Custom record types in NetBox DNS

[peteeckel]

It took a while to find a way to navigate between strict adherence to RFCs and frequent wishes for non-standard RR types. There are good arguments for both approaches, and generally my tendency is towards strictness, especially considering interoperability issues.

With PR #599 I added a new functionality that should solve the issue in a way that makes (almost) everyone happy.

There is a new configuration variable custom_record_types that can hold an array of record types that are permitted in NetBox DNS in addition to the RFC types. It holds an array of strings that will be accepted for the type field in Record and RecordTemplate objects.

Records can be created, managed and exported for these types, but there are some restrictions:

Testing

The functionality is not subject to automated testing. This has reasons internal to the code base, and I'm investigating how to get this fixed, but it doesn't have a very high priority.

Validation

There is no validation at all for custom record types. Since they are not standardised and not covered by dnspython there is no way to provide a reliable validation for the format and contents of these records. If validation is needed, NetBox custom validators can be used for it, but they have to be provided by the user. As always, example code is welcome and can be included in the examples section if desired.

ForTXT records, values will be validated in a stricter way. One thing that will be handled automatically for TXT is the length of the data, which is broken into 255 character sements if necessary. Even this will not be done for custom records! The integrity of the data of custom records is entirely in the responsibility of the user.

That said, I hope this feature will solve some pain points for specific use cases.

Thanks @insignia96, @alainstucki, @alehaa and everyone else who poked me until I gave up :-)