Implement external-dns' webhook provider interface

[mrueg]

Is your feature request related to a problem? Please describe.
External-DNS is trying to reduce the number of internal DNS providers. It implemented support for webhooks to communicate with external providers for specific DNS (see: https://kubernetes-sigs.github.io/external-dns/v0.17.0/docs/tutorials/webhook-provider/ https://github.com/kubernetes-sigs/external-dns/blob/master/provider/webhook/webhook.go)

Describe the solution you'd like
It would be nice if dnscontrol could implement the webhook provider interface. This would likely increase the userbase of dnscontrol as well as reduce maintenance efforts on both sides for the same providers.

Describe alternatives you've considered
Write an external webhook service like https://github.com/mrueg/external-dns-netcup-webhook/ that interacts with dnscontrol' binary or embeds dnscontrol.

Additional context
Add any other context or screenshots about the feature request here.

[tlimoncelli]

It's good to see external-dns is becoming more generic!

However dnscontrol is a command-line tool, not a service that runs 24/7. How do you imagine this would work?

[mrueg]

I can see two options:

• dnscontrol could run a http server, which then will be utilized by external-dns directly (so it would read provider config from file input and the DNS config through the http endpoints (this will require changes to dnscontrol)

• An external webhook provider receives the input from external-dns and creates a file that dnscontrol is able to read. This tool would invoke the dnscontrol binary to then execute the changes (this doesn't require changes to dnscontrol but is more complex)

[tlimoncelli]

Yeah, I agree that those are the options.

Currently my time for DNSControl is limited to features that my employer needs. While we use k8s, we don't need this kind of integration.

I'd be glad to consult with anyone interested in doing a project like this.