Mark Dependency status as Unknown when the dependency object's generation is not equal

pkg/reconciler/trigger/trigger.go

@@ -260,15 +260,16 @@ func (r *Reconciler) propagateDependencyReadiness(dependencyObjRef corev1.Object
 		return fmt.Errorf("getting the dependency: %v", err)
 	}
 	dependency := dependencyObj.(*duckv1alpha1.KResource)
-	// Temporarily comment it until we figure out whether we update Status.ObservedGeneration when KResource changes
-	// From manual testing, it looks like we never update  Status.ObservedGeneration
-	//if dependency.GetGeneration() != dependency.Status.ObservedGeneration {
-	//	logging.FromContext(ctx).Error("The ObjectMeta Generation of dependency is not equal to the observedGeneration of status",
-	//		zap.Any("ObjectMeta Generation of dependency", dependency.GetGeneration()),
-	//		zap.Any("ObservedGeneration of status", dependency.Status.ObservedGeneration))
-	//	t.Status.MarkDependencyUnknown("GenerationNotEqual", "The ObjectMeta Generation of dependency %d is not equal to the ObservedGeneration of status %d", dependency.GetGeneration(), dependency.Status.ObservedGeneration)
-	//	return nil
-	//}
+
+	// The dependency hasn't yet reconciled our latest changes to
+	// its desired state, so its conditions are outdated.
+	if dependency.GetGeneration() != dependency.Status.ObservedGeneration {
+		logging.FromContext(ctx).Info("The ObjectMeta Generation of dependency is not equal to the observedGeneration of status",
+			zap.Any("objectMetaGeneration", dependency.GetGeneration()),
+			zap.Any("statusObservedGeneration", dependency.Status.ObservedGeneration))
+		t.Status.MarkDependencyUnknown("GenerationNotEqual", "The dependency's metadata.generation, %q, is not equal to its status.observedGeneration, %q.", dependency.GetGeneration(), dependency.Status.ObservedGeneration)
+		return nil
+	}
 	t.Status.PropagateDependencyStatus(dependency)
 	return nil
 }

pkg/reconciler/trigger/trigger_test.go

@@ -79,6 +79,9 @@ const (
 	testSchedule            = "*/2 * * * *"
 	testData                = "data"
 	sinkName                = "testsink"
+
+	currentGeneration  = 1
+	outdatedGeneration = 0
 )
 
 var (
@@ -568,6 +571,37 @@ func TestAllCases(t *testing.T) {
 				),
 			}},
 		}, {
+			Name: "Dependency generation not equal",
+			Key:  triggerKey,
+			Objects: []runtime.Object{
+				makeReadyBroker(),
+				makeBrokerFilterService(),
+				makeReadySubscription(),
+				makeGenerationNotEqualCronJobSource(),
+				reconciletesting.NewTrigger(triggerName, testNS, brokerName,
+					reconciletesting.WithTriggerUID(triggerUID),
+					reconciletesting.WithTriggerSubscriberURI(subscriberURI),
+					reconciletesting.WithInitTriggerConditions,
+					reconciletesting.WithDependencyAnnotation(dependencyAnnotation),
+				),
+			},
+			WantErr: false,
+			WantEvents: []string{
+				Eventf(corev1.EventTypeNormal, "TriggerReconciled", "Trigger reconciled")},
+			WantStatusUpdates: []clientgotesting.UpdateActionImpl{{
+				Object: reconciletesting.NewTrigger(triggerName, testNS, brokerName,
+					reconciletesting.WithTriggerUID(triggerUID),
+					reconciletesting.WithTriggerSubscriberURI(subscriberURI),
+					// The first reconciliation will initialize the status conditions.
+					reconciletesting.WithInitTriggerConditions,
+					reconciletesting.WithDependencyAnnotation(dependencyAnnotation),
+					reconciletesting.WithTriggerBrokerReady(),
+					reconciletesting.WithTriggerSubscribed(),
+					reconciletesting.WithTriggerStatusSubscriberURI(subscriberURI),
+					reconciletesting.WithTriggerDependencyUnknown("GenerationNotEqual", fmt.Sprintf("The dependency's metadata.generation, %q, is not equal to its status.observedGeneration, %q.", currentGeneration, outdatedGeneration))),
+			}},
+		},
+		{
 			Name: "Dependency ready",
 			Key:  triggerKey,
 			Objects: []runtime.Object{
@@ -761,6 +795,13 @@ func makeNotReadyCronJobSource() *sourcesv1alpha1.CronJobSource {
 	return NewCronJobSource(cronJobSourceName, testNS, WithCronJobApiVersion(cronJobSourceAPIVersion), WithCronJobSourceSinkNotFound)
 }
 
+func makeGenerationNotEqualCronJobSource() *sourcesv1alpha1.CronJobSource {
+	c := makeNotReadyCronJobSource()
+	c.Generation = currentGeneration
+	c.Status.ObservedGeneration = outdatedGeneration
+	return c
+}
+
 func makeReadyCronJobSource() *sourcesv1alpha1.CronJobSource {
 	return NewCronJobSource(cronJobSourceName, testNS,
 		WithCronJobApiVersion(cronJobSourceAPIVersion),