Refactor Provider to require DomainFilter

[johngmyers]

Description

Refactors the Provider interface to require a concrete DomainFilter instead of just any DomainFilterInterface. The purpose of this is to allow the upcoming Webhook provider to implement GetDomainFilter by having the negotiation phase return information needed to construct a copy of the target Provider's DomainFilter.

Checklist

• Unit tests updated
• End user documentation updated

[Raffo]

GetDomainFilter by having the negotiation phase return information needed to construct a copy of the target Provider's DomainFilter.

@johngmyers can you add more information on how this is supposed to work ?

[johngmyers]

We'd have to implement a method of serializing DomainFilter. That could be by having it implement Marshaler and Unmarshaler or by making fields public and putting json tags on them.

The serialized form would consist of the Filters and excludes arrays, plus regex.String() and regexExclusion.String().

The negotiation call (or other call made upon startup) would pass this serialized form from webhook to external-dns. The webhook Provider would deserialize this to a DomainFilter which it would then return from GetDomainFilter.

[Raffo]

/approve
/lgtm

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: johngmyers, mloiseleur, Raffo

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