AWS Lambda Python Log Factory w/ Filter Secrets

__init__.py

'''
Place this file in your lambda package next to the handler file.

Setting the log formatter on lambda loses the request id out of the context.
But, you often want to use a logger across a few files and name them
or change the log format. 

This factory will ensure that the lambda context id is available to any
log format you choose. It also has the ability to filter out strings
from the logs using a regular expression.
```
import logging

from . import log_factory

LOGGER = logging.getLogger(__name__)
def handler(event, context):
    '''lambda handler'''
    log_factory(context)
    LOGGER.info('formatted logger with a secret password: %s', 'abcdefg')
    # [INFO] 2020-12-11T22:47:37.043Z adfadfdsfasdf __init__.py formatted logger with a secret password: ****
```
'''
import os
import re
import sys
import uuid
import logging

def log_factory(context):
    '''
    Return a log formatter with the request id added
    '''
    old_factory = logging.getLogRecordFactory()
    _id = str(uuid.uuid4())
    def aws_request_id(*args, **kwargs):
        record = old_factory(*args, **kwargs)
        try:
            record.aws_request_id = context.aws_request_id
        except AttributeError:
            # Request ID is unset. Use our own unique id
            record.aws_request_id = _id
        return record
    logging.setLogRecordFactory(aws_request_id)

class Filter():
    '''Filter hides information in logs'''
    def __init__(self, formatter, patterns):
        self.formatter = formatter
        self.__patterns = patterns

    def format(self, record):
        '''format and filter our logs'''
        msg = self.formatter.format(record)
        for pattern in self.__patterns:
            msg = pattern.sub('****', msg)
        return msg

    def __getattr__(self, attr):
        return getattr(self.formatter, attr)

# Own format
FORMAT = "[%(levelname)s]\t%(asctime)s.%(msecs)dZ\t%(aws_request_id)s\t%(name)s\t%(message)s\n"
FILTERS = [
    # Filter these strings / regex from logs automatically
    re.compile(r'abcdefg'),
]
LOGGER = logging.getLogger()
for hander in LOGGER.handlers:
    hander.setFormatter(Filter(logging.Formatter(FORMAT), FILTERS))
LOGGER.setLevel(os.getenv('LOG_LEVEL', 'INFO'))
logging.getLogger('boto3').setLevel(logging.ERROR)
logging.getLogger('botocore').setLevel(logging.ERROR)