python argparse: use arguments as values for a list

Question

I've google'd quite a bit, and read the argparse documentation that I think suggests using something with vars(). I get the Namespace violation as expected, I just cant figure out the path around this issue.

Essentially, I would like to take an argparse multi-value argument and create a list from those values so I can run a for-loop through them. This is to interface with our VNX array to reset the data snapshot on all the Developer environments.

When I run the command I can see the argparse is getting the values correctly, but its throwing the Namespace exception and not actually using the values for the argument.

Much appreciation for any guidance, even a link to some better docs that will explain my problem better. I know the issue, and how I want to fix it, I'm just not sure what to even read(or google) to get around this syntax-wise?

This is what I get when i run the code:

[[email protected] tmp]# ./envrestore.py -e dev1 dev2 dev3

Namespace(myenv=['dev1', 'dev2', 'dev3'])

Traceback (most recent call last): File "./envrestore.py", line 43, in run_create_snap() File "./envrestore.py", line 36, in run_create_snap for e in myenv: TypeError: 'Namespace' object is not iterable

[[email protected] tmp]#

#!/usr/bin/env python

import pexpect, sys, datetime, argparse, time
from fabric.api import *

parser = argparse.ArgumentParser()
parser.add_argument('-e', '--myenv', nargs='*', type=str)
print parser.parse_args()

array = "vnx.lipsum.com"
seckey = "/opt/Navisphere/blah"
myenv = parser.parse_args()
dbhosts = ['mongo01', 'mysql01']

# !! DO NOT CHANGE IDs !!
lunpnum = "0000000"
mongo_plunid = "3"
mysql_plunid = "4"

def delete_snap(env=myenv, host=dbhosts):
    child = pexpect.spawn('naviseccli -secfilepath %s -h %s snap -destroy -id %s-%s-snap' % (seckey, array, host, env))
    print child
    child.logfile = sys.stdout
    child.expect('Are you sure you want to perform this operation\?\(y\/n\):')
    child.sendline('n')

def create_snap(env=myenv, host=dbhosts, lunid=''):
    print "naviseccli -secfilepath %s -h %s snap -create -res %s -name %s-%s-snap -allowReadWrite yes" % (seckey, array, lunid, host, env)

def run_delete_snap():
    for e in myenv:
      for h in dbhosts:
        delete_snap(env=e, host=h)

def run_create_snap():
    for e in myenv:
      for h in dbhosts:
        if "mysql" in h:
          create_snap(env=e, host=h, lunid=mysql_plunid)
        elif "mongo" in h:
          create_snap(env=e, host=h, lunid=mongo_plunid)

run_create_snap()

Jblasco · Accepted Answer · 2013-07-21 17:03:24Z

1

I believe the problem is in what you are passing as myenv:

myenv = parser.parse_args()

I think you mean

myenv = parser.parse_args().myenv

Cheers!

answered Jul 21, 2013 at 17:03

Jblasco

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jed Over a year ago

Thanks very much , that did the trick. [[email protected] tmp]# ./envrestore.py -e dev1 naviseccli -secfilepath /opt/Navisphere/blah -h vnx.lipsum.com snap -create -res 3 -name mongo01-dev1-snap -allowReadWrite yes naviseccli -secfilepath /opt/Navisphere/blah -h vnx.lipsum.com snap -create -res 4 -name mysql01-dev1-snap -allowReadWrite yes

unutbu · Accepted Answer · 2013-07-21 17:02:00Z

1

myenv is the argparse.Namespace instance itself. To get the values in the option named myenv, use myenv.myenv.

for e in myenv.myenv:
    print(e)

Or, to make the code clearer, name the Namespace something else:

args = parser.parse_args()
for e in args.myenv:
   ...

answered Jul 21, 2013 at 17:02

unutbu

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1 Comment

jed Over a year ago

Thanks so much, always something so simple - and without your help i don't think I would have figured that out. Your method works perfectly. However, I went with Jblasco's below since it allows me to keep the for loop cleaner. Thanks again so much!

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