Logging Infrastructure in Python

Posted By Rohitesh Rawat | 29-Jun-2018

We use 'print' to print a statement but it just prints to the console.
Logging allows us to instruct the program to emit information while the system is still running.
This information can be useful to us.

>>>Benefits of logging infrastructure are:

1- Multi-threading support.

2- Categorization via different levels of logging.

3-Flexibility and configurability.

4- Separation of the how from the what.

>>>Logging levels
Some of the logging levels are:

1- DEBUG: it is used when we are debugging something.
When want to write some detailed instructions on an issue that only you want to see when debugging and no other person should see that.

2- INFO: it confirms that all the things are working as expected.

3- WARNING: it indicates that something unexpected happened or may happen in the future, but the software is still working as expected.

4- ERROR: it indicates a serious problem.
The software may not able to perform some action.

>>>Logging Format: it changes the format of log messages that are displayed in the console.


import logging

logging.basicConfig(format='%(asctime)s: %(levelname)s: %(message)s',
                    datefmt='%m/%d/%Y %I:%M:%S %p',level=logging.DEBUG)
logging.warning("warning message")
logging.info("info message")
logging.error("error message")

>>>Output will be something like this:
06/03/2018 11:12:32 PM: WARNING: warning message
06/03/2018 11:12:32 PM: INFO: info message
06/03/2018 11:12:32 PM: ERROR: error message


>>>Logger Console Example:


import logging

class LoggerConsole():

    def testLog(self):
        # create logger
        logger = logging.getLogger(LoggerDemoConsole.__name__)

        # create console handler and set level to info
        consoleHandler = logging.StreamHandler()

        # create formatter
        formatter = logging.Formatter('%(asctime)s - %(name)s - %(levelname)s: %(message)s',
                    datefmt='%m/%d/%Y %I:%M:%S %p')

        # add formatter to console handler

        # add console handler to logger

        # logging messages
        logger.debug('debug message')
        logger.info('info message')
        logger.warn('warn message')
        logger.error('error message')
        logger.critical('critical message')

demo = LoggerConsole()

>>>Output will be something like this:
06/03/2018 11:12:32 PM -sample_log - INFO: info message
06/03/2018 11:12:32 PM -sample_log - WARNING: warning message
06/03/2018 11:12:32 PM -sample_log - ERROR: error message
06/03/2018 11:12:32 PM -sample_log - CRITICAL: critical message
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