database_url.rb

unless ENV['DATABASE_URL'].present?
  # convert current config/database.yml to ENV['DATABASE_URL'] format
  c = ActiveRecord::Base.configurations[Rails.env]

  database = c["database"]
  username = c["username"]
  password = c["password"]
  adapter  = c["adapter"]  || "postgres"
  hostname = c["host"]     || "localhost"
  
  ENV['DATABASE_URL'] = [
    adapter,
    "://",
    (username ? "#{username}:" : ""),
    (username && password ? password : ""),
    (username ? "@" : ""),
    hostname,
    "/",
    database
  ].join("")
end

@tobin Hoping to never actually need this, but worth sharing incase. =P