[Bug 1904399] Please test proposed package

[Brian Murray]

Hello Lucas, or anyone else affected,

Accepted neutron into focal-proposed. The package will build now and be
available at
https://launchpad.net/ubuntu/+source/neutron/2:16.2.0-0ubuntu3 in a few
hours, and then in the -proposed repository.

Please help us by testing this new package.  See
https://wiki.ubuntu.com/Testing/EnableProposed for documentation on how
to enable and use -proposed.  Your feedback will aid us getting this
update out to other Ubuntu users.

If this package fixes the bug for you, please add a comment to this bug,
mentioning the version of the package you tested, what testing has been
performed on the package and change the tag from verification-needed-
focal to verification-done-focal. If it does not fix the bug for you,
please add a comment stating that, and change the tag to verification-
failed-focal. In either case, without details of your testing we will
not be able to proceed.

Further information regarding the verification process can be found at
https://wiki.ubuntu.com/QATeam/PerformingSRUVerification .  Thank you in
advance for helping!

N.B. The updated package will be released to -updates after the bug(s)
fixed by this package have been verified and the package has been in
-proposed for a minimum of 7 days.

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https://bugs.launchpad.net/bugs/1904399

Title:
  [OVN] Inconsistent "flooding to unregistered" IGMP configuration

Status in Ubuntu Cloud Archive:
  Triaged
Status in Ubuntu Cloud Archive ussuri series:
  Triaged
Status in Ubuntu Cloud Archive victoria series:
  Triaged
Status in neutron:
  Fix Released
Status in neutron package in Ubuntu:
  Fix Released
Status in neutron source package in Focal:
  Fix Committed
Status in neutron source package in Groovy:
  Fix Committed
Status in neutron source package in Hirsute:
  Fix Released

Bug description:
  ML2/OVN reuses the same "[ovs]/igmp_snooping_enable" configuration
  option from ML2/OVS, which says [0]:

  "Setting this option to True will also enable Open vSwitch mcast-
  snooping-disable-flood-unregistered flag. This option will disable
  flooding of unregistered multicast packets to all ports."

  But, that's not true for ML2/OVN, in fact, this is the opposite
  because ML2/OVN does have the option to flood to unregistered VMs
  enabled by default.

  In order to keep the consistent between both drivers and this
  configuration option, ML2/OVN needs to disable the
  "mcast_flood_unregistered" configuration in the other_config column
  from the Logical Switch table when igmp_snooping_enable is True.

  [0]
  https://opendev.org/openstack/neutron/src/branch/master/neutron/conf/agent/ovs_conf.py#L36-L47

  [Impact]

  See above.

  [Test Case]

  Run the following and expect success:
  root at f1:~# sudo apt install python3-neutron
  root at f1:/usr/lib/python3/dist-packages# python3 -m unittest neutron.tests.unit.plugins.ml2.drivers.ovn.mech_driver.ovsdb.test_maintenance.TestDBInconsistenciesPeriodics.test_check_for_igmp_snoop_support

  I would also like to get test feedback from Canonical bootstack as
  they are hitting this issue.

  [Regression Potential]
  This is a very minimal and targeted change that always hard codes MCAST_FLOOD_UNREGISTERED to 'false'.

  In assessing regression potential for changes like this, one that
  comes to mind is potential of a type error when setting
  MCAST_FLOOD_UNREGISTERED. Upon visual inspection of this code fix, a
  type error would be impossible, as what was once set to a 'true' or
  'false' value is now set to 'false'.

  Another thought is whether MCAST_FLOOD_UNREGISTERED has any use if
  MCAST_SNOOP is set to false, but that is not the case according to
  upstream OVN documentation which states: mcast_flood_unregistered:
  optional string, either true or false Determines whether unregistered
  multicast traffic should be flooded or not. Only applicable if
  other_config:mcast_snoop is enabled.

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