Messages are formatted in logstash's expected format.

def format_logstash_v0(self, record):
        '''
        Messages are formatted in logstash's expected format.
        '''
        host = salt.utils.network.get_fqhostname()
        message_dict = {
            '@timestamp': self.formatTime(record),
            '@fields': {
                'levelname': record.levelname,
                'logger': record.name,
                'lineno': record.lineno,
                'pathname': record.pathname,
                'process': record.process,
                'threadName': record.threadName,
                'funcName': record.funcName,
                'processName': record.processName
            },
            '@message': record.getMessage(),
            '@source': '{0}://{1}/{2}'.format(
                self.msg_type,
                host,
                self.msg_path
            ),
            '@source_host': host,
            '@source_path': self.msg_path,
            '@tags': self.tags,
            '@type': self.msg_type,
        }

        if record.exc_info:
            message_dict['@fields']['exc_info'] = self.formatException(
                record.exc_info
            )

        # Add any extra attributes to the message field
        for key, value in six.iteritems(record.__dict__):
            if key in ('args', 'asctime', 'created', 'exc_info', 'exc_text',
                       'filename', 'funcName', 'id', 'levelname', 'levelno',
                       'lineno', 'module', 'msecs', 'msecs', 'message', 'msg',
                       'name', 'pathname', 'process', 'processName',
                       'relativeCreated', 'thread', 'threadName'):
                # These are already handled above or not handled at all
                continue

            if value is None:
                message_dict['@fields'][key] = value
                continue

            if isinstance(value, (six.string_types, bool, dict, float, int, list)):
                message_dict['@fields'][key] = value
                continue

            message_dict['@fields'][key] = repr(value)
        return message_dict