Exception raised when cable trace ends at a rear port with no peer front port

[ThomasADavis]

Environment

• Python version:

python3.6

• NetBox version:

v2.10-beta1

Steps to Reproduce

1. install v2.10
2. use existing v2.9.9 db.
3. errors out.

Expected Behavior

install completed.

Observed Behavior

Retracing 1652 cabled interfaces...
  1000
Traceback (most recent call last):
  File "netbox/manage.py", line 10, in <module>
    execute_from_command_line(sys.argv)
  File "/opt/netbox-2.10-beta1/venv/lib64/python3.6/site-packages/django/core/management/__init__.py", line 401, in execute_from_command_line
    utility.execute()
  File "/opt/netbox-2.10-beta1/venv/lib64/python3.6/site-packages/django/core/management/__init__.py", line 395, in execute
    self.fetch_command(subcommand).run_from_argv(self.argv)
  File "/opt/netbox-2.10-beta1/venv/lib64/python3.6/site-packages/django/core/management/base.py", line 330, in run_from_argv
    self.execute(*args, **cmd_options)
  File "/opt/netbox-2.10-beta1/venv/lib64/python3.6/site-packages/django/core/management/base.py", line 371, in execute
    output = self.handle(*args, **options)
  File "/opt/netbox-2.10-beta1/netbox/dcim/management/commands/trace_paths.py", line 75, in handle
    create_cablepath(obj)
  File "/opt/netbox-2.10-beta1/netbox/dcim/signals.py", line 16, in create_cablepath
    cp = CablePath.from_origin(node)
  File "/opt/netbox-2.10-beta1/netbox/dcim/models/cables.py", line 422, in from_origin
    node = FrontPort.objects.get(rear_port=peer_termination, rear_port_position=position)
  File "/opt/netbox-2.10-beta1/venv/lib64/python3.6/site-packages/django/db/models/manager.py", line 85, in manager_method
    return getattr(self.get_queryset(), name)(*args, **kwargs)
  File "/opt/netbox-2.10-beta1/venv/lib64/python3.6/site-packages/cacheops/query.py", line 353, in get
    return qs._no_monkey.get(qs, *args, **kwargs)
  File "/opt/netbox-2.10-beta1/venv/lib64/python3.6/site-packages/django/db/models/query.py", line 431, in get
    self.model._meta.object_name
dcim.models.device_components.DoesNotExist: FrontPort matching query does not exist.
[root@netbox-dev netbox]# 

[jeremystretch]

Can you determine the FrontPort instance causing the error? If you run ./manage.py nbshell and enter the following, it should give you the ID of the originating interface from the failed trace:

Interface.objects.filter(cable__isnull=False).first().pk

Then, you can navigate to http://netbox/dcim/interfaces/<id>/ to see what the interface is cabled to.

[ThomasADavis]

I blew away that dev db, and re-created it from a 2.8.9 system, and it still occurs. I have not done anything more to this db.

Here's the results:

(venv) [root@netbox-dev netbox]# ./netbox/manage.py nbshell
### NetBox interactive shell (netbox-dev)
### Python 3.6.8 | Django 3.1.3 | NetBox 2.10-beta1
### lsmodels() will show available models. Use help(<model>) for more info.
>>> Interface.objects.filter(cable__isnull=False).first().pk
4585

Screen shots of both ends of 4585

[jeremystretch]

My apologies, I gave you an incorrect query to run. Please try the following:

Interface.objects.filter(cable__isnull=False, _path__isnull=True).first().pk

This should reveal the originating interface which results in the failed trace.

[ThomasADavis]

ah. it's a hydra cable into a patch panel, then a trunk to another patch panel.. and it ends there. there is only 1 device attached, and the other end is waiting to be used.

[jeremystretch]

Thanks! I've been able to reproduce the bug locally. It seems to be caused by the absence of a front port associated with the ending rear port, but it should be easy enough to work around.

[jeremystretch]

Should have it fixed now. You can clone the develop-2.10 branch to test, or just wait for the v2.10-beta2 release later this week. Please let me know if you still encounter issues after that.