# File lib/deltacloud/drivers/ec2/ec2_driver.rb, line 320
  def valid_credentials?(credentials)
    client = new_client(credentials)
    # FIXME: We need to do this call to determine if
    #        EC2 is working with given credentials. There is no
    #        other way to check, if given credentials are valid or not.
    realms = client.describe_availability_zones rescue false
    return realms ? true : false
  end