Drank

This is alpha softare, has not been battle tested in production

Drank is a service discovery daemon for Docker. Drank advertises container hosts, containers and their service state to ZooKeeper for consumption. Drank is a "soft state" service. Stopping drank will cause the data it advertises to ZK to drop out. On start up drank will consume docker data again and repopulate ZK. Drank creates a session and ephemeral node for the container host where drank is running as well as a session and ephemeral node for each container.

Usage

    $ drank # uses defaults

    # start a service using docker and drank should detect it, using the SERVICE environment variable
    $ sudo docker run -d -e SERVICE=testservice -i -t ubuntu /bin/bash

Schema

/docker/services
/docker/services/SERVICENAME/CONTAINERHOST/CONTAINERID

/docker/container-hosts
/docker/container-hosts/CONTAINERHOST

Consuming Drank data from Zookeeper

vagrant@precise64:~$ irb
irb(main):001:0> require 'zookeeper'
=> true

irb(main):002:0> zk = Zookeeper.new("localhost:2181")
=> #<Zookeeper::Client:0x00000000d731b0>

irb(main):003:0> zk.get_children(:path => "/docker/services")[:children]
=> ["testservice"]

irb(main):004:0> zk.get_children(:path => "/docker/container-hosts")[:children]
=> ["precise64"]

irb(main):005:0> zk.get_children(:path => "/docker/services/testservice/precise64")[:children]
=> ["de659d7ceaa1a212fac17ad419289a451ab683d76ae68f0cf37adefa1a8bbb69", "38d63f37a4d9ab3269ac5993264575ce7e7219831f7360bcca3b41ccea507ab1"]

Hacking

You'll need to run inside a Vagrant VM if you are on Mac OS X. After checking out it out in your development environment, make accessible from inside a guest with a bit like thi sin Vagrantfile:

Vagrant::VERSION >= "1.1.0" and Vagrant.configure("2") do |config|
  config.vm.synced_folder "/path/to/drank", "/drank"
end

You'll need to vagrant reload to make it accessible. Then vagrant ssh to get inside.

$ cd /drank
$ script/setup
$ bin/drank

License

Drank is open source software available under the MIT License