To delete the keypair preparing for update replacement

If the keypair resource is in *_FAILED, to update it will
enter UpdateReplacement, but maybe the keypair exists still
in nova, then we can't recreate the new one, so try to delete
the old one preparing for update replacement.

Change-Id: Ic5a4e1eb4625dcefe5accc484b2c8db7fbb2940d
Closes-Bug: #1597602

heat/engine/resources/openstack/nova/keypair.py

@@ -135,6 +135,13 @@ class KeyPair(resource.Resource):
     def get_reference_id(self):
         return self.resource_id
 
+    def prepare_for_replace(self):
+        if self.resource_id is None:
+            return
+
+        with self.client_plugin().ignore_not_found:
+            self.client().keypairs.delete(self.resource_id)
+
 
 def resource_mapping():
     return {'OS::Nova::KeyPair': KeyPair}

heat/tests/openstack/nova/test_keypair.py

@@ -145,6 +145,18 @@ class NovaKeyPairTest(common.HeatTestCase):
         self.assertIn("boom", six.text_type(exc))
         self.assertEqual((res.CHECK, res.FAILED), res.state)
 
+    def test_update_replace(self):
+        res = self._get_test_resource(self.kp_template)
+        res.state_set(res.CHECK, res.FAILED, 'for test')
+        res.resource_id = 'my_key'
+        # to delete the keypair preparing for replace
+        self.fake_keypairs.delete('my_key')
+        self.m.ReplayAll()
+        updater = scheduler.TaskRunner(res.update, res.t)
+        self.assertRaises(exception.UpdateReplace, updater)
+
+        self.m.ReplayAll()
+
     def test_delete_key_not_found(self):
         """Test delete non-existent key."""
         test_res = self._get_test_resource(self.kp_template)