Python Cli Template

cli.py

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

"""
This console application description

EXAMPLE:

    python3 {}
""".format(__file__)

__author__ = "posilva@gmail.com"
__version__ = "0.1.0"
__date__ = "2020-11-06"

__version_text__ = "(version {version} [{date}])".format(
    version=__version__, date=__date__)
__epilog__ = "{author} {version}".format(
    author=__author__, version=__version_text__)


import argparse
import os
import getpass
import logging
import sys

def exit(msg, *args, **kwargs):
    logging.fatal(msg, *args, **kwargs)
    sys.exit(1)

    
def from_arg_or_env(arg, env_var, arg_name):
    if arg is None:
        logging.debug("'{}' argument missing, fetching from environment variable '{}' ".format(arg_name, env_var))
        if os.environ.get(env_var) is None:
            exit("failed to fetch '{}' from enviroment variable '{}'".format(arg_name, env_var))
        else:
            return os.environ.get(env_var)
    return arg


def from_env_or_ask(env_key, secure=False):
    prompt = "Enter {text}: ".format(text=env_key)
    if os.environ.get(env_key) is None:
        if (secure):
            return getpass.getpass(prompt=prompt)
        else:
            return input(prompt)


def add_arg(parser, longname, help, action="store", required=True, short=None, default=None):
    s = longname[0:]
    if short is not None:
        s = short

    import re
    longname = re.sub('[ -]', '_', longname)

    parser.add_argument(
        "-{}".format(s),
        "--{}".format(longname),
        action=action,
        dest=longname,
        required=required,
        default=default,
        help=help)
    
#################################################################
#    DO SOME WORK START HERE
#################################################################
def add_custom_args(parser):
    '''
        Add here the custom args for this cli app
    '''
    add_arg(parser, "arg", "arg_var", required=False, short="a")
    
def do_work(args):
    logging.debug("doing some work")

#################################################################
#    DO SOME WORK END 
#################################################################

def main(args):
    log_level = logging.DEBUG if args.verbose > 0 else logging.ERROR
    logging.basicConfig(level=log_level)
    logging.debug("processing with args: ini: {}".format(args))    
    do_work(args)


if __name__ == "__main__":

    parser = argparse.ArgumentParser(
        description=__doc__,
        formatter_class=argparse.RawDescriptionHelpFormatter,
        epilog=__epilog__)

    add_custom_args(parser)
    

    parser.add_argument(
        "-v",
        "--verbose",
        action="count",
        default=0,
        help="Verbosity (-v, -vv, etc)")

    parser.add_argument(
        "--version",
        action="version",
        version="%(prog)s {version_text}".format(
            version_text=__version_text__))

    args = parser.parse_args()
    main(args)