Tag: logging

Python: Create a Logger

This post is how-to create a logger.

First we need to import

import sys
import logging
from datetime import datetime
from pytz import timezone

Then we create a class for Formatter

class CustomFormatter(logging.Formatter):
    grey = "\x1b[38;20m"
    reset = "\x1b[0m"
    format = "%(asctime)s - %(name)s - %(levelname)s - %(message)s (%(filename)s:)"
    FORMATS = {
        logging.DEBUG: '\x1b[38;5;23m' + format + reset,
        logging.INFO: grey + format + reset,
        logging.WARNING: '\x1b[38;5;56m' + format + reset,
        logging.ERROR: '\x1b[38;5;197m' + format + reset,
        logging.CRITICAL: '\x1b[38;5;1m' + format +reset
    }

    def format(self, record):
        log_fmt = self.FORMATS.get(record.levelno)
        formatter = logging.Formatter(log_fmt)
        return formatter.format(record)

Then we create a function set our logger up.

def set_logger(logging_level, name, log_dir, timezone):
    LOGGING_LEVELS = ['WARNING','INFO','DEBUG','ERROR']
    if logging_level not in LOGGING_LEVELS:
        logging_level = 'INFO'

    level_lookup = {
        'WARNING': logging.WARNING,
        'INFO': logging.INFO,
        'DEBUG': logging.DEBUG,
        'ERROR': logging.ERROR,
    }
    logging.Formatter.converter = lambda *args: datetime.now(tz=timezone(timezone)).timetuple()
    logging.basicConfig(level=level_lookup[logging_level], format="[%(levelname)s] %(asctime)s - %(message)s:%(lineno)d")
    stream_handler = logging.StreamHandler(sys.stdout)
    stream_handler.setFormatter(CustomFormatter())
    logger = logging.getLogger(name)
    logger.addHandler(stream_handler)
    logger.setLevel(logging_level)

    Path(log_dir).mkdir(parents=True, exist_ok=True)

    now = datetime.now(tz=timezone(timezone))
    now = now.strftime("%H-%M-%S")

    log_file = '%slog_%s.log' % (log_dir, now)
    file_handler = logging.FileHandler(log_file, mode='a')
    file_handler.setFormatter(logging.Formatter("[%(levelname)s] %(asctime)s - %(message)s:%(lineno)d"))
    logger.addHandler(file_handler)

    return logger

References

https://alexandra-zaharia.github.io/posts/make-your-own-custom-color-formatter-with-python-logging/

Python: Logging

If you want to do some basic logging to a file, etc. You can use the logging package that comes with python. Here are some of the basic ways to log.

You first have to import the package.

import logging

You can setup your own logging configuration but for this we will just use the basic setup and log to a file.

#If you are going to have multiple handlers you should setup your handler
logging.root.handlers = []

#The file to log to
log_file = /mnt/log/

#Setup the config with the level to log up to
logging.basicConfig(filename=log_file, level=logging.INFO)

Then you setup your logger

logger = logging.getLogger('my_awesome_log')

If you want your log to truncate after a certain size then you must add the handler for truncating the log and back. If you do not use the rotatingfilehandler then the log will increase till your drive runs out of space.

handler = RotatingFileHandler(log_file, maxBytes=1024, backupCount=1)
logger.addHandler(handler)

If you also want to log to console you will need to add an additional handler for the console setting the level to log.

console = logging.StreamHandler()
console.setLevel(logging.INFO)
logger.addHandler(console)

That’s it a basic example of how to use the logging package.