netbox/docs/plugins/development/events.md

Events

Plugins can register their own custom event types for use with NetBox event rules. This is accomplished by calling the register() method on an instance of the Event class. This can be done anywhere within the plugin. An example is provided below.

from django.utils.translation import gettext_lazy as _
from netbox.events import Event, EVENT_TYPE_SUCCESS

Event(
    name='ticket_opened',
    text=_('Ticket opened'),
    type=EVENT_TYPE_SUCCESS
).register()

::: netbox.events.Event