Provide a signal URL attribute for alarms

This patch adds a new attribute to scaling policies allowing it to be
called by the ceilometer service user using trusts on alarming.

Implements: blueprint trust-alarm-urls
Change-Id: Ic039d9aaf3804ab09e3d546d3ae55a18b528d585

heat/engine/resources/openstack/heat/scaling_policy.py

@@ -22,6 +22,7 @@ from heat.engine import constraints
 from heat.engine import properties
 from heat.engine import resource
 from heat.engine.resources import signal_responder
+from heat.engine import support
 from heat.scaling import cooldown
 
 LOG = logging.getLogger(__name__)
@@ -47,9 +48,9 @@ class AutoScalingPolicy(signal_responder.SignalResponder,
         'exact_capacity', 'change_in_capacity', 'percent_change_in_capacity')
 
     ATTRIBUTES = (
-        ALARM_URL,
+        ALARM_URL, SIGNAL_URL
     ) = (
-        'alarm_url',
+        'alarm_url', 'signal_url'
     )
 
     properties_schema = {
@@ -101,6 +102,11 @@ class AutoScalingPolicy(signal_responder.SignalResponder,
         ALARM_URL: attributes.Schema(
             _("A signed url to handle the alarm.")
         ),
+        SIGNAL_URL: attributes.Schema(
+            _("A url to handle the alarm using native API."),
+            support_status=support.SupportStatus(version='2015.2'),
+            type=attributes.Schema.STRING
+        ),
     }
 
     def validate(self):
@@ -182,8 +188,10 @@ class AutoScalingPolicy(signal_responder.SignalResponder,
                                   self.properties[self.SCALING_ADJUSTMENT]))
 
     def _resolve_attribute(self, name):
-        if name == self.ALARM_URL and self.resource_id is not None:
+        if name == self.ALARM_URL:
             return six.text_type(self._get_signed_url())
+        elif name == self.SIGNAL_URL:
+            return six.text_type(self._get_signal_url())
 
     def FnGetRefId(self):
         return resource.Resource.FnGetRefId(self)

heat/engine/resources/signal_responder.py

@@ -104,3 +104,18 @@ class SignalResponder(stack_user.StackUser):
 
         self.data_set('ec2_signed_url', url)
         return url
+
+    def _get_signal_url(self):
+        stored = self.data().get('signal_url')
+        if stored is not None:
+            return stored
+
+        url = self.client_plugin('heat').get_heat_url()
+        host_url = urlparse.urlparse(url)
+        path = self.identifier().url_path()
+
+        url = urlparse.urlunsplit(
+            (host_url.scheme, host_url.netloc, 'v1/%s/signal' % path, '', ''))
+
+        self.data_set('signal_url', url)
+        return url

heat/tests/autoscaling/test_heat_scaling_policy.py

@@ -237,3 +237,16 @@ class ScalingPolicyAttrTest(common.HeatTestCase):
         self.assertEqual('SignatureVersion', args[3].split('=')[0])
         self.assertEqual('Signature', args[4].split('=')[0])
         self.m.VerifyAll()
+
+    def test_signal_attribute(self):
+        self.m.StubOutWithMock(self.stack.clients.client_plugin('heat'),
+                               'get_heat_url')
+        self.stack.clients.client_plugin('heat').get_heat_url().AndReturn(
+            'http://server.test:8000/v1')
+        self.m.ReplayAll()
+        self.assertEqual(
+            'http://server.test:8000/v1/test_tenant_id/stacks/'
+            '%s/%s/resources/my-policy/signal' % (
+                self.stack.name, self.stack.id),
+            self.policy.FnGetAtt('signal_url'))
+        self.m.VerifyAll()