When External - Coredns Io

+++ 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.