Python: Logging levels

You can specify a logging level using ‘logging.basicConfig’ method. Following are the built-in logging levels supported by python in ascending order.

Level	Value	Description
NOTSET	0	No logging level set.
DEBUG	10	A general debugging event.
INFO	20	An event for informational purposes.
WARNING	30	An event that might possible lead to an error.
ERROR	40	An error in the application, possibly recoverable.
CRITICAL	50	A severe error that will prevent the application from continuing.

DEBUG is the lowest built-in severity level and CRITICAL is the highest built-in severity. . If you set logging level to WARN, then it enables logging for equal/higher levels like WARNING, ERROR, CRITICAL.

import logging

logger = logging.getLogger()

def logMessages():
    logger.debug("Debug message")
    logger.info("Information Message")
    logger.warn("Warning Message")
    logger.error("Error Message")
    logger.critical("Critical Message")

if (__name__ == "__main__"):
    logMessages()

Run above program, you will get following messages.

Warning Message
Error Message
Critical Message

Observe the output, it shows only Warning, Error, Critical messages. It is because, the default level is WARNING. Update the log level to ERROR, you will get only ERROR, CRITICAL messages.

import logging

logger = logging.getLogger()
logging.basicConfig(level=logging.ERROR)

def logMessages():
    logger.debug("Debug message")
    logger.info("Information Message")
    logger.warn("Warning Message")
    logger.error("Error Message")
    logger.critical("Critical Message")

if (__name__ == "__main__"):
    logMessages()

Run above program, you will get following messages.

ERROR:root:Error Message
CRITICAL:root:Critical Message

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