code: def get_primary_mac_address():
      
      log = logging.getLogger(mod_logger + '.get_primary_mac_address')
      log.debug('Attempting to determine the MAC address for eth0...')
      try:
          mac_address = netifaces.ifaddresses('eth0')[netifaces.AF_LINK][0]['addr']
      except Exception:
          _, ex, trace = sys.exc_info()
          msg = '{n}: Unable to determine the eth0 mac address for this system:\n{e}'.format(
              n=ex.__class__.__name__, e=str(ex))
          raise AWSMetaDataError, msg, trace
      return mac_address
docs: Determines the MAC address to use for querying the AWS
      meta data service for network related queries
  
      :return: (str) MAC address for the eth0 interface
      :raises: AWSMetaDataError