Part 1: Add logging to logging_demo

These exercises use the logging_demo.py file.

1. Complete the code for function log_demo(logger).
   • Log one message using each of the 5 standard logging functions (debug, warning, info, error, critical or fatal).
   • 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).
   • which log messages are printed?
   • which log messages are not printed?
3. In __main__, invoke basicConfig() to initialize the logging facility, then call log_demo.
   • This causes basicConfig to use default values for all settings.
   • You must call this before any other logging calls, or it has no effect.

     if __name__ == `__main__`:
       # basic config with default settings
       logging.basicConfig()
     
       logger = logging.getLogger()
       log_demo(logger)
     

     Run the code.

   • what changed?
   • what do the fields in the output messages mean?
4. Create a named logger instead the default (root) logger. In __main__:

    logger = logging.getLogger("demo")
   

   Run the code.

   • how does the output change?
5. In __main__ add a level=... parameter to the call to basicConfig to set the threshold log level to logging.DEBUG.

       logging.basicConfig(level=...)
   

   Run the code again.

   • what does level=n do?
   • what is the datatype of the level value? (int, str, something else?)
   • Can you use level=15? level="DEBUG"?
6. 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)

   Modify main again:

   • Remove call to basicConfig.
   • Invoke console_config instead.

   Run it.

   • How did the output change from previous case?
7. Complete the file_config function. The function should use basicConfig to:
   • set 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 a file named demo.log
   • modify __main__ to invoke 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?
8. If you run the code several times, what happens to the file demo.log? Does each run append messages to the file or overrite the old contents?
   • Does this make sense?

Push your final code to Github Classroom.

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.