Change [1] removed the deprecated option external_network_bridge. Per
commit message in change [2], "l3 agent can handle any networks by
setting the neutron parameter external_network_bridge and
gateway_external_network_id to empty". So the consequence of [1] was to
introduce a regression whereby multiple external networks are not
supported by the L3 agent anymore.
This change proposes a new simplified rule. If
gateway_external_network_id is defined, that is the network that the L3
agent will use. If not and multiple external networks exist, the L3
agent will handle any of them.
[1] https://review.opendev.org/#/c/567369/
[2] https://review.opendev.org/#/c/59359
Change-Id: Idd766bd069eda85ab6876a78b8b050ee5ab66cf6
Closes-Bug: #1824571
(cherry picked from commit 0b3f5f429d)
62e0bee820