Add IP remove warnings for VRF commands

[hamnarauf]

What I did

Added IP address remove warnings when performing various VRF commands i.e.,
- vrf bind
- vrf unbind
- del vrf

How I did it

• Modify config/main.py to include click.echo warnings.
• Add test cases for interface/subinterface vrf bind, unbind and del.

How to verify it

Tested the changes locally by building sonic-utilities Python wheel package inside Bullseye slave container

mdanish@3be53d98ab67:/sonic/src/sonic-utilities$ pytest-3 tests/show_vrf_test.py
==================================================================== test session starts =====================================================================
platform linux -- Python 3.9.2, pytest-6.0.2, py-1.10.0, pluggy-0.13.0
rootdir: /sonic/src/sonic-utilities/tests, configfile: pytest.ini
plugins: pyfakefs-5.0.0, cov-2.10.1
collected 3 items                                                                                                                                            

tests/show_vrf_test.py ....                                                                                                                            [100%]

===================================================================== 3 passed in 0.36s ======================================================================
mdanish@3be53d98ab67:/sonic/src/sonic-utilities$ pytest-3 tests/subintf_test.py 
==================================================================== test session starts =====================================================================
platform linux -- Python 3.9.2, pytest-6.0.2, py-1.10.0, pluggy-0.13.0
rootdir: /sonic/src/sonic-utilities/tests, configfile: pytest.ini
plugins: pyfakefs-5.0.0, cov-2.10.1
collected 7 items                                                                                                                                            

tests/subintf_test.py .......                                                                                                                          [100%]

===================================================================== 7 passed in 0.50s ======================================================================
mdanish@3be53d98ab67:/sonic/src/sonic-utilities$ 

Previous command output (if the output of a command-line utility has changed)

Example output with interface name Ethernet0 and vrf name Vrf1:

admin@sonic:~$ sudo config interface vrf bind Ethernet0 Vrf1
admin@sonic:~$ sudo config interface vrf unbind Ethernet0
admin@sonic:~$ sudo config vrf del Vrf1

New command output (if the output of a command-line utility has changed)

Example output with interface name Ethernet0 and vrf name Vrf1:

admin@sonic:~$ sudo config interface vrf bind Ethernet0 Vrf1
Interface Ethernet0 IPv4 disabled and address(es) removed due to binding VRF Vrf1
admin@sonic:~$ sudo config interface vrf unbind Ethernet0
Interface Ethernet0 IPv4 disabled and address(es) removed due to unbinding VRF
admin@sonic:~$ sudo config vrf del Vrf1
VRF Vrf1 deleted and all associated IPv4 addresses removed.

[linux-foundation-easycla]

The committers listed above are authorized under a signed CLA.

• ✅ login: hamnarauf / name: Hamna Rauf (3ea09a0)

[hamnarauf]

@prsunny @qiluo-msft @dgsudharsan @preetham-singh Please review.

[prsunny]

@prsunny @qiluo-msft @dgsudharsan @preetham-singh Please review.

looks ok to me but would like to know the motivation of the PR with such warnings? Giving such a message may fail the return value check for services invoking this function. I'll wait for @dgsudharsan and @preetham-singh to sign-off before merge?

[hamnarauf]

looks ok to me but would like to know the motivation of the PR with such warnings? Giving such a message may fail the return value check for services invoking this function. I'll wait for @dgsudharsan and @preetham-singh to sign-off before merge?

The intention is to print a helpful message that informs the user in case IP gets removed by the system from an interface to avoid user pit falling into an inconsistent configuration state. In my opinion, the user needs to be informed promptly to avoid ambiguity. Such helpful messages are present in other SONiC CLI commands as well.

[hamnarauf]

@prsunny @preetham-singh Please review again