docker-devdns

A Dockerized version of @robbiev's https://github.com/robbiev/devdns.

Usage

This image is based off of the google/golang image.

Run it on port 5300 and have it return 127.0.0.1 for every DNS request it gets:

$ docker run -p 5300:5300/udp robmadole/devdns:latest
2015/01/09 17:19:38 Listening on 0.0.0.0:5300, resolving to 127.0.0.1

Since DNS works on UDP make sure that you use /udp when making the port mapping.

Now we can query the DNS server with any domain and always get back a deterministic value.

$ dig -p 5300 mysite.dev @localhost

Or if you're using Boot2Docker:

$ dig -p 5300 mysite.dev @`boot2docker ip`

What next?

If you are using OS X you can create a file inside of /etc/resolver called dev and tell it to use your devdns container.

Tip use boot2docker ip to figure out what IP address you need to assign nameserver to if you are using Boot2Docker.

/etc/resolver/dev:

nameserver 192.168.59.103
port 5300

To change the IP address that it answers with use the ANSWER environment variable.

$ docker run -e ANSWER=10.9.8.7 -p 5300:5300/udp robmadole/devdns:latest
2015/01/09 18:13:08 Listening on 0.0.0.0:5300, resolving to 10.9.8.7