Add logging session materials

session_6_logging/.gitignore

+my.log

session_6_logging/README.md

+# Logging
+
+## Usage
+
+    python intro_logging.py
+
+or
+
+    python -m intro_logging
+
+and with the current configuration you should see the output being saved to a
+file `my.log` as well as printed to the console.
+
+Edit `logging.conf` and re-run `intro_logging.py` to see how logged messages
+get sent to different destinations depending on the order of loggers, their
+level, propagate status and qualname.
+
+
+## Useful links
+
+* [logging HOWTO](https://docs.python.org/howto/logging.html) - from beginner to advanced
+* [logging cookbook](https://docs.python.org/howto/logging-cookbook.html)
+* [`logging`](https://docs.python.org/library/logging.html)
+* [`logging.config`](https://docs.python.org/library/logging.config.html) - the many ways to configure the logging module
+* [`logging.handlers`](https://docs.python.org/library/logging.handlers.html) - different ways to handle logging output

session_6_logging/intro_logging.py

+# -*- coding: utf-8 -*-
+
+import logging
+import logging.config
+
+
+# Using a basic configuration
+# logging.basicConfig(format="%(asctime)s %(levelname)-8s %(pathname)s: %(message)s",
+#                     level=logging.DEBUG)
+#
+
+# or a configuration file to assist and allow customization
+logging.config.fileConfig("logging.conf")
+
+# more on configuring logging at:
+# https://docs.python.org/howto/logging.html#configuring-logging
+
+# Logs can be sent to different destinations, not just the console output
+# You could send to a log server, a file, a different process, via email...
+#
+# For different handlers see:
+# https://docs.python.org/library/logging.handlers.html
+
+# The name passed to getLogger() can be used in logging.conf's qualname
+# attribute to target the output of a specific logger
+LOG = logging.getLogger(__name__)
+
+
+def main():
+    # Logging uses an implicit severity level
+    # See: https://docs.python.org/library/logging.html#logging-levels
+    # CRITICAL
+    # ERROR
+    # WARNING
+    # INFO
+    # DEBUG
+    LOG.critical("HAAA!!! (running around with hands in the air!)")
+    LOG.error("OOPS!!")
+
+    # variables can be passed using %s as placeholder
+    variable = ("Bob", "is", "here")
+    LOG.warning("WARN: %s %s %s!!", *variable)
+
+    LOG.info("This is info")
+    LOG.debug("More verbosity")
+
+    other()
+
+
+def other():
+    try:
+        1 / 0
+    except ZeroDivisionError:
+        LOG.exception("We shouldn't get zeros here")
+
+    LOG.critical("But life goes on")
+
+
+if __name__ == "__main__":
+    main()

session_6_logging/logging.conf

+# Here you need at least one logger, one handler and one formatter
+
+[loggers]
+# The order defined here and in other sections is important
+# messages flow from right to left
+keys=root,file_log
+
+[handlers]
+keys=console,file
+
+[formatters]
+keys=my_formatter
+
+[formatter_my_formatter]
+# For additional formatting keywords see:
+# https://docs.python.org/library/logging.html#logrecord-attributes
+# The negative number next to the keywords defines white space padding
+format=%(asctime)s %(levelname)-8s %(funcName)-5s %(pathname)s: %(message)s
+
+[handler_console]
+# For different types of handlers see:
+# https://docs.python.org/library/logging.handlers.html
+class=StreamHandler
+level=DEBUG
+formatter=my_formatter
+# The order of arguments here corresponds to the arguments of StreamHandler
+args=(sys.stdout,)
+
+[handler_file]
+# For different types of handlers see:
+# https://docs.python.org/library/logging.handlers.html
+class=FileHandler
+level=DEBUG
+formatter=my_formatter
+# The order of arguments here corresponds to the arguments of FileHandler
+# Use 'a' to preserve the logfile across executions and 'w' to empty the logfile
+args=("my.log", 'w',)
+
+[logger_root]
+level=DEBUG
+handlers=console
+
+[logger_file_log]
+level=DEBUG
+handlers=file
+# if propagate=0 messages are used and consumed by the current logger
+# if propagate=1 they are used and passed to the next logger
+propagate=1
+# qualname restricts the current logger to only handle output of one target.
+# The target name is specified in logging.getLogger("target")
+qualname=__main__

session_6_logging/main.py

+# -*- coding: utf-8 -*-
+
+print(__name__)
+
+# vim: ai sts=4 et sw=4