logger_.py

#!/usr/bin/env python3
# -*- coding: utf-8 -*-

# -------------------------------------------------------------------------------
#                                                                               -
#  Python dual-logging setup (console and log file),                            -
#  supporting different log levels and colorized output                         -
#                                                                               -
#  Created by Fonic <https://github.com/fonic>                                  -
#  Date: 04/05/20                                                               -
#                                                                               -
#  Based on:                                                                    -
#  https://stackoverflow.com/a/13733863/1976617                                 -
#  https://uran198.github.io/en/python/2016/07/12/colorful-python-logging.html  -
#  https://en.wikipedia.org/wiki/ANSI_escape_code#Colors                        -
#                                                                               -
# -------------------------------------------------------------------------------

import os
import sys
import logging


# Logging formatter supporting colored output
class LogFormatter(logging.Formatter):
    COLOR_CODES = {
        logging.CRITICAL: "\033[1;35m",  # bright/bold magenta
        logging.ERROR: "\033[1;31m",  # bright/bold red
        logging.WARNING: "\033[1;33m",  # bright/bold yellow
        logging.INFO: "\033[0;37m",  # white / light gray
        logging.DEBUG: "\033[1;30m"  # bright/bold black / dark gray
        }

    RESET_CODE = "\033[0m"

    def __init__(self, color, *args, **kwargs):
        super(LogFormatter, self).__init__(*args, **kwargs)
        self.color = color

    def format(self, record, *args, **kwargs):
        if self.color is True and record.levelno in self.COLOR_CODES:
            record.color_on = self.COLOR_CODES[record.levelno]
            record.color_off = self.RESET_CODE
        else:
            record.color_on = ""
            record.color_off = ""
        return super(LogFormatter, self).format(record, *args, **kwargs)


# Setup logging
def setup_logging(console_log_output, console_log_level, console_log_color, logfile_file, logfile_log_level,
                  logfile_log_color, log_line_template):
    # Create logger
    # For simplicity, we use the root logger, i.e. call 'logging.getLogger()'
    # without name argument. This way we can simply use module methods for
    # for logging throughout the script. An alternative would be exporting
    # the logger, i.e. 'global logger; logger = logging.getLogger("<name>")'
    logger = logging.getLogger()

    # Set global log level to 'debug' (required for handler levels to work)
    logger.setLevel(logging.DEBUG)

    # Create console handler
    console_log_output = console_log_output.lower()
    if console_log_output == "stdout":
        console_log_output = sys.stdout
    elif console_log_output == "stderr":
        console_log_output = sys.stderr
    else:
        print("Failed to set console output: invalid output: '%s'" % console_log_output)
        return logger

    console_handler = logging.StreamHandler(console_log_output)

    # Set console log level
    try:
        console_handler.setLevel(console_log_level.upper())  # only accepts uppercase level names
    except:
        print("Failed to set console log level: invalid level: '%s'" % console_log_level)
        return logger

    # Create and set formatter, add console handler to logger
    console_formatter = LogFormatter(fmt=log_line_template, color=console_log_color)
    console_handler.setFormatter(console_formatter)
    logger.addHandler(console_handler)

    # Create log file handler
    try:
        logfile_handler = logging.FileHandler(logfile_file)
    except Exception as exception:
        print("Failed to set up log file: %s" % str(exception))
        return logger

    # Set log file log level
    try:
        logfile_handler.setLevel(logfile_log_level.upper())  # only accepts uppercase level names
    except:
        print("Failed to set log file log level: invalid level: '%s'" % logfile_log_level)
        return logger

    # Create and set formatter, add log file handler to logger
    logfile_formatter = LogFormatter(fmt=log_line_template, color=logfile_log_color)
    logfile_handler.setFormatter(logfile_formatter)
    logger.addHandler(logfile_handler)

    # Success
    return logger


def get_logger():
    script_name = os.path.splitext(os.path.basename(sys.argv[0]))[0]
    return setup_logging(console_log_output="stdout", console_log_level="info", console_log_color=True,
                         logfile_file=script_name + ".log", logfile_log_level="debug", logfile_log_color=False,
                         log_line_template="%(color_on)s[%(asctime)s] [%(threadName)s] [%(levelname)-8s] %(message)s%(color_off)s")


logger = get_logger()