diff --git a/charms_openstack/adapters.py b/charms_openstack/adapters.py
index 082a680..88ea2c4 100644
--- a/charms_openstack/adapters.py
+++ b/charms_openstack/adapters.py
@@ -84,6 +84,31 @@ def config_property(f):
     _custom_config_properties[property_name] = f
     return f
 
+
+@config_property
+def config_flags(cls):
+    """Decorator to add a custom configuration property with
+    config-flags to add extra options.
+
+    :param cls: Configuration Adapter class
+    :type cls: charms_openstack.adapters.DefaultConfigurationAdapter
+    """
+    cf_config = {}
+    config = hookenv.config
+    if config and 'config-flags' in config:
+        # match 0 or multiple time any pair of character a=b divide by a coma
+        # zero or one spaces are allows between tokens
+        parsing_regex = r"^(?:\s{0,1}[^=]\s{0,1}=\s{0,1}[^,]\s{0,1}(?:,|$))*$"
+        if re.match(parsing_regex, config['config-flags']):
+            cf_config = dict(map(lambda x: [s.strip() for s in x.split('=')],
+                                 config['config-flags']
+                                 .split(',')))
+        else:
+            raise RuntimeError("config-flags string error: {}".format(config))
+
+    return cf_config
+
+
 ##
 
 
diff --git a/unit_tests/test_charms_openstack_adapters.py b/unit_tests/test_charms_openstack_adapters.py
index 589f0f1..2d468cf 100644
--- a/unit_tests/test_charms_openstack_adapters.py
+++ b/unit_tests/test_charms_openstack_adapters.py
@@ -51,6 +51,66 @@ class TestCustomProperties(unittest.TestCase):
             self.assertTrue(adapters._custom_config_properties['test_func'],
                             test_func)
 
+    def test_user_config_flags(self):
+        cfg = {
+            'config-flags': "a = b,c=d, e= f",
+        }
+        cls_mock = mock.MagicMock()
+        with mock.patch.object(adapters.hookenv,
+                               'config',
+                               new=cfg):
+
+            conf = adapters.config_flags(cls_mock)
+            self.assertEqual(conf['a'], 'b')
+            self.assertEqual(conf['c'], 'd')
+            self.assertEqual(conf['e'], 'f')
+
+    def test_user_config_flags_parsing_error_1(self):
+        cfg = {
+            'config-flags': "a = b, c = d e= f",
+        }
+        cls_mock = mock.MagicMock()
+        with mock.patch.object(adapters.hookenv,
+                               'config',
+                               new=cfg):
+
+            with self.assertRaises(RuntimeError):
+                adapters.config_flags(cls_mock)
+
+    def test_user_config_flags_parsing_error_2(self):
+        cfg = {
+            'config-flags': "a = b, c  d, e= f",
+        }
+        cls_mock = mock.MagicMock()
+        with mock.patch.object(adapters.hookenv,
+                               'config',
+                               new=cfg):
+
+            with self.assertRaises(RuntimeError):
+                adapters.config_flags(cls_mock)
+
+    def test_user_config_flags_missing(self):
+        cfg = {
+            'other-flags': 1
+        }
+        cls_mock = mock.MagicMock()
+        with mock.patch.object(adapters.hookenv,
+                               'config',
+                               new=cfg):
+
+            conf = adapters.config_flags(cls_mock)
+            self.assertEqual(conf, {})
+
+    def test_user_config_none(self):
+        cfg = None
+        cls_mock = mock.MagicMock()
+        with mock.patch.object(adapters.hookenv,
+                               'config',
+                               new=cfg):
+
+            conf = adapters.config_flags(cls_mock)
+            self.assertEqual(conf, {})
+
 
 class MyRelation(object):