Support loading constraints as stevedore extensions

This still maintains support for the existing mechanism
but moves the in tree constraints to using stevedore.

part of blueprint stevedore-plugins
Change-Id: I86907e6518281083a508f840269d79dfa3875e9a

heat/engine/resources/__init__.py

@@ -11,6 +11,8 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
+from stevedore import extension
+
 from heat.engine import environment
 from heat.engine import plugin_manager
 
@@ -25,6 +27,14 @@ def _register_constraints(env, type_pairs):
         env.register_constraint(constraint_name, constraint)
 
 
+def _get_mapping(namespace):
+    mgr = extension.ExtensionManager(
+        namespace=namespace,
+        invoke_on_load=False,
+        verify_requirements=True)
+    return [[name, mgr[name].plugin] for name in mgr.names()]
+
+
 _environment = None
 
 
@@ -50,8 +60,9 @@ def _load_global_environment(env):
 
 
 def _load_global_resources(env):
-    manager = plugin_manager.PluginManager(__name__)
+    _register_constraints(env, _get_mapping('heat.constraints'))
 
+    manager = plugin_manager.PluginManager(__name__)
     # Sometimes resources should not be available for registration in Heat due
     # to unsatisfied dependencies. We look first for the function
     # 'available_resource_mapping', which should return the filtered resources.
@@ -61,4 +72,5 @@ def _load_global_resources(env):
     constraint_mapping = plugin_manager.PluginMapping('constraint')
 
     _register_resources(env, resource_mapping.load_all(manager))
+
     _register_constraints(env, constraint_mapping.load_all(manager))

heat/engine/resources/image.py

@@ -23,7 +23,3 @@ class ImageConstraint(constraints.BaseCustomConstraint):
     def validate_with_client(self, client, value):
         glance_client = client.glance()
         glance_utils.get_image_id(glance_client, value)
-
-
-def constraint_mapping():
-    return {'glance.image': ImageConstraint}

heat/engine/resources/iso_8601.py

@@ -23,7 +23,3 @@ class ISO8601Constraint(object):
             return False
         else:
             return True
-
-
-def constraint_mapping():
-    return {'iso_8601': ISO8601Constraint}

heat/engine/resources/neutron/net.py

@@ -194,12 +194,6 @@ class NetworkConstraint(constraints.BaseCustomConstraint):
             neutron_client, 'network', value)
 
 
-def constraint_mapping():
-    if clients.neutronclient is None:
-        return {}
-    return {'neutron.network': NetworkConstraint}
-
-
 def resource_mapping():
     if clients.neutronclient is None:
         return {}

heat/engine/resources/nova_keypair.py

@@ -142,9 +142,5 @@ class KeypairConstraint(constraints.BaseCustomConstraint):
         nova_utils.get_keypair(nova_client, value)
 
 
-def constraint_mapping():
-    return {'nova.keypair': KeypairConstraint}
-
-
 def resource_mapping():
     return {'OS::Nova::KeyPair': KeyPair}

heat/engine/resources/server.py

@@ -1053,10 +1053,6 @@ class FlavorConstraint(constraints.BaseCustomConstraint):
         nova_utils.get_flavor_id(nova_client, value)
 
 
-def constraint_mapping():
-    return {'nova.flavor': FlavorConstraint}
-
-
 def resource_mapping():
     return {
         'OS::Nova::Server': Server,

heat/tests/test_environment.py

@@ -153,6 +153,14 @@ def constraint_mapping():
                                   resources._load_global_environment, env)
         self.assertEqual("oops", str(error))
 
+    def test_constraints_registry_stevedore(self):
+        env = environment.Environment({})
+        resources._load_global_environment(env)
+
+        self.assertEqual("FlavorConstraint",
+                         env.get_constraint("nova.flavor").__name__)
+        self.assertIs(None, env.get_constraint("no_constraint"))
+
 
 class EnvironmentDuplicateTest(common.HeatTestCase):
 

requirements.txt

@@ -29,4 +29,5 @@ Routes>=1.12.3
 six>=1.6.0
 SQLAlchemy>=0.7.8,<=0.9.99
 sqlalchemy-migrate>=0.9.1
+stevedore>=0.14
 WebOb>=1.2.3

setup.cfg

@@ -37,6 +37,14 @@ oslo.config.opts =
     heat.common.config = heat.common.config:list_opts
     heat.common.wsgi = heat.common.wsgi:list_opts
 
+heat.constraints =
+    nova.flavor = heat.engine.resources.server:FlavorConstraint
+    neutron.network = heat.engine.resources.neutron.net:NetworkConstraint
+    glance.image = heat.engine.resources.image:ImageConstraint
+    iso_8601 = heat.engine.resources.iso_8601:ISO8601Constraint
+    nova.keypair = heat.engine.resources.nova_keypair:KeypairConstraint
+
+
 [global]
 setup-hooks =
     pbr.hooks.setup_hook