Python Logger

cat <<'EOF'> config.py
LOGGER_MAX_FILE_LENGTH = 10
EOF

mkdir src
cat <<'EOF'> src/logger.py
import logging
import datetime
import sys

from config import *

if isinstance(LOGGER_MAX_FILE_LENGTH, int):
    LOGGER_MAX_FILE_LENGTH = str(LOGGER_MAX_FILE_LENGTH)


def get_now() -> str:
    #
    # choose your format
    #
    current_time = datetime.datetime.now()

    # 2023-07-16 22:16:15.958
    formatted_time_1 = current_time.strftime("%Y-%m-%d %H:%M:%S.%f")[:-3]

    # 22:16:54.471
    formatted_time_2 = current_time.strftime("%H:%M:%S.%f")[:-3]

    # 22:17:21
    formatted_time_3 = current_time.strftime("%H:%M:%S")

    return formatted_time_2


class ExitOnCriticalHandler(logging.Handler):
    def emit(self, record):
        # Unset Color
        COLOR = RESET = "\033[0m"

        # Debug -> Black
        if record.levelno == logging.DEBUG:
            COLOR = "\033[0m"
        # Info -> Green
        elif record.levelno == logging.INFO:
            COLOR = "\033[92m"
        # Warn -> Blue
        elif record.levelno == logging.WARNING:
            COLOR = "\033[94m"
        # Error -> Orange
        elif record.levelno == logging.ERROR:
            COLOR = "\033[38;5;208m"
        # Critical -> Red
        elif record.levelno >= logging.CRITICAL:
            COLOR = "\033[91m"

        # Custom Line
        print(
            COLOR
            + "{:} {:} {:04} {:{w}} {:}".format(
                get_now(),
                record.levelname,
                record.lineno,
                record.filename,
                record.msg,
                w=LOGGER_MAX_FILE_LENGTH,
            )
            + RESET
        )

        # Exit on Critical
        if record.levelno >= logging.CRITICAL:
            logging.shutdown()
            print("\033[91m" + "GOT A CRITICAL -> EXIT HERE!" + "\033[0m")
            sys.exit()


# Init Logger
logger = logging.getLogger()
logger.setLevel(logging.INFO)

# Create and add the custom handler
exit_handler = ExitOnCriticalHandler()
logger.addHandler(exit_handler)


# Set Log Level
def set_log_level(level: str):
    # Parse/ Set LogLevel
    if level.lower() in ["d", "debug"]:
        logger.setLevel(logging.DEBUG)
    elif level.lower() in ["i", "info"]:
        logger.setLevel(logging.INFO)
    elif level.lower() in ["w", "warning"]:
        logger.setLevel(logging.WARNING)
    elif level.lower() in ["e", "error"]:
        logger.setLevel(logging.ERROR)
    elif level.lower() in ["c", "critical"]:
        logger.setLevel(logging.CRITICAL)

    # Custom level name mappings, Debug -> D
    logging.addLevelName(logging.DEBUG, "D")
    logging.addLevelName(logging.INFO, "I")
    logging.addLevelName(logging.WARNING, "W")
    logging.addLevelName(logging.ERROR, "E")
    logging.addLevelName(logging.CRITICAL, "C")


# Functions to Call
def ldebug(msg: str):
    logger.debug(msg)


def linfo(msg: str):
    logger.info(msg)


def lwarning(msg: str):
    logger.warning(msg)


def lerror(msg: str):
    logger.error(msg)


def lcritical(msg: str):
    logger.critical(msg)
EOF

cat <<'EOF'> main.py
from src.logger import *
from argparse import ArgumentParser

# Main
if __name__ == "__main__":
    parser = ArgumentParser(description="My Custom Logger Example")
    parser.add_argument(
        "-ll",
        "--loglevel",
        type=str,
        default="DEBUG",
        choices=[
            "d",
            "DEBUG",
            "i",
            "INFO",
            "w",
            "WARNING",
            "e",
            "ERROR",
            "c",
            "CRITICAL",
        ],
        help="Set the logging level",
    )
    args = parser.parse_args()
    print("set log level to:", args.loglevel)
    set_log_level(level=args.loglevel)

    # This get's always printed
    print("This is output to the console")

    # Example Logs, incl. Critical
    ldebug("This is for debugging. Very talkative!")
    linfo("This is for normal chatter")
    lwarning("Warnings should almost always be seen.")
    lerror("You definitely want to see all errors!")
    lcritical("Last message before a program crash!")
EOF

user@host $ python3 main.py
set log level to: DEBUG
This is output to the console
22:51:03.673 D 0105 logger.py  This is for debugging. Very talkative!
22:51:03.673 I 0109 logger.py  This is for normal chatter
22:51:03.673 W 0113 logger.py  Warnings should almost always be seen.
22:51:03.673 E 0117 logger.py  You definitely want to see all errors!
22:51:03.673 C 0121 logger.py  Last message before a program crash!
GOT A CRITICAL -> EXIT HERE!

user@host $ python3 main.py -ll w
set log level to: w
This is output to the console
22:56:39.721 W 0113 logger.py  Warnings should almost always be seen.
22:56:39.721 E 0117 logger.py  You definitely want to see all errors!
22:56:39.721 C 0121 logger.py  Last message before a program crash!
GOT A CRITICAL -> EXIT HERE!