adding logging notes, files

Author: pauldevos

logging.txt

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+07/28/2021 09:37:19 - root - WARNING - this is a warning message
+07/28/2021 09:37:19 - root - ERROR - this is an error message
+07/28/2021 09:37:19 - root - CRITICAL - this is a critical message
+07/28/2021 09:37:55 - root - DEBUG - This is a debug message
+07/28/2021 09:37:55 - root - INFO - This is an info message
+07/28/2021 09:37:55 - root - WARNING - this is a warning message
+07/28/2021 09:37:55 - root - ERROR - this is an error message
+07/28/2021 09:37:55 - root - CRITICAL - this is a critical message

logging/README.md

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+# Logging
+
+### Can use a ConfigFile
+
+logging.conf or logging.ini
+
+```python
+import logging.config
+
+logging.config.fileConfig('logging.config')
+
+
+```
+
+```python
+import logging.config
+
+logging.config.dictConfig('logging.config')
+
+```
+
+### Capturing Stacktraces

logging/exceptions.py

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+import logging
+import traceback
+
+try:
+    a = [1,2,3]
+    val = a[4]
+except Exception as e:
+    #logging.error(e, exc_info=True)
+    logging.error(f"The Error is: {traceback.format_exc()}")

logging/helper.py

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+import logging
+
+logging.basicConfig(level=logging.DEBUG, filename='logging.txt', 
+                    filemode='a',
+                    format="%(asctime)s - %(name)s - %(levelname)s - %(message)s",
+                    datefmt='%m/%d/%Y %H:%M:%S'
+                    )
+
+
+logging.debug("This is a debug message")
+logging.info("This is an info message")
+# these logged by default, can set a level higher like debug if desired.
+logging.warning("this is a warning message")
+logging.error("this is an error message")
+logging.critical("this is a critical message")

logging/main.py

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+import logging
+
+# grabs the name of the file for the log message
+# good practice to add to all modules
+logger = logging.getLogger(__name__)
+
+# create handler
+stream_handler = logging.StreamHandler()
+file_handler = logging.FileHandler('file.log')
+
+# set level and format
+stream_handler.setLevel(logging.WARNING)
+file_handler.setLevel(logging.ERROR)
+
+formatter = logging.Formatter('%(name)s - %(levelname)s - %(message)s')
+stream_handler.setFormatter(formatter)
+file_handler.setFormatter(formatter)
+
+logger.addHandler(stream_handler)
+logger.addHandler(file_handler)
+
+logger.warning("This is a warning")
+logger.error("This is an error")

logging/rotatinghandlers.py

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+import logging
+# https://docs.python.org/3/library/logging.handlers.html
+from logging.handlers import RotatingFileHandler, TimedRotatingFileHandler
+import time
+
+logger  = logging.getLogger(__name__)
+logger.setLevel(logging.INFO)
+
+# roll over after 2KB, and keep backup logs...
+handler_size = RotatingFileHandler('app.log', mode='a', maxBytes=2000, backupCount=5)
+
+# when: s, m, h, d, midnight, w0
+handler_time = TimedRotatingFileHandler('timed_log.log', when='s', interval=5, backupCount=5)
+
+
+logger.addHandler(handler_time)
+
+for _ in range(20):
+    time.sleep(1)
+    logger.info("This is some text, watch it pile up over time.")