Make docker machine available under host name in Windows

Question

I'm trying to make a docker machine available to my Windows by a host name. After creating it like

docker-machine create -d virtualbox mymachine

and setting up a docker container that exposes the port 80, how can I give that docker machine a host name such that I can enter "http://mymachine/" into my browser to load the website? When I change "mymachine" to the actual IP address then it works.

There is an answer to this question but I would like to achieve it without an entry in the hosts file. Is that possible?

Answer 1

If you're on a machine with Multicasting DNS (that's Bonjour on a Mac), then the approach that's worked for me is to fire up an Avahi container in the Docker Machine vbox. This lets me refer to VM services at <docker-machine-vm-name>.local. No editing /etc/hosts, no crazy networking settings.

I use different Virtualbox VMs for different projects for my work, which keeps a nice separation of concerns (prevents port collisions, lets me blow away all the containers and images without affecting my other projects, etc.)

Using docker-compose, I just put an Avahi instance at the top of each project:

version: '2'
services:
    avahi:
        image: 'enernoclabs/avahi:latest'
        network_mode: 'host'

Then if I run a webserver in the VM with a docker container forwarding to port 80, it's just http://machine-name.local in the browser.

Answer 2

Connecting by hostname requires that you go through hostname to IP resolution. That's handled by the hosts file and falls back to DNS. This all happens before you ever touch the docker container, and docker machine itself does not have any external hooks to go out and configure your hosts file or DNS servers.

With newer versions of Docker on windows, you run containers with HyperV and networking automatically maps ports to localhost so you can connect to http://localhost. This won't work with docker-machine since it's spinning up virtualbox VM's without the localhost mapping.

If you don't want to configure your hosts file, DNS, and can't use a newer version of docker, you're left with connecting by IP. What you can do is use a free wildcard DNS service like http://xip.io/ that maps any name you want, along with your IP address, back to that same IP address. This lets you use things like a hostname based reverse proxy to connect to multiple containers inside of docker behind the same port.

One last option is to run your docker host VM with a static IP. Docker-machine doesn't support this directly yet, so you can either rely on luck to keep the same IP from a given range, or use another tool like Vagrant to spin up the docker host VM with a static IP on the laptop. Once you have a static IP, you can modify the host file once, create a DNS entry for every dev, or use the same xip.io URL, to access the containers each time.