When remove l2gw connection, can not remove vlan binding in neutron db when binding vlan is zero

[fanghuilin]

When remove l2gw connection, can not remove vlan binding in neutron db when binding vlan is zero. And then, it cannot
create this l2gw connection again.

Step1: At first, no l2gw connection exist

# openstack l2gw list
+--------------------------------------+----------------------------------+------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| ID | Tenant | Name | Devices |
+--------------------------------------+----------------------------------+------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| 67eb8390-8cc8-409a-85fd-282e05e59758 | 02c0f9589cca400abd623868516c209b | gw1 | device_name='WAI-4_3_617-H68-10.160.9.161.lyct', id='c875d2c4-494d-41f1-a992-1956a6ff6048', interfaces='[{u'segmentation_id': [], u'name': u'Ten-GigabitEthernet1/0/42'}]' |
+--------------------------------------+----------------------------------+------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------+

# openstack l2gw connection list

Step2: create l2gw connection
# openstack l2gw connection create --default-segmentation-id 0 gw1 fhl-self-network
+-----------------+--------------------------------------+
| Field | Value |
+-----------------+--------------------------------------+
| ID | 5f221b47-13c4-4282-8abd-b3e9a222bb69 |
| L2 GateWay ID | 67eb8390-8cc8-409a-85fd-282e05e59758 |
| Network ID | 318ee112-4254-4139-abed-b51125a3fe29 |
| Segmentation ID | 0 |
| Tenant | 02c0f9589cca400abd623868516c209b |
+-----------------+--------------------------------------+

Step3: Get info from neutron db
logical_switches
+--------------------------------------+--------------------------------------+------+------------------+
| uuid | name | key | ovsdb_identifier |
+--------------------------------------+--------------------------------------+------+------------------+
| b17aab90-6871-44eb-85ac-7e60bbdcc6d5 | 318ee112-4254-4139-abed-b51125a3fe29 | 5 | ovsdb1 |

vlan_bindings
+--------------------------------------+------+--------------------------------------+------------------+
| port_uuid | vlan | logical_switch_uuid | ovsdb_identifier |
+--------------------------------------+------+--------------------------------------+------------------+
| f38b77ec-a928-4b04-aed1-ec7d1c587b8c | 0 | b17aab90-6871-44eb-85ac-7e60bbdcc6d5 | ovsdb1 |
+--------------------------------------+------+--------------------------------------+------------------+

Step4: delete l2gw connection
# openstack l2gw connection delete 5f221b47-13c4-4282-8abd-b3e9a222bb69
L2 Gateaway Connection 5f221b47-13c4-4282-8abd-b3e9a222bb69 deleted

Step5: Get info from neutron db, there have vlan bindings info left over
logical_switches
+--------------------------------------+--------------------------------------+------+------------------+
| uuid | name | key | ovsdb_identifier |
+--------------------------------------+--------------------------------------+------+------------------+
| b17aab90-6871-44eb-85ac-7e60bbdcc6d5 | 318ee112-4254-4139-abed-b51125a3fe29 | 5 | ovsdb1 |

vlan_bindings
+--------------------------------------+------+--------------------------------------+------------------+
| port_uuid | vlan | logical_switch_uuid | ovsdb_identifier |
+--------------------------------------+------+--------------------------------------+------------------+
| f38b77ec-a928-4b04-aed1-ec7d1c587b8c | 0 | b17aab90-6871-44eb-85ac-7e60bbdcc6d5 | ovsdb1 |
+--------------------------------------+------+--------------------------------------+------------------+

Step6: create l2gw connection again, it cannot create.
# openstack l2gw connection create --default-segmentation-id 0 gw1 fhl-self-network
Duplicate segmentation ID for the interface name=Ten-GigabitEthernet1/0/42 uuid=f38b77ec-a928-4b04-aed1-ec7d1c587b8c
Neutron server returns request_ids: ['req-23c19d6c-4c8c-4ffb-acb6-d618139bd366']

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.opendev.org/735285

[Lajos Katona (lajos-katona)]

Thank you for the bug report, I check it this week.

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.opendev.org/735285
Committed: https://git.openstack.org/cgit/openstack/networking-l2gw/commit/?id=0c22e5ab19ed0203e3f517341f550e6b01905676
Submitter: Zuul
Branch: master

commit 0c22e5ab19ed0203e3f517341f550e6b01905676
Author: fanghuilin <[e-mail]>
Date: Fri Jun 12 11:59:29 2020 +0800

    Fix cleaning vlan_bindings in neutron db when vlan is 0.

    Change-Id: I115f777d3e990587a58ce97a61f59b3480e9270b
    Closes-bug: #1883203