUJU_AVAILABILITY_ZONE to be populated.

The availability zone config needs to be set only for neutron agents (l3, dhcp):

➜ neutron git:(stable/queens) ✗ grep -RiP "'availability_zone'" | grep cfg.
neutron/conf/agent/common.py: cfg.StrOpt('availability_zone', max_length=255, default='nova',

customize-failure-domain is set to "false" by default on nova-compute.

[Alex Kavanagh (ajkavanagh)]

Hi Dima

I think the original bug poster is talking about this setting:

https://docs.openstack.org/neutron/stein/configuration/neutron.html#agent.availability_zone

which may/may not be the same as the default_availability_zone, but I'm not sure. The above setting is placed in neutron.conf, which I believe, in CDO speak, is in neutron-api. Perhaps other settings, that you've described above, work with, or override this setting?

Thanks.

[Florian Guitton (f-guitton)]

Hello,

In our experiment, setting the default-availability-zone of nova-compute would effectively set the nova availability zone to the expected value, but it has no effect on the neutron-openvswitch configuration.

Nova and Neutron availability zones implementation are non correlated and neither should they always be tied to the underlying juju zoning.

In our scenario, Juju understands zones are a rack related concept, whereas neutron zones are datacentre related and nova zones are defined in conjunction with host aggregates to create domain/tenant related server groups.

In the context where multiple neutron-gateway might be deployed with different default-availability-zone, the related neutron-openvswitch charm should probably inherit it from the relationship independently of nova.

Best wishes,

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.opendev.org/684746
Committed: https://git.openstack.org/cgit/openstack/charm-neutron-openvswitch/commit/?id=85b1a9656ab5d796af63fc2f3ed5ae6c9d2f108e
Submitter: Zuul
Branch: master

commit 85b1a9656ab5d796af63fc2f3ed5ae6c9d2f108e
Author: James Page <email address hidden>
Date: Wed Sep 25 14:07:03 2019 +0100

    Ensure availability_zone set globally for agents

    Inline with the neutron-gateway charm, move availability_zone
    configuration to the neutron.conf configuration file to ensure
    that its set consistently for all neutron agents that may be
    running on the unit.

    Change-Id: If9438302f8f889a1cbaf93f8a460e190e551241b
    Closes-Bug: 1829537