dhcp agent crashes when deleting network if bulk reload enabled

[Boyvinall]

If DHCP bulk reload is enabled, I get the following crash in the bulk reload loop when deleting a network:

Running command: 'neutron-dhcp-agent --config-file /etc/neutron/neutron.conf --config-file /etc/neutron/dhcp_agent.ini'
+ exec neutron-dhcp-agent --config-file /etc/neutron/neutron.conf --config-file /etc/neutron/dhcp_agent.ini
Traceback (most recent call last):
  File "/usr/lib/python3.6/site-packages/eventlet/hubs/hub.py", line 461, in fire_timers
    timer()
  File "/usr/lib/python3.6/site-packages/eventlet/hubs/timer.py", line 59, in __call__
    cb(*args, **kw)
  File "/usr/lib/python3.6/site-packages/neutron/agent/dhcp/agent.py", line 161, in _reload_bulk_allocations
    self.call_driver('bulk_reload_allocations', network)
  File "/usr/lib/python3.6/site-packages/osprofiler/profiler.py", line 160, in wrapper
    result = f(*args, **kwargs)
  File "/usr/lib/python3.6/site-packages/neutron/agent/dhcp/agent.py", line 167, in call_driver
    {'net': network.id, 'action': action})
AttributeError: 'NoneType' object has no attribute 'id'
+ sudo -E kolla_set_configs

Line numbers might differ slightly due to my patch for https://bugs.launchpad.net/neutron/+bug/1886969 but the issue is present without my change.

[Boyvinall (boyvinall)]

I'm not yet sure if this happens every time, I'll be doing some more testing on this over the next few days.

[Rodolfo Alonso (rodolfo-alonso-hernandez)]

For any other reviewer, please read https://bugs.launchpad.net/neutron/+bug/1886969. Both bugs are related.

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.opendev.org/742363
Committed: https://git.openstack.org/cgit/openstack/neutron/commit/?id=20b138ff3118029e86f0525695160c4c7ca8b551
Submitter: Zuul
Branch: master

commit 20b138ff3118029e86f0525695160c4c7ca8b551
Author: Matt Vinall <email address hidden>
Date: Thu Jul 9 21:08:21 2020 +0100

    fix dhcp bulk reload exceptions

    1886969 - The bulk reload code was written for python2 and caused
    an exception running under python3. This change works under python3.

    1890027 - There was an additional exception triggered when
    deleting networks - reading the network from the cache returned 'None'
    and this was not properly checked before use.

    Change-Id: I4e546c0e37146b1f34d8b5e6637c407b0c04ad4d
    Closes-Bug: 1886969
    Closes-Bug: 1890027
    Signed-off-by: Matt Vinall <email address hidden>

[OpenStack Infra (hudson-openstack)]

This issue was fixed in the openstack/neutron 16.3.0 release.

[OpenStack Infra (hudson-openstack)]

This issue was fixed in the openstack/neutron 17.1.0 release.

[OpenStack Infra (hudson-openstack)]

This issue was fixed in the openstack/neutron 18.0.0.0rc1 release candidate.