Allow driver specification in AuthManager creation.

2 files changed, 20 insertions, 14 deletions

diff --git a/nova/auth/manager.py b/nova/auth/manager.py
index 7307f673b..2da53a736 100644
--- a/nova/auth/manager.py
+++ b/nova/auth/manager.py
@@ -323,25 +323,21 @@ class AuthManager(object):
     """
     _instance=None
     def __new__(cls, *args, **kwargs):
-        """Returns the AuthManager singleton with driver set
-
-        __init__ is run every time AuthManager() is called, so we need to do
-        any constructor related stuff here. The driver that is specified
-        in the flagfile is loaded here.
-        """
+        """Returns the AuthManager singleton"""
         if not cls._instance:
             cls._instance = super(AuthManager, cls).__new__(
                     cls, *args, **kwargs)
-            mod_str, sep, driver_str = FLAGS.auth_driver.rpartition('.')
-            try:
-                __import__(mod_str)
-                cls._instance.driver = getattr(sys.modules[mod_str],
-                                               driver_str)
-            except (ImportError, AttributeError):
-                raise exception.Error('Auth driver %s cannot be found'
-                                      % FLAGS.auth_driver)
         return cls._instance
 
+    def __init__(self, driver=None, *args, **kwargs):
+        """Inits the driver from parameter or flag
+
+        __init__ is run every time AuthManager() is called, so we only
+        reset the driver if it is not set or a new driver is specified.
+        """
+        if driver or not getattr(self, 'driver', None):
+           self.driver = utils.import_class(driver or FLAGS.auth_driver)
+
     def authenticate(self, access, signature, params, verb='GET',
                      server_string='127.0.0.1:8773', path='/',
                      check_type='ec2', headers=None):
diff --git a/nova/utils.py b/nova/utils.py
index a1eb0a092..0016b656e 100644
--- a/nova/utils.py
+++ b/nova/utils.py
@@ -29,11 +29,21 @@ import subprocess
 import socket
 import sys
 
+from nova import exception
 from nova import flags
 
 FLAGS = flags.FLAGS
 TIME_FORMAT = "%Y-%m-%dT%H:%M:%SZ"
 
+def import_class(import_str):
+    """Returns a class from a string including module and class"""
+    mod_str, _sep, class_str = import_str.rpartition('.')
+    try:
+        __import__(mod_str)
+        return getattr(sys.modules[mod_str], class_str)
+    except (ImportError, AttributeError):
+        raise exception.NotFound('Class %s cannot be found' % class_str)
+
 def fetchfile(url, target):
     logging.debug("Fetching %s" % url)
 #    c = pycurl.Curl()