gae_logging.py

#
# This formatter creates log entries in this format:
# {"message": "my message", "severity": "INFO", "timestamp": {"seconds": 1518105845000, "nanos": 252}}
#


class StackdriverJSONFormatter(jsonlogger.JsonFormatter):

    FORMAT_STRING = "{message}"

    @staticmethod
    def get_timestamp_dict(when=None):
        """Converts a datetime.datetime to integer milliseconds since the epoch.

        Requires special handling to preserve microseconds.

        Args:
            when:
                A datetime.datetime instance. If None, the timestamp for 'now'
                will be used.

        Returns:
        Integer time since the epoch in milliseconds. If the supplied 'when' is
        None, the return value will be None.
        """
        if when is None:
            when = datetime.datetime.utcnow()

        ms_since_epoch = float(time.mktime(when.utctimetuple()) * 1000.0)
        return {
            'seconds': int(ms_since_epoch),
            'nanos': int(when.microsecond / 1000.0),
        }

    def add_fields(self, log_record, record, message_dict):
        super().add_fields(log_record, record, message_dict)

        log_record['severity'] = record.levelname
        log_record['timestamp'] = self.get_timestamp_dict()
        log_record['message'] = self.FORMAT_STRING.format(
            message=record.message,
            filename=record.filename,
        )