def load_environment_vars():
  """Loads the environment information receivedfrom dockers
  boostrap_servers, backend, control_topic
  Returns:
      boostrap_servers (str): list of boostrap server for the Kafka connection
      backend (str): hostname of the backend
      control_topic (str): name of the control topic
  """
  bootstrap_servers = os.environ.get('BOOTSTRAP_SERVERS')
  backend = os.environ.get('BACKEND')
  control_topic = os.environ.get('CONTROL_TOPIC')

  return (bootstrap_servers, backend, control_topic)

if __name__ == '__main__':
  try:
    logging.basicConfig(
          stream=sys.stdout,
          level=logging.INFO,
          format='%(asctime)s.%(msecs)03d %(levelname)s %(module)s: %(message)s',
          datefmt='%Y-%m-%d %H:%M:%S')

    bootstrap_servers, backend, control_topic = load_environment_vars()
    """Loads the environment information"""

    logging.info("Received environment information (bootstrap_servers, backend, control_topic, control_topic) ([%s], [%s], [%s])", 
              bootstrap_servers, backend, control_topic)
    
    consumer = KafkaConsumer(control_topic, enable_auto_commit=False, bootstrap_servers=bootstrap_servers, group_id='logger')
    """Starts a Kafka consumer to receive the datasource information from the control topic"""
    
    url = 'http://'+backend+'/datasources/' 
    logging.info("Created and connected Kafka consumer for control topic")

    for msg in consumer:
        """Gets a new message from Kafka control topic"""
        logging.info("Message received in control topic")
        logging.info(msg)
        try:
          deployment_id = int.from_bytes(msg.key, byteorder='big')
          """Whether the deployment ID received matches the received in this task, then it is a datasource for this task."""
            
          data = json.loads(msg.value)
          """ Data received from Kafka control topic. Data is a JSON with this format:
              dic={
                  'topic': ..,
                  'input_format': ..,
                  'input_config' : ..,
                  'validation_rate' : ..,
                  'total_msg': ..
                  'description': ..,
              }
          """
          
          retry = 0
          data['deployment'] = str(deployment_id)
          data['input_config'] = json.dumps(data['input_config'])
          data['time'] = datetime.datetime.utcfromtimestamp(msg.timestamp/1000.0).strftime("%Y-%m-%dT%H:%M:%S%Z")
          ok = False
          logging.info("Sending datasource to backend: [%s]", data)
          while not ok and retry < RETRIES:
            try:
              request = Request(url, json.dumps(data).encode(), headers={'Content-type': 'application/json'})
              with urlopen(request) as resp:
                res = resp.read()
                ok = True
                resp.close()
              logging.info("Datasource sent to backend!!")

              consumer.commit()
              """commit the offset to Kafka after sending the data to the backend"""
            
            except Exception as e:
              retry+=1
              time.sleep(SLEEP_BETWEEN_REQUESTS)
              logging.error("Error sending data to the backend [%s]. Try again in [%d]s.", str(e), SLEEP_BETWEEN_REQUESTS)

        except Exception as e:
          logging.error("Error with the received datasource [%s]. Waiting for new data.", str(e))
  except Exception as e:
          traceback.print_exc()
          logging.error("Error in main [%s]. Component will be restarted.", str(e))