Rails: retry connecting to Postgres

database.yml

development: &default
  adapter: postgresql
  database: app_development
  connect_retry_timeout: 1

pg.rb

# Make Postgres gracefully retry to create a connection. This lets us
# restart Postgres during our deploys without causing page loads to fail.

module PGConnectRetryTimeout
  def initialize(*args)
    error   = nil
    timeout = args.first.delete :connect_retry_timeout
    Timeout.timeout timeout do
      begin
        super
      rescue => error
        timeout && timeout > 0 ? retry : raise
      end
    end
  rescue Timeout::Error
    raise error
  end
end

PG::Connection.prepend PGConnectRetryTimeout

params = ActiveRecord::ConnectionHandling::VALID_CONN_PARAMS
if params.include? :connect_retry_timeout
  raise '???'
else
  params << :connect_retry_timeout
end