database_check.rb

class DatabaseCheck
  def self.wait_for_connection
    self.new.check(10)
  end
  def check(times)
    times.times do
      opts = Rails.configuration.database_configuration[Rails.env]
      ActiveRecord::Base.establish_connection (opts)
      connected = begin
                    ActiveRecord::Base.connection_pool.with_connection { |con| con.active? }
                  rescue => e
                    last_message = "#{e.class.name}: #{e.message}"
                    false
                  end
      printf '.'
      return true if connected
      sleep 1
    end

    false
  end
end