nb db migration

The following error can be observed when restart df-local-controller after updating code recently. It is because the a new field name unique_key was added to lswitch[1] recently. However, old data in nb db will not have such field, because the old data was created before the code.

The workaround might be re-create all data in nb db, which is not a good way for a legacy user. A feasible fix will be adding unique_key to lswitch when found it is missing, other feasible fix might be provide script to update the nb db.

[1] https://review.openstack.org/#/c/394017/

2016-11-23 15:14:33.231 ERROR dragonflow.controller.dispatcher [-] Dragonflow application 'DHCPApp' failed in update_logical_switch
2016-11-23 15:14:33.231 TRACE dragonflow.controller.dispatcher Traceback (most recent call last):
2016-11-23 15:14:33.231 TRACE dragonflow.controller.dispatcher File "/opt/stack/dragonflow/dragonflow/controller/dispatcher.py", line 46, in dispatch
2016-11-23 15:14:33.231 TRACE dragonflow.controller.dispatcher handler(*args, **kwargs)
2016-11-23 15:14:33.231 TRACE dragonflow.controller.dispatcher File "/opt/stack/dragonflow/dragonflow/controller/dhcp_app.py", line 454, in update_logical_switch
2016-11-23 15:14:33.231 TRACE dragonflow.controller.dispatcher self._install_dhcp_unicast_match_flow(dhcp_ip, network_id)
2016-11-23 15:14:33.231 TRACE dragonflow.controller.dispatcher File "/opt/stack/dragonflow/dragonflow/controller/dhcp_app.py", line 512, in _install_dhcp_unicast_match_flow
2016-11-23 15:14:33.231 TRACE dragonflow.controller.dispatcher const.DHCP_TABLE, match=match)
2016-11-23 15:14:33.231 TRACE dragonflow.controller.dispatcher File "/opt/stack/dragonflow/dragonflow/controller/df_base_app.py", line 58, in add_flow_go_to_table
2016-11-23 15:14:33.231 TRACE dragonflow.controller.dispatcher priority=priority, match=match)
2016-11-23 15:14:33.231 TRACE dragonflow.controller.dispatcher File "/opt/stack/dragonflow/dragonflow/controller/df_base_app.py", line 99, in mod_flow
2016-11-23 15:14:33.231 TRACE dragonflow.controller.dispatcher datapath.send_msg(message)
2016-11-23 15:14:33.231 TRACE dragonflow.controller.dispatcher File "/usr/lib/python2.7/site-packages/ryu/controller/controller.py", line 344, in send_msg
2016-11-23 15:14:33.231 TRACE dragonflow.controller.dispatcher msg.serialize()
2016-11-23 15:14:33.231 TRACE dragonflow.controller.dispatcher File "/usr/lib/python2.7/site-packages/ryu/ofproto/ofproto_parser.py", line 211, in serialize
2016-11-23 15:14:33.231 TRACE dragonflow.controller.dispatcher self._serialize_body()
2016-11-23 15:14:33.231 TRACE dragonflow.controller.dispatcher File "/usr/lib/python2.7/site-packages/ryu/ofproto/ofproto_v1_3_parser.py", line 2679, in _serialize_body
2016-11-23 15:14:33.231 TRACE dragonflow.controller.dispatcher match_len = self.match.serialize(self.buf, offset)
2016-11-23 15:14:33.231 TRACE dragonflow.controller.dispatcher File "/usr/lib/python2.7/site-packages/ryu/ofproto/ofproto_v1_3_parser.py", line 1011, in serialize
2016-11-23 15:14:33.231 TRACE dragonflow.controller.dispatcher field_offset)
2016-11-23 15:14:33.231 TRACE dragonflow.controller.dispatcher File "/usr/lib/python2.7/site-packages/ryu/ofproto/oxx_fields.py", line 250, in _serialize
2016-11-23 15:14:33.231 TRACE dragonflow.controller.dispatcher value_len = len(value)
2016-11-23 15:14:33.231 TRACE dragonflow.controller.dispatcher TypeError: object of type 'NoneType' has no len()