Docker DNS-gen

dns-gen sets up a container running Dnsmasq and docker-gen. docker-gen generates a configuration for Dnsmasq and reloads it when containers are started and stopped.

reference project docker-dns-gen，use template:

{{ define "host" }}
        {{ $host := .Host }}
        {{ $tld := .Tld }}
        {{ if eq $tld "" }}
            {{ range $index, $network := .Container.Networks }}
                {{ if ne $network.IP "" }}
    address=/{{ $host }}/{{ $network.IP }}
                {{ end }}
            {{ end }}
        {{ else }}
            {{ range $index, $network := .Container.Networks }}
                {{ if ne $network.IP "" }}
    address=/{{ $host }}.{{ $tld }}/{{ $network.IP }}
    address=/{{ $host }}.{{ $network.Name }}.{{ $tld }}/{{ $network.IP }}
                {{ end }}
            {{ end }}
        {{ end }}
    {{ end }}

    {{ $tld := or ($.Env.DOMAIN_TLD) "docker" }}
    {{ range $index, $container := $ }}
        {{ template "host" (dict "Container" $container "Host" $container.Hostname "Tld" $tld) }}
        {{ template "host" (dict "Container" $container "Host" $container.Name "Tld" $tld) }}
    {{ end }}

    {{ range $host, $containers := groupByMulti $ "Env.DOMAIN_NAME" "," }}
        {{ range $index, $container := $containers }}
            {{ template "host" (dict "Container" $container "Host" (print $host) "Tld" "") }}
        {{ end }}
    {{ end }}

And support tcp docker api endpoint .

build image

$ docker build -t jiadx/docker-dns-gen --rm .

Simple usage

start dns-gen ：

docker run -d --name dns-gen \
     --restart always \
     --publish 171.17.42.1:53:53/udp \
     --volume /var/run/docker.sock:/var/run/docker.sock \
     jiadx/docker-dns-gen

171.17.42.1 is docker0 bridge IP.

when you start container:

docker run -ti --rm -h hostname1 --name host1  centos:6.7 bash

the generated /etc/dnsmasq.conf looks like:

  address=/host1.docker/171.17.0.13
  address=/hostname1.docker/171.17.0.13

reference docker-dns-gen。

support user-defined network

create docker network:

docker network create --driver overlay --subnet=173.17.0.0/24 my-net

start container with user-defined network:

docker run -ti --rm -h hostname1 --name host1 --net my-net  centos:6.7 bash

the generated /etc/dnsmasq.conf looks like:

  address=/host1.docker/173.17.0.13
  address=/host1.my-net.docker/173.17.0.13
  address=/hostname1.docker/173.17.0.13
  address=/hostname1.my-net.docker/173.17.0.13