Retrieving basic auth credentials from urllib2's HTTPPasswordMgr for the purpose or transparently transitioning over to requests module.

urllib2_retrieve_auth.py

"""
Assuming you have this lovely gem somewhere else in your app from the old days

..sourcecode:: python

  import urllib2

  mgr = urllib2.HTTPPasswordMgrWithDefaultRealm()
  for name, creds in services.items():  # dict of tuples: {name: (uri, user, pass)}
      mgr.add_password(None, *creds)
  auth = urllib2.HTTPBasicAuthHandler(mgr)
  opener = urllib2.build_opener(auth)
  urllib2.install_opener(opener)  # install it globally for easier access

And then the original dev throws this in right after:

..sourcecode:: python

  if 'services' in locals():
    del locals()['services']  # don't let normal code see the passwords

And now you want to use `requests`, but can't easily make the basic auth work
without risking security exposure for stuff you don't know about. So
understandably, you don't want to touch this stuff.

"""

import urllib2
import requests

class APIClient(object):
  
    # Root URL to be used for requests
      _base_url = None
  
      # The object all requests will go through provided by `requests`.
      # It will allow us to stay authenticated after the first request
      session = None
    
    def __init__(self):
        self.session = requests.Session()
        self.session.auth = self._creds
  
    @property
    def _creds(self):
        # Retrieve basic auth credentials from the depths of python
        basic_auth_handlers = [h for h in urllib2._opener.handlers
                               if isinstance(h,
                               urllib2.HTTPBasicAuthHandler)]
        available_credentials = map(lambda x: \
                                    x.passwd.find_user_password(None,
                                    cfg.site_url),
                                    basic_auth_handlers)
        # Return the first available one (if we have no credentials, it will return (None, None), so we're okay
        return available_credentials[0]