Invalid Handling of controller_managed_device_groups and Empty controller_group Causes Sync Errors in Nautobot SSOT

[TheHack42]

Environment

• Python version: 3.11.9
• Nautobot version: 2.3.2
• nautobot-ssot version: develop branch

Expected Behavior

The devices should be properly synchronized into Nautobot without exceptions. The controller_group should be set correctly, and the related ControllerManagedDeviceGroup should be retrieved based on the provided value or gracefully handled if empty.

Observed Behavior

There are two issues observed:

1. In the following code:
   https://github.com/nautobot/nautobot-app-ssot/blob/develop/nautobot_ssot/integrations/aci/diffsync/models/nautobot.py#L182

   controller_group=(
       self.job.apic.controller_managed_device_groups.name
       if self.job.apic.controller_managed_device_groups
       else ""
   )

   The variable self.job.apic.controller_managed_device_groups is a ManyRelation, not an instance of ControllerManagedDeviceGroup. As a result:

   • Accessing the name attribute on a ManyRelation return a None value.
   • The condition if self.job.apic.controller_managed_device_groups will always evaluate to true, which makes the current logic invalid.
   • Additionally, None is not allowed, and since the Pydantic validation requires a valid string, it throws an error: "Input should be a valid string".

2. In the following code:
   https://github.com/nautobot/nautobot-app-ssot/blob/develop/nautobot_ssot/integrations/aci/diffsync/adapters/aci.py#L438

   def create(cls, adapter, ids, attrs):
       """Create Device object in Nautobot."""
       _device = OrmDevice(
           name=ids["name"],
           role=Role.objects.get(name=attrs["device_role"]),
           device_type=OrmDeviceType.objects.get(model=attrs["device_type"]),
           serial=attrs["serial"],
           comments=attrs["comments"],
           controller_managed_device_group=ControllerManagedDeviceGroup.objects.get(name=attrs["controller_group"]),
           location=Location.objects.get(name=ids["site"], location_type=LocationType.objects.get(name="Site")),
           status=Status.objects.get(name="Active"),
       )

   The value of attrs["controller_group"] can be an empty string, and if so, the query for ControllerManagedDeviceGroup.objects.get(name=attrs["controller_group"]) will fail and raise a DoesNotExist exception.

Steps to Reproduce

1. Run the Nautobot SSOT synchronization job.
2. Ensure the synchronization involves a device with an empty or missing controller_group field.
3. The Pydantic validation error or DoesNotExist exception will occur.

Potential Fix

For the first issue:

• The controller_managed_device_groups being a ManyRelation should be handled accordingly, either by iterating through the related objects or adjusting the logic to handle the collection properly.

For the second issue:

• A check should be added to ensure attrs["controller_group"] is not empty or None before attempting to retrieve the ControllerManagedDeviceGroup. If it’s empty, either set a default value or skip the retrieval.

Thanks

[jdrew82]

@TheHack42 Thank you for opening this Issue. I've reviewed your comment and I think you might have some things flipped around. Specifically, it appears that the code examples you provide are flipped for the lines you cite. With that addressed, I wanted to respond to a few things:

• Prior to either adapters or CRUD operations happening there is a helper function that is called in the Job to ensure that there is a ControllerManagedDeviceGroup (CMDG) that exists and is attached to the specified APIC here. Due to this occurring there is an assumption that the specified APIC should have a defined CMDG attached to it.

• For point 1 you mention that controller_managed_device_groups is a ManyRelation. I wanted to correct you on that as you can see it's an FK from the ControllerManagedDeviceGroup class here. Because of the above point about expecting a CMDG exist on the APIC we should always get a resolved name for that object when loading the Device object. Also, it's explicitly written to return an empty string if for some reason there isn't a CMDG on the APIC.

• For point 2, again the expectation is that there should be a CMDG name defined when the adapter loads the Device. If for some reason there isn't one then it sounds like the helper function isn't working as expected?

[jdrew82]

@TheHack42 I think I see the ManyRelation now. That's a bit odd as the code does show it should be an FK. I'll work on getting a fix in for that.