Both drivers have different approaches when it comes to the metatada
agent, for one the metadata agent for ML2/OVN runs on the compute nodes
(it's distributed) instead of the controller nodes.
The previous default of "<# of CPUs> / 2" did not make sense for ML2/OVN
and if left unchanged could result in scalation problems because of the
number of connections to the OVSDB Southbound database, as seeing in
this email thread for example [0].
This patch puts a placeholder value (None) on the default field of
the "metadata_workers" config by not setting it immediately and then
conditionally set the default value based on each driver:
* ML2/OVS defaults to <# CPUs> // 2, as before.
* ML2/OVN defaults to 2, as suggested in the bug description and also
what's default in TripleO for the OVN driver.
[0]
http://lists.openstack.org/pipermail/openstack-discuss/2020-September/016960.html
Change-Id: I60d5dfef38dc130b47668604c04299b9d23b59b6
Closes-Bug: #1893656
Signed-off-by: Lucas Alvares Gomes <lucasagomes@gmail.com>
f3a8e1547d