dotCloud postinstall to overwrite database.yml for rails app

postinstall

#!/usr/bin/env ruby
require 'yaml'

DB_ADAPTER = "postgresql"
DATABASE = "my_database"
ENCODING = 'utf8'
TEMPLATE = 'template0'
TIMEOUT = 5000
POOL = 5

def load_dotcloud_env
  env = YAML.load(IO.read('/home/dotcloud/environment.yml'))
end

def overwrite_database_file
  env = load_dotcloud_env
  database = {
    'production' => {
      'adapter' => DB_ADAPTER,
      'database' => DATABASE,
      'host' => env['DOTCLOUD_DB_SQL_HOST'],
      'port' => env['DOTCLOUD_DB_SQL_PORT'].to_i,
      'username' => env['DOTCLOUD_DB_SQL_LOGIN'],
      'password' => env['DOTCLOUD_DB_SQL_PASSWORD'],
      'encoding' => ENCODING,
      'template' => TEMPLATE,
      'timeout' => TIMEOUT,
      'pool' => POOL
    }
  }
  File.open('config/database.yml', 'w') do |file|
    file.write database.to_yaml
  end
end

puts '=== Start to overwrite database.yml ==='
overwrite_database_file
puts '=== Finished overwriting! ==='

This file is intended to use with PostgreSQL with default dotCloud database settings, but also can be modified to fit with MySQL as well.
Don't forget to make this file executable by chmod +x postinstall