[config] Add vlan member only after checking RIF is not present

[ghost]

What I did

Resolves sonic-net/sonic-buildimage#7028
Updated mechanism how to check is the port has RIF or not before adding it the port to the Vlan.
The related unit tests updated.

Copied implementation of port_util from swsssdk to utilities_common of sonic_utilities. Replaced using of swsssdk to utilities_common.

How I did it

By using functionality of port_util.py to check whether a RIF is present for the port in the system.
Now, the user can add a member to the Vlan only if there are no router records(ASIC_STATE:SAI_OBJECT_TYPE_ROUTER_INTERFACE:) in ASIC_DB, linked to OID of the interface.

How to verify it

1. sudo config interface ip add Ethernet0 30.0.0.1/24
2. sudo config route add prefix 20.0.0.1/32 nexthop Ethernet0
3. sudo config interface ip remove Ethernet0 30.0.0.1/24
4. sudo config vlan add 30
5. sudo config vlan member add --untagged 30 Ethernet0
   The last command will return the next error: Error: Ethernet0 is a router interface! Check assigned L3 addresses, a related static routes etc.
6. sudo config route del prefix 20.0.0.1/32 nexthop Ethernet0
   This will delete the route and RIF for the port.
7. sudo config vlan member add --untagged 30 Ethernet0
   The port will be added successfully,

Previous command output

admin@sonic:~$ sudo config vlan member add 30 Ethernet0
Usage: config vlan member add [OPTIONS] <vid> port
Try "config vlan member add -h" for help.

Error: Ethernet0 is a router interface!

New command output

Output of command config vlan member add for the case is little bit clarified to help user to understand that is going on.

admin@sonic:~$ sudo config vlan member add 30 Ethernet0
Usage: config vlan member add [OPTIONS] <vid> port
Try "config vlan member add -h" for help.

Error: Ethernet0 is a router interface! Check assigned L3 addresses, a related static routes etc.

[lguohan]

no more swsssdk, it is deprecating.

[ghost]

Got it. I am sorry, but I cannot find an alternate for port_util in swsscommon or any other places. Are there plans to implement something similar to port_util to swsscommon or somewhere else? I see the some scripts are still using port_util. I think the alternative will be useful.
If not, I am going to implement all the necessary directly inside vlan.py.

[ghost]

As I said before, port_util is still can be useful, so, I decided to copy its implementation to utilities_common of sonic_utilities.
I have found all places in sonic_utilities, where port_util is imported from swsssdk and replaced them to import from utilities_common.

[anshuv-mfst]

@prsunny - FYI

[ghost]

retest this please

[ghost]

@lguohan, @prsunny, could I ask you to review the PR?

[prsunny]

IMO, the existing check is sufficient. I think the reported issue must be handled differently. I've provided my comments in the issue - sonic-net/sonic-buildimage#7028

[ghost]

@prsunny, I think my changes will be a more robust solution to check whether the port is RIF of not, because it checks the result of deleting of the RIF(absence of the related record in ASIC_DB), rather then checking of records in CONFIG_DB, which represent desirable state of RIFs, but, not guarantee that the RIF is completely deleted, like in case with static route.
Maybe, it is not a full fix for the issue, but, I think, it is a good enhancement for the RIF checking mechanism.
Regarding your proposal to check whether a static route present or not before deleting ip entry. I thought about such solution. It may be more complicated, then only checking presence of the RIF, because, in my understanding, we should read the all routes and check whether the related routes presents or not. Also. we should check are there any other IP entries, assigned to the port or not, because the RIF will be deleted only after deleting of all the IP entries and before that, a static routes could be valid. Because of that, I decided to stay on checking of RIF on the port.
If checking of static routes on deleting of IP entry is desirable check, I could try to implement something such thing and add to this PR.

[prsunny]

Adding static route is not a typical use-case, as we already know that static route is not persisted across reboots. Also the fix cannot be considered complete, as adding such a port to portchannel should also be then returning failure. IMO, it is adding more overhead than simple checking for IP address in config_db.