DB out of sync

Adding the following exception:

diff --git a/networking_l2gw/db/l2gateway/l2gateway_db.py b/networking_l2gw/db/l2gateway/l2gateway_db.py
index 806647b..227d5d5 100644
--- a/networking_l2gw/db/l2gateway/l2gateway_db.py
+++ b/networking_l2gw/db/l2gateway/l2gateway_db.py
@@ -277,6 +277,7 @@ class L2GatewayMixin(l2gateway.L2GatewayPluginBase,

     def create_l2_gateway_connection(self, context, l2_gateway_connection):
         """Create l2 gateway connection."""
+ raise Exception("GET OUT OF SYNC!")
         gw_connection = l2_gateway_connection[self.connection_resource]
         l2_gw_id = gw_connection.get('l2_gateway_id')
         network_id = gw_connection.get('network_id')

This will trigger the inconsistency between the DB and the OVSDB of the managed switch:

centos@devstack ~]$ ./l2gw_create.txt
neutron CLI is deprecated and will be removed in the future. Use openstack CLI instead.
Request Failed: internal server error while processing your request.
Neutron server returns request_ids: ['req-79016e1e-9c9a-44f8-9186-ebc5ceda8039']
neutron CLI is deprecated and will be removed in the future. Use openstack CLI instead.
Request Failed: internal server error while processing your request.
Neutron server returns request_ids: ['req-fef00891-1477-462a-be44-df068a5989ab']

[centos@devstack ~]$ cat l2gw_create.txt
 neutron l2-gateway-connection-create gw1 private --default-segmentation-id 200
 neutron l2-gateway-connection-create gw1 private2 --default-segmentation-id 300
[centos@devstack ~]$ neutron l2-gateway-connection-list
neutron CLI is deprecated and will be removed in the future. Use openstack CLI instead.

[centos@devstack ~]$

However, the OVSDB has been modified adding new vlan bindings:

[centos@hwvtep ~]$ sudo ovsdb-client dump hardware_vtep [35/8267]
ACL table
_uuid acl_entries acl_fault_status acl_name
----- ----------- ---------------- --------

ACL_entry table
_uuid acle_fault_status action dest_ip dest_mac dest_mask dest_port_max dest_port_min direction ethertype icmp_code icmp_type protocol sequence source_ip source_mac source_mask source_port_max source_port_m
in tcp_flags tcp_flags_mask
----- ----------------- ------ ------- -------- --------- ------------- ------------- --------- --------- --------- --------- -------- -------- --------- ---------- ----------- --------------- -------------
-- --------- --------------

Arp_Sources_Local table
_uuid locator src_mac
----- ------- -------

Arp_Sources_Remote table
_uuid locator src_mac
----- ------- -------

Global table
_uuid managers switches
------------------------------------ -------------------------------------- --------------------------------------
0d30fbd3-e040-47c0-9841-c011baa554c3 [6f32515f-59bf-44ae-b12a-43255d2019b9] [1a412a01-943e-47fb-9779-d631d4df4e2a]

Logical_Binding_Stats table
_uuid bytes_from_local bytes_to_local packets_from_local packets_to_local
----- ---------------- -------------- ------------------ ------------...

A possible way to repair it would be to use an synchronizer using external uuids in the OVSDB. For example, if we use the "description" field in the Physical_port table to store Neutron L2Gateway Connection UUID:

[centos@hwvtep ~]$ sudo vtep-ctl list Physical_port
_uuid : d53ee688-e763-4165-acc4-134acf447f50
acl_bindings : {}
description : ""
name : "eth2"
port_fault_status : []
vlan_bindings : {200=f5760373-6242-4b9d-ab70-e09b3eb7ad92, 300=adc60ecd-3c46-477e-ad47-f6cedb382234}
vlan_stats : {}

_uuid : 77c6c08f-1520-4698-8808-abd4f7eeb61b
acl_bindings : {}
description : "9cd3ad7d-71aa-498e-8ce8-befac2ad95fc"
name : "eth1"
port_fault_status : []
vlan_bindings : {200=f5760373-6242-4b9d-ab70-e09b3eb7ad92, 300=adc60ecd-3c46-477e-ad47-f6cedb382234}
vlan_stats : {}

neutron CLI is deprecated and will be removed in the future. Use openstack CLI instead.
Created a new l2_gateway_connection:
+-----------------+--------------------------------------+
| Field | Value |
+-----------------+--------------------------------------+
| id | 9cd3ad7d-71aa-498e-8ce8-befac2ad95fc |----------> Check in the table above
| l2_gateway_id | 8196df15-c9f0-4f3f-b4a4-2377f2505ebe |
| network_id | 0f8f9ccd-a85a-4d7e-b71e-1df65b90f18e |
| segmentation_id | 200 |
| tenant_id | 802531e233854bffbac67504eaed1cd3 |
+-----------------+--------------------------------------+

If there is an orphan object, we could apply changes to solve this inconsistency.