docs: def publish(self, metrics, config):
          """Publishes metrics to a file in JSON format.
  
          This method is called by the Snap deamon during the collection phase
          of the execution of a Snap workflow.
  
          In this example we are writing the metrics to a file in json format.
          We obtain the path to the file through the config (`ConfigMap`) arg.
  
          Args:
              metrics (obj:`list` of :obj:`snap_plugin.v1.Metric`):
                  List of metrics to be collected.
  
          Returns:
              :obj:`list` of :obj:`snap_plugin.v1.Metric`:
                  List of collected metrics.
          """
          if len(metrics) > 0:
              with open(config["file"], 'a') as outfile:
                  for metric in metrics:
                      outfile.write(
                          json_format.MessageToJson(
                              metric._pb, including_default_value_fields=True))