Open Stack

Hi all,

Following the approval for Neutron vendor code decomposition
(https://review.openstack.org/#/c/134680/), I just wanted to comment
that it appears to work fine to have an ML2 mechanism driver _entirely_
out of tree, so long as the vendor repository that provides the ML2
mechanism driver does something like this to register their driver as a
neutron.ml2.mechanism_drivers entry point:

  setuptools.setup(
      ...,
      entry_points = {
          ...,
          'neutron.ml2.mechanism_drivers': [
              'calico = xyz.openstack.mech_xyz:XyzMechanismDriver',
          ],
      },
  )

(Please see
https://github.com/Metaswitch/calico/commit/488dcd8a51d7c6a1a2f03789001c2139b16de85c
for the complete change and detail, for the example that works for me.)

Then Neutron and the vendor package can be separately installed, and the
vendor's driver name configured in ml2_conf.ini, and everything works.

Given that, I wonder:

- is that what the architects of the decomposition are expecting?

- other than for the reference OVS driver, are there any reasons in
  principle for keeping _any_ ML2 mechanism driver code in tree?

Many thanks,
     Neil