[WIP] Add dynapi plugin

[syndbg]

Intro:

The goal of this PR is to have the dynapi plugin moved from coredns/coredns#1822 to this repository.

The "dynamic registration" part will remain inside coredns/coredns since other "base" plugins need to implement it.

The dynamic CRUD API for DNS records will live here.

Why is this not in the coredns/coredns

* First, the plugin should be useful for other people. "Useful" is a subjective term. We will probably need to further refine this.
* It should be sufficiently different from other plugin to warrant inclusion.
* Current internet standards need be supported: IPv4 and IPv6, so A and AAAA records should be handled (if your plugin is in the business of dealing with address records that is).
* It must have tests.
* It must have a README.md for documentation.

First and foremost it must be observed how useful the plugin is to other people. Obviously there's some interest, but no clear stats are observed at the moment.

Lets get this started before jumping to the main repository (if ever).

Ref: https://github.com/coredns/coredns/blob/master/plugin.md#qualifying-for-main-repo

What needs to be done in github.com/coredns/dynapi

Action plan is based on common sense, https://github.com/coredns/coredns/blob/master/plugin.md and the quality of other CoreDNS plugins such as:

• https://github.com/coredns/alternate
• https://github.com/coredns/kubernetai
• https://github.com/coredns/unbound
• https://github.com/coredns/fallback

• Extract only the dynapirest part from [WIP] Dynamic updates API with listen server coredns#1822
• Add README.md that satisfies the criteria of:
  • Having a name that briefly explains the purpose
  • Having a description that goes into more detail regarding the purpose
  • Having an install section that explains how to use this plugin with CoreDNS.
  • Having a syntax section explaining the accepted arguments by the plugin
  • Having an examples section which shows basic Corefile(s) with usage of the plugin for different scenarios
  • Clear API documentation of what endpoints are provided and what request and response bodies are used
  • Bugs/edge-cases/notes explicitly mentioned and/or described
• Have unit tests
• Have logging via "github.com/coredns/coredns/plugin/pkg/log" that covers the INFO/DEBUG/ERR cases at least, to make debugging and traceability easier.

Signed-off-by: Anton Antonov anton.synd.antonov@gmail.com

[vtolstov]

any progress?

[syndbg]

@vtolstov Didn't start anything. Will do it this weekend.

[piaoyu]

@syndbg it's very useful for us . And I put coredns/coredns#1822 merge into coredns and write the etcd plugin. Waiting for the dynapi plugin

[unixfox]

Any news? I'm also interested into this plugin for updating records with the dynamic IP of my home server.

[vtolstov]

ping, do you plan to finish this?

[syndbg]

@vtolstov Yes. I have this week free for Open-source work.

The reason why I haven't exactly finished this is cause in the last few months of production usage led me to make few changes. Will share more.

[mrueg]

Would be awesome to see progress on this one! Is your plan to be compliant with https://tools.ietf.org/html/rfc2136 ?

[gregorybrzeski]

@syndbg can you provide some update information on this ? is there any code you can share so we can try to help ?