+++
date = "2017-07-23T22:00:00Z"
description = "When should plugins be external?"
tags = ["Plugin", "External", "Out-of-Tree"]
title = "When Should Plugins be External?"
author = "miek"
+++

The `plugin.md` in the CoreDNS source tree has some pointers on what a plugin for CoreDNS
should have as minimum requirements. It basically boils down to: "it should add something unique and
useful to CoreDNS". Further more documentation, tests and functionality should all be excellent.

It is easier to list when a plugin can be *included* in CoreDNS than to say it should stay
external, so we will do that:

* First, the plugin should be useful for *other* people. "Useful" is a subjective term, but the
  plugin needs to fill a niche that appeals to more than one person.
* It should be sufficiently different from other plugins 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.
* Care must be taken to make it efficient in both memory and CPU.

Plugins for CoreDNS can easily live out-of-tree, `plugin.cfg` defaults to CoreDNS' repo but other
repos work just as well.