This branch allows LdapDriver to reconnect to LDAP server if connection is lost.

nova/auth/fakeldap.py

@@ -100,6 +100,11 @@ class OBJECT_CLASS_VIOLATION(Exception):  # pylint: disable=C0103
     pass
 
 
+class SERVER_DOWN(Exception):  # pylint: disable=C0103
+    """Duplicate exception class from real LDAP module."""
+    pass
+
+
 def initialize(_uri):
     """Opens a fake connection with an LDAP server."""
     return FakeLDAP()
@@ -202,25 +207,38 @@ def _to_json(unencoded):
     return json.dumps(list(unencoded))
 
 
+server_fail = False
+
+
 class FakeLDAP(object):
     """Fake LDAP connection."""
 
     def simple_bind_s(self, dn, password):
         """This method is ignored, but provided for compatibility."""
+        if server_fail:
+            raise SERVER_DOWN
         pass
 
     def unbind_s(self):
         """This method is ignored, but provided for compatibility."""
+        if server_fail:
+            raise SERVER_DOWN
         pass
 
     def add_s(self, dn, attr):
         """Add an object with the specified attributes at dn."""
+        if server_fail:
+            raise SERVER_DOWN
+
         key = "%s%s" % (self.__prefix, dn)
         value_dict = dict([(k, _to_json(v)) for k, v in attr])
         Store.instance().hmset(key, value_dict)
 
     def delete_s(self, dn):
         """Remove the ldap object at specified dn."""
+        if server_fail:
+            raise SERVER_DOWN
+
         Store.instance().delete("%s%s" % (self.__prefix, dn))
 
     def modify_s(self, dn, attrs):
@@ -232,6 +250,9 @@ class FakeLDAP(object):
             ([MOD_ADD | MOD_DELETE | MOD_REPACE], attribute, value)
 
         """
+        if server_fail:
+            raise SERVER_DOWN
+
         store = Store.instance()
         key = "%s%s" % (self.__prefix, dn)
 
@@ -255,6 +276,9 @@ class FakeLDAP(object):
         fields -- fields to return. Returns all fields if not specified
 
         """
+        if server_fail:
+            raise SERVER_DOWN
+
         if scope != SCOPE_BASE and scope != SCOPE_SUBTREE:
             raise NotImplementedError(str(scope))
         store = Store.instance()

nova/auth/ldapdriver.py

@@ -101,6 +101,41 @@ def sanitize(fn):
     return _wrapped
 
 
+class LDAPWrapper(object):
+    def __init__(self, ldap, url, user, password):
+        self.ldap = ldap
+        self.url = url
+        self.user = user
+        self.password = password
+        self.conn = None
+
+    def __wrap_reconnect(f):
+        def inner(self, *args, **kwargs):
+            if self.conn is None:
+                self.connect()
+                return f(self.conn)(*args, **kwargs)
+            else:
+                try:
+                    return f(self.conn)(*args, **kwargs)
+                except self.ldap.SERVER_DOWN:
+                    self.connect()
+                    return f(self.conn)(*args, **kwargs)
+        return inner
+
+    def connect(self):
+        try:
+            self.conn = self.ldap.initialize(self.url)
+            self.conn.simple_bind_s(self.user, self.password)
+        except self.ldap.SERVER_DOWN:
+            self.conn = None
+            raise
+
+    search_s = __wrap_reconnect(lambda conn: conn.search_s)
+    add_s = __wrap_reconnect(lambda conn: conn.add_s)
+    delete_s = __wrap_reconnect(lambda conn: conn.delete_s)
+    modify_s = __wrap_reconnect(lambda conn: conn.modify_s)
+
+
 class LdapDriver(object):
     """Ldap Auth driver
 
@@ -124,8 +159,8 @@ class LdapDriver(object):
             LdapDriver.project_objectclass = 'novaProject'
         self.__cache = None
         if LdapDriver.conn is None:
-            LdapDriver.conn = self.ldap.initialize(FLAGS.ldap_url)
-            LdapDriver.conn.simple_bind_s(FLAGS.ldap_user_dn,
+            LdapDriver.conn = LDAPWrapper(self.ldap, FLAGS.ldap_url,
+                                          FLAGS.ldap_user_dn,
                                           FLAGS.ldap_password)
         if LdapDriver.mc is None:
             LdapDriver.mc = memcache.Client(FLAGS.memcached_servers, debug=0)

nova/tests/test_auth.py

@@ -25,6 +25,7 @@ from nova import log as logging
 from nova import test
 from nova.auth import manager
 from nova.api.ec2 import cloud
+from nova.auth import fakeldap
 
 FLAGS = flags.FLAGS
 LOG = logging.getLogger('nova.tests.auth_unittest')
@@ -369,6 +370,15 @@ class _AuthManagerBaseTestCase(test.TestCase):
 class AuthManagerLdapTestCase(_AuthManagerBaseTestCase):
     auth_driver = 'nova.auth.ldapdriver.FakeLdapDriver'
 
+    def test_reconnect_on_server_failure(self):
+        self.manager.get_users()
+        fakeldap.server_fail = True
+        try:
+            self.assertRaises(fakeldap.SERVER_DOWN, self.manager.get_users)
+        finally:
+            fakeldap.server_fail = False
+        self.manager.get_users()
+
 
 class AuthManagerDbTestCase(_AuthManagerBaseTestCase):
     auth_driver = 'nova.auth.dbdriver.DbDriver'