CoreDNS

CoreDNS is DNS server that started as a fork of Caddy. It has the same model: it chains middleware.

It is in the early stages of development on should be used on production servers. For now most documentation is in the source and some blog articles can be found here.

https://caddyserver.com/ is also full of examples on how to structure a Corefile (renamed from Caddyfile when I forked it).

Resolver

Start a simple resolver (proxy):

Corefile contains:

.:1053 {
    proxy . 8.8.8.8:53
}

Just start CoreDNS: ./coredns. And then just query on that port (1053), the query should be forwarded to 8.8.8.8 and the response will be returned.