Custom JsonStreamFormatter

import json
from logging import Formatter

class JSONStreamFormatter(Formatter):
    def format(self, record):
        """
        Format the specified record as text.

        The record's attribute dictionary is used as the operand to a
        string formatting operation which yields the returned string.
        Before formatting the dictionary, a couple of preparatory steps
        are carried out. The message attribute of the record is computed
        using LogRecord.getMessage(). If the formatting string uses the
        time (as determined by a call to usesTime(), formatTime() is
        called to format the event time. If there is exception information,
        it is formatted using formatException() and appended to the message.
        """
        WHITE_LIST = [
                'threadName', 'name', 'thread', 'created', 'process', 
                'processName', 'module', 'filename', 'levelno', 
                'exc_text', 'pathname', 'lineno', 'message',
                'funcName', 'relativeCreated', 'levelname', 'msecs']
        record.message = record.getMessage()
        if self.usesTime():
            record.asctime = self.formatTime(record, self.datefmt)
        obj = {k:getattr(record, k) for k in WHITE_LIST}

        if record.exc_info:
            # Cache the traceback text to avoid converting it multiple times
            # (it's constant anyway)
            if not record.exc_text:
                record.exc_text = self.formatException(record.exc_info)
        if record.exc_text:
            try:
                obj["traceback"] = record.exc_text + ""
            except UnicodeError:
                # Sometimes filenames have non-ASCII chars, which can lead
                # to errors when s is Unicode and record.exc_text is str
                # See issue 8924.
                # We also use replace for when there are multiple
                # encodings, e.g. UTF-8 for the filesystem and latin-1
                # for a script. See issue 13232.

                obj["traceback"] = record.exc_text.decode(
                        sys.getfilesystemencoding(), 'replace')
        return json.dumps(obj)