Add a method for obtaining the maximum password length

The patch adds `get_maximum_password_length` to osutils. The Windows
specific value which was used in setuserpassword and createuser plugins
is moved in the Windows implementation of get_maximum_password_length.

Change-Id: I08f999c750ac7e2858493072d41bb8f4927521ca

cloudbaseinit/osutils/base.py

@@ -106,3 +106,7 @@ class BaseOSUtils(object):
 
     def firewall_remove_rule(self, name, port, protocol, allow=True):
         raise NotImplementedError()
+
+    def get_maximum_password_length(self):
+        """Obtain the maximum password length tailored for each OS."""
+        raise NotImplementedError()

cloudbaseinit/osutils/windows.py

@@ -991,3 +991,7 @@ class WindowsUtils(base.BaseOSUtils):
         process_path = os.path.join(base_dir, args[0])
         return self.execute_process([process_path] + args[1:],
                                     decode_output=decode_output, shell=shell)
+
+    def get_maximum_password_length(self):
+        # TODO(cpopa): Limit to 14 chars for compatibility with NT?
+        return 14

cloudbaseinit/plugins/common/createuser.py

@@ -35,10 +35,12 @@ LOG = logging.getLogger(__name__)
 
 class CreateUserPlugin(base.BasePlugin):
 
-    def _get_password(self, osutils):
+    @staticmethod
+    def _get_password(osutils):
         # Generate a temporary random password to be replaced
         # by SetUserPasswordPlugin (starting from Grizzly)
-        return osutils.generate_random_password(14)
+        maximum_length = osutils.get_maximum_password_length()
+        return osutils.generate_random_password(maximum_length)
 
     def execute(self, service, shared_data):
         user_name = CONF.username

cloudbaseinit/plugins/common/setuserpassword.py

@@ -63,8 +63,8 @@ class SetUserPasswordPlugin(base.BasePlugin):
             if not password:
                 LOG.debug('Generating a random user password')
                 # Generate a random password
-                # Limit to 14 chars for compatibility with NT
-                password = osutils.generate_random_password(14)
+                maximum_length = osutils.get_maximum_password_length()
+                password = osutils.generate_random_password(maximum_length)
 
         return password
 

cloudbaseinit/tests/osutils/test_windows.py

@@ -1357,3 +1357,6 @@ class TestWindowsUtils(unittest.TestCase):
             decode_output=False,
             shell=True)
         self.assertEqual(mock.sentinel.execute_process, result)
+
+    def test_get_password_maximum_length(self):
+        self.assertEqual(14, self._winutils.get_maximum_password_length())

cloudbaseinit/tests/plugins/common/test_createuser.py

@@ -36,7 +36,9 @@ class CreateUserPluginTests(unittest.TestCase):
         mock_osutils = mock.MagicMock()
         mock_osutils.generate_random_password.return_value = 'fake password'
         response = self._create_user._get_password(mock_osutils)
-        mock_osutils.generate_random_password.assert_called_once_with(14)
+        mock_osutils.get_maximum_password_length.assert_called_once_with()
+        length = mock_osutils.get_maximum_password_length()
+        mock_osutils.generate_random_password.assert_called_once_with(length)
         self.assertEqual('fake password', response)
 
     @testutils.ConfPatcher('groups', ['Admins'])

cloudbaseinit/tests/plugins/common/test_setuserpassword.py

@@ -97,8 +97,9 @@ class SetUserPasswordPluginTests(unittest.TestCase):
             self.assertFalse(mock_osutils.generate_random_password.called)
             expected_password = mock.sentinel.create_user_password
         else:
-            mock_osutils.generate_random_password.assert_called_once_with(14)
-
+            mock_osutils.get_maximum_password_length.assert_called_once_with()
+            mock_osutils.generate_random_password.assert_called_once_with(
+                mock_osutils.get_maximum_password_length())
         self.assertEqual(expected_password, response)
 
     def test_get_password_inject_true(self):