You can set the default=
of the argument to a .get()
of os.environ
with the environment variable you want to grab.
You can also pass a 2nd argument in the .get()
call, which is the default value if .get()
doesn’t find an environment variable by that name (by default .get()
returns None
in that case).
import argparse
import os
parser = argparse.ArgumentParser(description='test')
parser.add_argument('--url', default=os.environ.get('URL'))
args = parser.parse_args()
if not args.url:
exit(parser.print_usage())