On delete, also attempt to update controller state, in case we

missed a previous update.  Add a test to validate that this works

pkg/controller/replication_controller.go

@@ -148,7 +148,21 @@ func (rm *ReplicationManager) handleWatchResponse(response *etcd.Response) (*api
 		} else {
 			return nil, fmt.Errorf("response node is null %#v", response)
 		}
+	} else if response.Action == "delete" {
+		// Ensure that the final state of a replication controller is applied before it is deleted.
+		// Otherwise, a replication controller could be modified and then deleted (for example, from 3 to 0
+		// replicas), and it would be non-deterministic which of its pods continued to exist.
+		if response.PrevNode != nil {
+			var controllerSpec api.ReplicationController
+			if err := json.Unmarshal([]byte(response.PrevNode.Value), &controllerSpec); err != nil {
+				return nil, err
 			}
+			return &controllerSpec, nil
+		} else {
+			return nil, fmt.Errorf("previous node is null %#v", response)
+		}
+	}
+
 	return nil, nil
 }
 

pkg/controller/replication_controller_test.go

@@ -231,7 +231,7 @@ func TestHandleWatchResponseNotSet(t *testing.T) {
 	manager := MakeReplicationManager(nil, &client)
 	manager.podControl = &fakePodControl
 	_, err := manager.handleWatchResponse(&etcd.Response{
-		Action: "delete",
+		Action: "update",
 	})
 	expectNoError(t, err)
 }
@@ -319,6 +319,40 @@ func TestHandleWatchResponse(t *testing.T) {
 	}
 }
 
+func TestHandleWatchResponseDelete(t *testing.T) {
+	body, _ := json.Marshal(makePodList(2))
+	fakeHandler := util.FakeHandler{
+		StatusCode:   200,
+		ResponseBody: string(body),
+	}
+	testServer := httptest.NewTLSServer(&fakeHandler)
+	client := client.Client{
+		Host: testServer.URL,
+	}
+
+	fakePodControl := FakePodControl{}
+
+	manager := MakeReplicationManager(nil, &client)
+	manager.podControl = &fakePodControl
+
+	controller := makeReplicationController(2)
+
+	data, err := json.Marshal(controller)
+	expectNoError(t, err)
+	controllerOut, err := manager.handleWatchResponse(&etcd.Response{
+		Action: "delete",
+		PrevNode: &etcd.Node{
+			Value: string(data),
+		},
+	})
+	if err != nil {
+		t.Errorf("Unexpected error: %#v", err)
+	}
+	if !reflect.DeepEqual(controller, *controllerOut) {
+		t.Errorf("Unexpected mismatch.  Expected %#v, Saw: %#v", controller, controllerOut)
+	}
+}
+
 func TestSyncronize(t *testing.T) {
 	controllerSpec1 := api.ReplicationController{
 		DesiredState: api.ReplicationControllerState{