Deletion of Lbaas-listener is successfull even when it is part of Lbaas pool

[varun kumar yadav]

Description ->Deletion of loadbalancer listener is successfull even when it is attached to Lbaas pool. After deletion of listener when user creates a new listener neutron Cli command do not support addition of new listener in existing lbaas pool.

User impact of deletion-> loadbalancer stops working if user able to delete listener accidentally

Step to reproduce the scenario->

neutron lbaas-loadbalancer-create --name lb-15 public-subnet
neutron lbaas-listener-create --name listener-15-1 --loadbalancer lb-15 --protocol HTTP --protocol-port 80 --connection-limit 1
neutron lbaas-pool-create --name pool-15 --lb-algorithm ROUND_ROBIN --listener listener-15-1 --protocol HTTP
neutron lbaas-healthmonitor-create --name health-15 --delay 5 --max-retries 4 --timeout 3 --type PING --pool pool-15
neutron lbaas-listener-delete <listener-id>

create a listener again and try to add to existing pool no cli support this operation as well as no Horizon support for the same

Expected output-> Two approach to look for.

1. If deletion of listener is possible then addition of listener should also be allowed.

2. Another option is if listener is mandatory field for pool creation then like other field lbaaS listener deletion should throw an error.

version of openstack -> stable stein
linux ubuntu -> 18.04

Reason why it is needed:(while creation of listener is mandatory for a pool then deletion also should not be allowed without deleting pool).
 root@vmware:~/vio6.0# neutron lbaas-pool-create --name lb-pool2 --lb-algorithm ROUND_ROBIN --protocol HTTP --insecure
neutron CLI is deprecated and will be removed in the future. Use openstack CLI instead.
/usr/local/lib/python2.7/dist-packages/urllib3/connectionpool.py:857: InsecureRequestWarning: Unverified HTTPS request is being made. Adding certificate verification is strongly advised. See: https://urllib3.readthedocs.io/en/latest/advanced-usage.html#ssl-warnings
  InsecureRequestWarning)
/usr/local/lib/python2.7/dist-packages/urllib3/connectionpool.py:857: InsecureRequestWarning: Unverified HTTPS request is being made. Adding certificate verification is strongly advised. See: https://urllib3.readthedocs.io/en/latest/advanced-usage.html#ssl-warnings
  InsecureRequestWarning)
At least one of --listener or --loadbalancer must be specified.

[Michael Johnson (johnsom)]

neutron-lbaas is not a neutron project. This patch has been moved to the neutron-lbaas storyboard in story: https://storyboard.openstack.org/#!/story/2005827