streaming_log.py

from io import StringIO
import logging

class StreamingLog(object):
    def __init__(self, logger_name, level=logging.INFO):
        self.stream = StringIO()
        self.handler = logging.StreamHandler(self.stream)
        formatter = logging.Formatter('%(asctime)s - %(name)s - %(levelname)s - %(message)s')
        self.handler.setFormatter(formatter)
        self.log = logging.getLogger(logger_name)
        self.log.setLevel(level)      
        self.log.addHandler(self.handler)        
    def dump(self):
        return self.stream.getvalue()
    def info(self, message):
        self.log.info(message)
    def warning(self, message):
        self.log.warning(message)
    def error(self, message):
        self.log.error(message)
    def debug(self, message):
        self.log.debug(message)

if __name__ == '__main__':
    ### EXAMPLE ###

    def my_function():
        log = StreamingLog('my_function', logging.INFO)
        log.info('info message')
        log.debug('debug message') # will not log if INFO or higher level
        log.warning('warning message')
        log.error('error message')
        response = {
            'result': 42,
            'log': log.dump()
        }
        return response

    my_function()
    # {'result': 42, 
    #  'log': '2022-03-23 09:41:58,719 - my_function - INFO - info message\n2022-03-23 09:41:58,719 - my_function - WARNING - warning message\n2022-03-23 09:41:58,719 - my_function - ERROR - error message\n'}