This Docker images provides a simple proxy for tunneling requests to mDNS-enabled Docker containers via a single endpoint. This allows bridging regular DNS to mDNS name resolution transparently. The usage of this software may be useful in various situations, eg. using it together with Dnsmasq on macOS (with Docker for Mac) or as an regular entrypoint to a virtual machine or on a remote cloud instance.

A simple example setup requires a virtual machine, some mDNS-enabled containers running inside of it, this software running also inside of the virtual machine and some host entry configurations.

• Requirements
• Getting starting
• docker-compose usage example
• Rebind another external DNS suffix

Requirements

• A dedicated host where some mDNS-enabled containers are running (which will be made available on a single port of the host)

Getting starting

You just need to run it like that, to get a working ruby:

$ docker run -p 80:80 --rm hausgold/mdns-proxy

The binded host port is then linked to the mDNS proxy which will handle requests with various host headers (eg. test.local).

docker-compose usage example

services:
  ruby:
    image: hausgold/mdns-proxy
    environment:
      # The default, see "Rebind another external DNS suffix"
      MDNS_SUFFIX: .local
      # These root path entries will be upgraded to WebSocket
      # connections transparently. The following list is the default.
      WEBSOCKET_PATHS: 'cable|sockjs-node|livereload|ws'
      # Change the maximum upload size per request
      MAX_UPLOAD_SIZE: 20m

Rebind another external DNS suffix

You can modify the incomming host names by reconfiguring the MDNS_SUFFIX which defaults to .local. This way you can transparently rebind the host to a different DNS name. Say you have an AWS EC2 instance with some mDNS-enabled containers running and bind an IP to it. Setup an A DNS record for it like example.com and a wildcard to the very same host. Then you set MDNS_SUFFIX='.example.com' here and your can access your mDNS containers like this: app.example.com.