dockness

DNS for Docker machines, allows to access them with the following domain format : {machine}.docker.

• How it works
• Installation
• Usage
• Configure as a service

How it works

It spins up a simplistic DNS server, only listening for questions about A records.

Behind the scene it will use libmachine in order to resolve IP addresses.

Installation

Prebuilt binaries

Prebuilt binaries are available in the releases.

From source (requires Go)

go get github.com/bamarni/dockness

With Homebrew (Mac OS X)

brew tap mkw/homebrew-mkw
brew install dockness

Usage

dockness [options...]

Options:
  -tld    Top-level domain to use (defaults to "docker")
  -ttl    Time to Live for DNS records (defaults to 0)
  -port   Port to listen on (defaults to "53")
  -debug  Enable debugging (defaults to false)

Mac OSX

To develop on Mac you probably have a local VM, using VirtualBox for example. However this machine gets assigned a dynamic IP address.

You can be up and running in a few commands, first :

> echo -e "nameserver 127.0.0.1\nport 10053" | sudo tee /etc/resolver/docker

It tells your Mac that the resolver for .docker TLD listens locally on port 10053. You can now run the resolver on this port :

> dockness -port 10053
2016/02/18 10:39:52 Listening on :10053...

Linux

Even though Linux users might not need a development VM, it can be useful for remote machines (eg. ssh staging2.docker, ...).

Here and unlike Mac OSX, there is no quick trick to make it work out of the box. Linux distributions come with more advanced DNS management where manually tweaking resolv.conf is usually not an option.

What should work in most cases is to use Dnsmasq, which provides a lightweight DNS server.

If you have it installed, you can run :

> dockness -port 10053
2016/02/18 10:40:43 Listening on :10053...

Then let Dnsmasq know about the resolver by running those commands :

> echo "server=/docker/127.0.0.1#10053" | sudo tee -a /etc/dnsmasq.conf
> sudo /etc/init.d/dnsmasq restart

Configure dockness as a service

As it's not very convenient to run the program manually in a terminal, you can instead set it as a service. Doing so, it will be running in the background automatically when booting your computer.

Mac OSX

You can create the appropriate service configuration file at ~/Library/LaunchAgents/local.dockness.plist :

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
        <key>Disabled</key>
        <false/>
        <key>Label</key>
        <string>local.dockness</string>
        <key>ProgramArguments</key>
        <array>
                <string>/path/to/dockness</string>
                <string>-port</string>
                <string>10053</string>
        </array>
        <key>RunAtLoad</key>
        <true/>
</dict>
</plist>

Finally, the service can be enabled :

launchctl load ~/Library/LaunchAgents/local.dockness.plist

Linux

Here again, it will depend on your Linux distribution. We'll take as example Systemd, which is nowadays the default init system in most distributions.

Create the following file at /etc/systemd/system/dockness.service:

[Unit]
Description=Dockness
After=network.target

[Service]
ExecStart=/path/to/dockness -port 10053

[Install]
WantedBy=multi-user.target