class Aws::InstanceProfileCredentials

def refresh
  credentials = MultiJson.load(get_credentials)
  @access_key_id = credentials['AccessKeyId']
  @secret_access_key = credentials['SecretAccessKey']
  @session_token = credentials['Token']
  if expires = credentials['Expiration']
    @expiration = Time.parse(expires)
  else
    @expiration = nil
  end
end