One Database Per Branch, Per Environment

boot.rb

CURRENT_BRANCH = `git status | head -1`.to_s.gsub('# On branch ','').chomp

database.yml

<% 
database_prefix = 'app'
environments = %W( development test ) 
%>

defaults: &defaults
  pool: 5
  adapter: mysql2
  encoding: utf8
  reconnect: false
  username: root
  password: 
  host: localhost
  
<% environments.each do |environment| %>
<%= environment %>:
  <<: *defaults
  database: <%= [ database_prefix, CURRENT_BRANCH, environment ].join('_').underscore %>
<% end %>

If you want to include this dynamic database file in a rake or capistrano task you may need to do something like this:

  CURRENT_BRANCH = `git status | head -1`.to_s.gsub('# On branch ','').chomp
  @environment_info = YAML::load( ERB.new( IO.read( File.join( 'config', 'database.yml' ) ) ).result )["development"]

Just added a .underscore call at the end of the interpolated database string. Wasn't happy when a git branch had a "-" in it.