Provide a mechanism for plugins to attach arbitrary context to outgoing webhooks

[jeremystretch]

NetBox version

v4.3.5

Feature type

New functionality

Proposed functionality

Implement a mechanism by which plugins can contribute additional data to outbound webhooks generated in response to an event rule. This mechanism would enable a plugin to register a callback function to be called whenever a webhook is being generated. The callback would accept the object and current request, and return any data to be included in the webhook's payload.

Something like this:

@webhook_data(models=(Site, Location))
def my_plugins_callback(instance, request):
    if instance.tenant is not None:
        return {
            'billing_id': Customer.objects.get(tenant=instance.tenant)
        }

Any data returned by the callback will be attached to the webhook payload, e.g. within a context key on the JSON object root. (An empty response will be ignored.)

This should be implemented in a way so as not to break the current format of a webhook payload.

Use case

One example where this would be useful is in the netbox-branching plugin, where it would be helpful to attach the branch in which a change is being made as context. (See netboxlabs/netbox-branching#132 for some discussion around this use case.) However, it's not difficult to image other scenarios where this would be convenient.

Database changes

N/A

External dependencies

N/A

[jnovinger]

My only concerns here are about making sure we don't allow this to disrupt normal core behavior:

• Should we set a timeout, in case the plugin does something really ugly, like call really slow, outside APIs? At a minimum, we should definitely wrap this in a try-except.
• How do we/can we even ensure there's not data leakage? Or is that something we shouldn't ensure, given it would be part of the plugin API?
• How do we make sure this doesn't break existing webhook payloads? Use some sort of namespacing to insert it?