CoreDNS Etcd Backend

This is another etcd backend for coredns. I built this plugin for coredns because the current etcd plugin does not support multiple subdomains (coredns/coredns#2941). This plugin is based off the current Etcd plugin and the external redis plugin.

Using this plugin

To use this plugin you need to recompile CoreDNS with this plugin enabled. This is really easy with the use of go modules.

Clone the CoreDNS repo:

git clone https://github.com/coredns/coredns
cd coredns

Modify the plugin.cfg and add this plugin to it. Something like this:

...
etcd:etcd
coredns_etcd_backend:github.com/zbblanton/coredns_etcd_backend
redis:github.com/arvancloud/redis
sign:sign
...

Now just run:

make

Configuring the plugin works the exact same way the etcd plugin does. Look in the Syntax section of https://coredns.io/plugins/etcd/

Example:

awesomedomain.com:4000 {
    log
    errors
    coredns_etcd_backend {
        endpoint  http://127.0.0.1:2379
    }
}

Example with TLS:

awesomedomain.com:4000 {
    log
    errors
    etcd {
        endpoint  https://10.0.0.10:2379
        tls /data/coredns-etcd.crt /data/coredns-etcd.key /data/ca.crt
    }
}

Records

Create records by the reverse name. For example if you want to create an A record for test1.test.local you would do a put to etcd for /coredns/local/test/test1/-A-/record1. There are some exceptions to the last path name. For example for CNAME records it will end like /coredns/local/test/test1/-CNAME-.

NOTE: the name for record doesn't matter. The record1 above could be any name.

A

{
  "host": "10.0.0.102"
}

Example:

/coredns/local/test/test1/-A-/record1
{"host":"10.0.0.102"}
/coredns/local/test/test1/-A-/record2
{"host":"10.0.0.103"}

CNAME

{
  "cname": "testme.local"
}

Example:

/coredns/local/test/test1/-CNAME-
{"cname":"testme.local"}

TXT

{
  "text": "im a test 2"
}

Example:

/coredns/local/test/test1/-TXT-/record1
{"text":"im a test"}
/coredns/local/test/test1/-TXT-/record2
{"text":"im a test 2"}

SRV

{
  "target": "test.local",
  "weight": 10,
  "port": 2222,
  "priority": 0
}

Example:

/coredns/local/test/test1/test2/_tcp/_etcd-server-ssl/-SRV-/record1
{"target":"test.local","weight":10,"port":2222,"priority":0}
/coredns/local/test/test1/test2/_tcp/_etcd-server-ssl/-SRV-/record2
{"target":"test2.local","weight":10,"port":2222,"priority":10}

Notes

• Still working on wildcard support
• SOA will return a static record
• No reverse lookup at this time