The public network cannot be identified by df-local-controller

[Li Ma]

2017-01-17 15:48:44.030 6379 ERROR dragonflow.controller.l2_app [-] Physical network public unknown for dragonflow

This message is shown in fullstack job of CI.

For example:
http://logs.openstack.org/02/420602/4/check/gate-dragonflow-dsvm-fullstack-ubuntu-xenial/6521011/logs/screen-df-controller.txt.gz

[Hong Hui Xiao (xiaohhui)]

Since we are only support one external network for now, we can just create/manage it in advance. No need to create and then delete external network every time.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/423786

[Hong Hui Xiao (xiaohhui)]

Since the bridge_mapping will have a default value ['public:br-ex'], the issue has gone with it.

https://github.com/openstack/dragonflow/blob/d692596b5d29c3bc852bfa996e5a5874ff745581/dragonflow/conf/df_provider_networks.py#L23