Interface query via API returns too many interfaces since v2.11.2

[cs-1]

NetBox version

v2.11.2

Python version

3.8

Steps to Reproduce

1. Create at least two devices with the naming scheme "myname/1" and "myname/2" (number after "/" corresponds with the stack member ID in our case).
2. Create a virtual chassis called "myname" and add devices "myname/1" and "myname/2" as members. Do not make one of the members a master.
3. Query NetBox using the following GET request:

https://<netbox-server>/api/dcim/interfaces/?device=myname%2F1

Expected Behavior

In NetBox v2.11.1 the above query would produce only interface data of the VC member "myname/1".

Observed Behavior

After upgrading to v2.11.2 this produces the interfaces of all devices in the same virtual chassis despite none of the VC members being master. Please note that this query also produces all interfaces of all devices when querying "myname/2"'s interfaces.

We can clearly pin this on some change in v2.11.2. We used a VM snapshot of the v2.11.1 server to verify this and I can confirm that this behaviour was not present in v2.11.1.

Deleting the virtual chassis "myname" will immediately remedy this problem. So this is related to the fact that the devices are members of a virtual chassis.

This issue can be reproduced in Swagger.

[jeremystretch]

Please update your steps to reproduce to use raw API requests. We cannot rely on third party tools for bug reproduction.

[cs-1]

Sorry, @jeremystretch , I updated the steps to reproduce giving the raw API call. You can actually reproduce it in the Swagger interface, too.

[cs-1]

I've added further clarification. I'll try to find out today which change in v2.11.2 causes this bug.

[cs-1]

@jeremystretch I found what causes the problem. It seems to be caused by the addition of if_master:

netbox/netbox/dcim/models/devices.py

Line 877 in 1abaa5e

if self.virtual_chassis and (not if_master or self.virtual_chassis.master == self):

Removing not if_master or (the way it was before in v2.11.1) fixes the problem, a different way is to change the default to if_master=True. It looks like, due to if_master being False by default, the line

netbox/netbox/dcim/models/devices.py

Line 877 in 1abaa5e

if self.virtual_chassis and (not if_master or self.virtual_chassis.master == self):

will always evaluate to True. As far as I can tell if_master is only set to True in https://github.com/netbox-community/netbox/blob/1abaa5e60c2ecc15ae57db978d389023c136bdf7/netbox/dcim/views.py and in all other cases the interfaces of all chassis members will always be filtered and shown. This seems to be true for API GET calls to get interfaces of a VC member as well (though this wasn't the case in v2.11.1). It looks like whatever calls this function when using the interfaces API GET request needs to add if_master=True to the function call.

Thanks for looking into this!

[cs-1]

Hi @jeremystretch ,

I've spent the weekend thinking about the reasoning behind adding the if_master attribute. If it's ok with you I'd like to ask you some questions about it to understand where to look for a fix for the issue it introduced.

As far as I understand the reason for adding if_master is so that it's possible to query all interfaces of members of the same virtual chassis by using a single call of vc_interfaces() so that LAGs can be configured by using any interface of all virtual chassis members even if none of them is designated as a master chassis. To achieve this, you introduced the if_master variable. To avoid having to change all code calling vc_interfaces() you set it to a default of False so that calling vc_interfaces() without any parameters would behave as it did before which is to only show the interfaces of a particular virtual chassis member and not all interfaces of all chassis members unless the chassis being queried is a master chassis. Is this assumption correct? If it is, the expression in

netbox/netbox/dcim/models/devices.py

Line 877 in 1abaa5e

if self.virtual_chassis and (not if_master or self.virtual_chassis.master == self):

needs to be changed to

if self.virtual_chassis and (if_master or self.virtual_chassis.master == self):

That way the code will behave as in v2.11.1 if vc_interfaces() is called without parameter: it will leave the filter untouched an hence only show the interfaces of the virtual chassis member that's being queried and it will only modify the filter to show all interfaces of all virtual chassis members if the chassis queried is the virtual chassis master. If vc_interfaces(if_master=True) is called (as is the case in netbox/dcim/views.py) it will show all interfaces of all virtual chassis members even if the chassis queried isn't a virtual chassis. If I'm wrong and the intention is that a call of vc_interfaces() without parameters will yield all interfaces of all virtual chassis members and it should only return just the interfaces of a virtual chassis member if it's called with parameter as vc_interfaces(if_master=True) then I assume that, when issuing the API GET call, vc_interfaces() is for some reason called without if_master=True.

Sorry for the lengthy post, my insight into the NetBox code isn't very deep hence the questions. I'd really like to help fixing this. The impact of this change is quite dramatic for us because it breaks all of our Ansible playbooks.