main.py

#!/usr/bin/env python

import sys
import argparse
from ruamel.yaml import YAML
import logging.config
from pythonjsonlogger import jsonlogger

FORMAT = "[%(asctime)s %(levelname)-5s|%(name)s|%(filename)20s:%(lineno)-3s|%(funcName)20s()] %(message)s"
logger = logging.getLogger(__name__)


class Main:
    """ might as well use a class. It'll make things easier later. """

    def __init__(self, args=False):
        """ init method, run at class creation """
        self.args = args

    def run(self):
        """ do stuff here """
        logger.info("info-level log message")
        logger.debug("debug-level log message")
        logger.error("error-level log message")
        print("run.")

def read_yaml(file_path: str) -> dict:
    yaml = YAML(typ='safe')
    with open(file_path, 'r') as f:
        return yaml.load(f)

def configure_logging(logging_config_file=None, verbose=False, log_file=None):
    """
    The logs are configured from the configuration file in yaml.
    If no configuration file is provided, a basic configuration is performed.
    Likewise, if verbose is true, the default level of the logger is changed to DEBUG.
    """

    if logging_config_file:
        # noinspection PyBroadException
        try:
            logging_conf = read_yaml(logging_config_file)
        except Exception:
            print(f"Cannot read file {logging_config_file}. Configuring default logging")
        else:
            if log_file:
                logging_conf['handlers']['file']['filename'] = log_file
            logging.config.dictConfig(logging_conf)
            if verbose:
                level_by_config = logging.getLogger().getEffectiveLevel()
                logging.getLogger().setLevel(min(level_by_config, logging.DEBUG))
            return logging_conf
    logging.basicConfig(filename=log_file, format=FORMAT,
                        level=logging.DEBUG if verbose else logging.INFO)
    return None

def parse_args(argv):
    """
    parse arguments/options
    """
    p = argparse.ArgumentParser(description='App description')
    p.add_argument('-v', '--verbose', dest='verbose', action='count', default=0,
                   help='verbose output. specify twice for debug-level output.')
    p.add_argument("-c", "--config", action="store", dest="input_config_file",
                   help="Path to the configuration file.", default=None)

    args = p.parse_args(argv)

    return args


if __name__ == "__main__":
    args = parse_args(sys.argv[1:])
    configure_logging(args.input_config_file)

    if args.verbose > 1:
        logger.setLevel(logging.DEBUG)
    elif args.verbose > 0:
        logger.setLevel(logging.INFO)
    main = Main(args)
    main.run()