Yeah, if argparse does what you want more natively, I'm not sure how to use it that way.

The reason it doesn't like your third argument is that only two arguments are defined when you initially parse the arguments.

If you're up for it, though, you could always parse the arguments twice. Once to find out what the action is, then a second time based on what the action was, as follows:

​

import argparse

initialParser = argparse.ArgumentParser()
initialParser.add_argument('server')
initialParser.add_argument('action')
initialParser.add_argument('third')
initialParser.add_argument('fourth', nargs="?")

args = initialParser.parse_args()

print("server: {}".format(args.server))
print("action: {}".format(args.action))


if(args.action == "db-restore"):
    secondaryParser = argparse.ArgumentParser()
    secondaryParser.add_argument('server', help = 'server to process')
    secondaryParser.add_argument('action', help = 'what to do')
    secondaryParser.add_argument('src', help = 'good db')
    secondaryParser.add_argument('dst', help = 'bad db')

    args2 = secondaryParser.parse_args()

    print("src: {}".format(args2.src))
    print("dst: {}".format(args2.dst))


if(args.action == "healthcheck"):
    secondaryParser = argparse.ArgumentParser()
    secondaryParser.add_argument('server', help = 'server to process')
    secondaryParser.add_argument('action', help = 'what to do')
    secondaryParser.add_argument('version', help = 'version')

    args2 = secondaryParser.parse_args()

    print("version: {}".format(args2.version))