Remove deprecated external_network_bridge option

[Cedric Brandily]

The l3-agent option external_network_bridge has been deprecated in Liberty[1] because when non-empty the l3-agent ignores network provider properties. It also ensures to handle in the same way internal and external networks.

[1] https://bugs.launchpad.net/neutron/+bug/1491668

[Rossella Sblendido (rossella-o)]

The fix is not simply removing the config entry, since it's the default a migration path is expected. Cedric will add more details :)

[Cedric Brandily (cbrandily)]

Indeed the fix removes the deprecated option and associated code BUT it also removes the default configuration (external_network_bridge non-empty).

It implies to define a migration procedure to transform existing deployments with non-empty external_network_bridge in which :

* the external network is managed directly by neutron-l3-agent,
* router external interface is bound directly on br-ex (OVS case)

into deployments with empty external_network_bridge in which :
* the external network is managed by the L2-agent,
* router external interface is bound on br-int which is bound to br-ex (OVS case)

So such migration implies to :
* ensure l2-agents are able to handle external network "bridges" (=> conf update if needed)
* rewire router external interfaces from br-ex to br-int (OVS case)

IMO, such fix will be done on 2+ releases: a release to introduce the migration tools, a release to remove the deprecated code and the migration tool

[Sean M. Collins (scollins)]

DevStack patch:

https://review.openstack.org/#/c/343072/

[OpenStack Infra (hudson-openstack)]

Related fix proposed to branch: master
Review: https://review.openstack.org/438669

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/438669
Committed: https://git.openstack.org/cgit/openstack/neutron/commit/?id=391ac43bf3862d67cee3ea0f628bd7958e585c7f
Submitter: Jenkins
Branch: master

commit 391ac43bf3862d67cee3ea0f628bd7958e585c7f
Author: Ihar Hrachyshka <email address hidden>
Date: Thu Feb 23 10:21:12 2017 +0000

    Deprecate gateway_external_network_id option

    This option is used only when external_network_bridge is set to
    non-empty value, and that other option is already marked for removal.

    DocImpact The gateway_external_network_id option is deprecated and will
              be removed in next releases.

    Change-Id: Ie6ea9b8977a0e06d69d735532082e9e094c26534
    Related-Bug: #1511578