Run cloudcustodian from python with arguments

[gdisantis24]

Hello,
Currently I'm running cloudcustodian in a multi-thread environment (3 parallel execution).
To do that I'm setting:

from c7n.cli import main

def th_function(region):
      args = [
          "cc_runner",
          "run",
          "--help",
          "--region",
          region
      ]
      sys.argv = args
      main()

However I believe that multiple threads are accessing/editing sys.argv at the same time, so that's why cloud custodian sometimes is running on the same region. With my PR it's possible to run it without occurring in this problem in this way:

from c7n.cli import main
main(["run", "--help"])

[linux-foundation-easycla]

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• ✅ login: gdisantis24 / name: Giovanni Di Santi (2b9309b)

[kapilt]

we provide a parallel execution tool in c7n-org, we do internal thread parallelism as well which c7n-org is designed to work with, we do make use of thread locals, so using a naive threading wrapper has some peril. we don't really provide a stable api for use as a library vs a command line tool. that said the change seems innocuous, albeit please sign the linux foundation /cncf cla for further consideration. direct link

[gdisantis24]

Hello @kapilt , I signed the document!

[kapilt]

lgtm