Create a directory named logging and copy (or write yourself) logging_demo.py.

Part 1: Add logging to logging_demo

These exercises use the logging_demo.py file.

  1. In the file logging_demo.py complete the code for log_demo(logger).
    • Log a message using each of the 5 standard logging functions (debug, warning, info, error, critical).
    • For each log level, write a message that is a good example of what you would log at that level. Write your own message, not something from the class presentation.
  2. Run the code without any configuration of loggers. All the configuration code in the __main__ block must be commented out.
    • which log messages are printed?
    • which log messages are not printed?
    • what is the format of the output?
  3. In __main__, before calling log_demo, call basicConfig with the default values: 
    logging.basicConfig()

    Run the code.

    • which log messages are printed?
    • did the format of the output change? how different?
  4. Add a level=... parameter to the call to basicConfig to set the threshold log level to logging.DEBUG. Run the code again.
    • what is different?
  5. Complete the console_config function. The function should set:
    • log threshold is WARNING
    • log format is “{datetime} {loglevelname}: {message}”
    • log output goes to the console (the default) Run it.
    • How did the output change from previous case?
  6. Complete the file_config function. The function should use basicConfig to:
    • log threshold is DEBUG
    • log format is “{datetime} {logger_name} {loglevelname} {functionName}: {message}”
    • functionName = name of function that logged the message
    • send log messages to the file demo.log
    • modify __main__ to use file_config instead of console_config. Run the program.
    • Did it print any messages on the console? (should not)
    • Are messages logged to the file?
  7. Run it again. View the file demo.log.
    • Did the 2nd run append messages to the file or overrite the file contents? (Usually you want to append messages.)
  8. In __main__ instead of using the root logger, create a logger named “demo”. Rerun the code.
    • Can you see any changes in the log messages?

Push your final code to Github.

Part 2: Add Logging to factor.py

  1. In factor.py replace “print” statements with suitable logging statements.
  2. You should print the factors (the result) and a user-friendly message if an exception occurs.
  3. Log the exceptions in “main”, including a stacktrace (logger.exception). Print a user-friend message instead of exception.
  4. Create a function named configure() that configures the root logger so that all log messages all go to a file named factor.log.
  5. Call configure from main.
  6. Test your code.

Push your final factor.py to Github.

Integer to factor: 99
Factors of 99 are [3, 3, 11]
Integer to factor: six               <-- exception written to factor.log
Please input an integer or 0 to quit <-- user-friendly message
Integer to factor:

Logging and Log Formats

  • Python Logging Howto

  • Python Logging complete documentation for logging, with links to tutorials & cookbook. Easy to understand after you read the Logging Howto.

  • Logging Formats section lists all the things you can include in the log message format.