Unable to pin a virtual machine to device in cluster due to difference in site

[rodvand]

NetBox version

v3.3.4

Python version

3.8

Steps to Reproduce

1. Create sites DC1 and DC2
2. Create a cluster named Stretched (type doesn't matter). Do not assign it to a Site.
3. Create two devices, device_dc1, device_dc2 and assign them to site DC1 and DC2
4. Add device_dc1, device_dc2 to your cluster Stretched.
5. Create a virtual machine vm_dc1
6. Assign it to the cluster Stretched, and try to pin it to device_dc1

Expected Behavior

To be allowed to pin the virtual machine to a specific device in the cluster.

Observed Behavior

You get an error message saying "The selected device (device_in_ds1 is not assigned to this site (None).". To get it to work I have to assign the cluster to the site DC1, but I can't do that either because the cluster contains devices not in DC1. If all devices in the cluster is the same Site, and the Cluster is assigned a Site the functionality works as expected.

I thought about raising this as an FR, but I think the fact that I can create a cluster and have devices in multiple sites assigned to the cluster I should also be able to pin a virtual machine to these devices.

I believe the logic for this is in the below code, but I'm not quite sure what should change.

netbox/netbox/virtualization/models.py

Lines 349 to 359 in 53f5f46

	# Validate site for cluster & device
	if self.cluster and self.site and self.cluster.site != self.site:
	raise ValidationError({
	'cluster': f'The selected cluster ({self.cluster} is not assigned to this site ({self.site}).'
	})
	elif self.cluster:
	self.site = self.cluster.site
	if self.device and self.device.site != self.site:
	raise ValidationError({
	'device': f'The selected device ({self.device} is not assigned to this site ({self.site}).'
	})

[jeremystretch]

I think it makes sense to just relax the device validation logic if the cluster is not assigned to a site.