Allow using nsenter for new processes (i.e. not knowing the PID) about python-nsenter

[cnelson]

So what's the ask here? You want to be able to specify a path to an arbitrary path and use the open fd to that path to enter a namespace? Something like:

with Namespace(path='/var/run/netns/foo'):
    # output network interfaces as seen from within the mypid's net NS:
    subprocess.check_output(['ip', 'a'])

Would that solve the problem?

[hjacobs]

@cnelson I just found the StackOverflow question (http://stackoverflow.com/questions/30127569/start-multiprocessing-process-in-namespace) and I think that nobody should need to copy&paste the StackOverflow code for this specific use case --- it should be possible with the "nsenter" module.

So: yes, being able to pass in the path would be one possibility (obviously keeping everything backwards compatible).

I haven't thought much about it yet...

[cnelson]

Tossed up a quick PR as it was simpler than I thought it would be -- thoughts?