docker-dns-proxy

app1.example.00:80 -> (dnsmasq, nginx) -> app1.example container in "00" custom docker 1.9 network

--- docker machine --------------------------
------ net: 00 ------------------------------
 [app1.example], [app2.example] ...
   ^
   | http://app1.example.00/ (e.g. 172.19.0.2)
   |
   |              /etc/hosts    --address=/.00/192.168.99.100
 [nginx] ------> [dnsmasq_in]  [dnsmaq_out]
- :80 ----------- :5353 ---------- :53 ------ expose port
   ^                                ^
   | http://app1.example.00/ (192.168.99.100)
   |                                |
---- localhost ------------------------------
 [browser] <---------> [/etc/resolver/docker]

Prerequisites

docker 1.9

(I tested on OS X 10.10.5 with docker 1.9 installed by Kitematic.)

Assumptions

A docker-machine running on 192.168.99.100
You use docker custom network named 00
Use .00 as the TLD

Of course, you can alter those default if you wish.

Usage by example

Let localhost resolve `.00` TLD for the docker machine

sudo bash -c 'echo "nameserver 192.168.99.100" > /etc/resolver/00'

Create a custom docker network, `00`

$ docker network create 00

Run an app container for test

Run python SimpleHTTPServer for example as app1.example.

$ docker run -it --rm --net 00 --name app1.example python:2 python -m SimpleHTTPServer 80
Serving HTTP on 0.0.0.0 port 80 ...

Build and run docker-dns-proxy

$ docker-compose build

$ docker-compose --x-networking up
Starting dockerdnsproxy_dnsmasq_out_1
Starting dockerdnsproxy_dnsmasq_in_1
Recreating dockerdnsproxy_nginx_1
Attaching to dockerdnsproxy_dnsmasq_out_1, dockerdnsproxy_dnsmasq_in_1, dockerdnsproxy_nginx_1
...

Test!!

Enter http://app1.example.00 in your browser or curl http://app1.example.00.

Reload dnsmasq

If you restart the app container or run another app container, you may get 502 Bad Gateway. dnsmasq won't reload /etc/hosts automatically. You need let the dnsmasq process to reload /etc/hosts.

docker kill -s HUP dockerdnsproxy_dnsmasq_in_1

docker-compose restart dnsmasq

or simply shutdown and up docker-compose.

(I want a simple "watch /etc/hosts and HUP dnsmasq container if I can...)

MaxLevs/docker-dns-proxy