Implement DATABASE_ENGINE Configuration Parameter

[nick-bogle]

NetBox version

v3.4.4

Feature type

New functionality

Proposed functionality

I am proposing introduction of a DATABASE_ENGINE parameter, which would allow overwriting the default database engine of 'django.contrib.gis.db.backends.postgresql' to a custom database backend.

This would be an optional configuration parameter within the configuration.py file. In the event METRICS_ENABLED was also set, I propose we give the DATABASE_ENGINE option priority. If DATABASE_ENGINE is not set, and METRICS_ENABLED is set to True, then the database engine would be set to 'django_prometheus.db.backends.postgresql'

Use case

This would allow extending the netbox datamodel with different Postgres database extensions, for example to support PostGIS to allow geospatial data models.

Database changes

No database changes.

External dependencies

No external dependencies until a database engine was overwritten, in which case that engine may potentially have external dependencies.

[nick-bogle]

If approved, I am happy to take ownership and complete the PR for this feature. This would allow plugins like this to be used: https://github.com/wholesailnetworks/netbox-geo

[jeremystretch]

Just a minor note: We probably want to add an ENGINE parameter to the existing DATABASE config (as opposed to establishing a separate setting), e.g.:

DATABASE = {
    'ENGINE': 'my.custom.backend',
    'NAME': 'netbox',
    'USER': 'netbox', 
    ...
}

To confirm, this would default to django.db.backends.postgresql (or, if METRICS_ENABLED is true, django_prometheus.db.backends.postgresql), but be overridden by any user-specified value.

I don't believe there's anything precluding this from being implemented in v3.4, so I'll assign it you @nick-bogle. Thanks!

[jeremystretch]

@nick-bogle are you still planning to work on this?