Support the use of NetBox features by plugin models

[jeremystretch]

NetBox version

v3.1.6

Feature type

New functionality

Proposed functionality

Officially support the use of various NetBox features by plugin models. These include:

• Custom fields
• Custom links
• Custom validation
• Export Templates
• Journaling
• Tags
• Webhooks

For each feature above, we should introduce (or repurpose) a class which a model can inherit to enable the feature. For example, a TagsMixin class would enable the assignment of tags, and a CustomLinksMixin would enable custom links.

In the interest of cleanliness, we probably also want to introduce a base model class (e.g. BaseModel) that inherits all such feature mixins. A plugin model can then simply inherit from BaseModel to enable all features (while reserving the option to inherit only specific mixin classes if only a subset of features is desired).

I'd like to do away with the extras_features() decorator that's currently used to register features for specific models, as it's redundant for features which require additional fields or attributes on the model (see #8373). We may be able to leverage Django's class_prepared signal to automate this process.

Use case

This initiative will enable plugin authors to make use of many valuable features built into NetBox in a convenient and supported way.

Database changes

No response

External dependencies

No response

[jeremystretch]

I've made good progress with this already. Ditched the extras_features() decorator entirely, and refactored the base model classes. Still have some work to do, but I'm very encouraged by the results so far.

As this is the first major extension of the plugins framework since its introduction, I'm also going to be working on rebuilding the documentation. I've enlisted mkdocstrings for code introspection, which will help immensely. A rough working example is below.

[jeremystretch]

Extended the list above to include custom validation, and remove job results as a default feature.