Add Blazar custom constraint plugin

This adds a reservation constraint for verifying a blazar
reservation id.

Change-Id: I27267e148c71288b4c7701fe704425b738e3e0b3
Story: 2005654
Task: 30942

heat/engine/clients/os/blazar.py

@@ -14,7 +14,9 @@
 from blazarclient import client as blazar_client
 from blazarclient import exception as client_exception
 
+from heat.common import exception
 from heat.engine.clients import client_plugin
+from heat.engine import constraints
 
 CLIENT_NAME = 'blazar'
 
@@ -56,3 +58,16 @@ class BlazarClientPlugin(client_plugin.ClientPlugin):
 
     def get_host(self, id):
         return self.client().host.get(id)
+
+
+class BlazarBaseConstraint(constraints.BaseCustomConstraint):
+
+    resource_client_name = CLIENT_NAME
+
+
+class ReservationConstraint(BlazarBaseConstraint):
+    expected_exceptions = (
+        exception.EntityNotFound,
+        client_exception.BlazarClientException,)
+
+    resource_getter_name = 'get_lease'

setup.cfg

@@ -108,6 +108,7 @@ heat.constraints =
     # service constraints
     barbican.container = heat.engine.clients.os.barbican:ContainerConstraint
     barbican.secret = heat.engine.clients.os.barbican:SecretConstraint
+    blazar.reservation = heat.engine.clients.os.blazar:ReservationConstraint
     cinder.backup = heat.engine.clients.os.cinder:VolumeBackupConstraint
     cinder.qos_specs = heat.engine.clients.os.cinder:QoSSpecsConstraint
     cinder.snapshot = heat.engine.clients.os.cinder:VolumeSnapshotConstraint