Fix to handle hash collisions correctly for DaemonSets

pkg/controller/daemon/update.go

@@ -330,16 +330,16 @@ func (dsc *DaemonSetsController) snapshot(ds *apps.DaemonSet, revision int64) (*
 	}
 
 	history, err = dsc.kubeClient.AppsV1().ControllerRevisions(ds.Namespace).Create(history)
-	if errors.IsAlreadyExists(err) {
+	if outerErr := err; errors.IsAlreadyExists(outerErr) {
 		// TODO: Is it okay to get from historyLister?
 		existedHistory, getErr := dsc.kubeClient.AppsV1().ControllerRevisions(ds.Namespace).Get(name, metav1.GetOptions{})
 		if getErr != nil {
 			return nil, getErr
 		}
 		// Check if we already created it
-		done, err := Match(ds, existedHistory)
-		if err != nil {
-			return nil, err
+		done, matchErr := Match(ds, existedHistory)
+		if matchErr != nil {
+			return nil, matchErr
 		}
 		if done {
 			return existedHistory, nil
@@ -360,7 +360,7 @@ func (dsc *DaemonSetsController) snapshot(ds *apps.DaemonSet, revision int64) (*
 			return nil, updateErr
 		}
 		glog.V(2).Infof("Found a hash collision for DaemonSet %q - bumping collisionCount to %d to resolve it", ds.Name, *currDS.Status.CollisionCount)
-		return nil, err
+		return nil, outerErr
 	}
 	return history, err
 }

test/integration/daemonset/BUILD

@@ -16,12 +16,14 @@ go_test(
     deps = [
         "//pkg/api/legacyscheme:go_default_library",
         "//pkg/api/v1/pod:go_default_library",
+        "//pkg/controller:go_default_library",
         "//pkg/controller/daemon:go_default_library",
         "//pkg/features:go_default_library",
         "//pkg/scheduler:go_default_library",
         "//pkg/scheduler/algorithm:go_default_library",
         "//pkg/scheduler/algorithmprovider:go_default_library",
         "//pkg/scheduler/factory:go_default_library",
+        "//pkg/util/labels:go_default_library",
         "//pkg/util/metrics:go_default_library",
         "//staging/src/k8s.io/api/apps/v1:go_default_library",
         "//staging/src/k8s.io/api/core/v1:go_default_library",

test/integration/daemonset/daemonset_test.go

@@ -41,13 +41,15 @@ import (
 	"k8s.io/client-go/tools/record"
 	"k8s.io/kubernetes/pkg/api/legacyscheme"
 	podutil "k8s.io/kubernetes/pkg/api/v1/pod"
+	"k8s.io/kubernetes/pkg/controller"
 	"k8s.io/kubernetes/pkg/controller/daemon"
 	"k8s.io/kubernetes/pkg/features"
 	"k8s.io/kubernetes/pkg/scheduler"
 	"k8s.io/kubernetes/pkg/scheduler/algorithm"
 	"k8s.io/kubernetes/pkg/scheduler/algorithmprovider"
 	_ "k8s.io/kubernetes/pkg/scheduler/algorithmprovider"
 	"k8s.io/kubernetes/pkg/scheduler/factory"
+	labelsutil "k8s.io/kubernetes/pkg/util/labels"
 	"k8s.io/kubernetes/pkg/util/metrics"
 	"k8s.io/kubernetes/test/integration/framework"
 )
@@ -372,6 +374,52 @@ func waitForPodsCreated(podInformer cache.SharedIndexInformer, num int) error {
 	})
 }
 
+func waitForDaemonSetAndControllerRevisionCreated(c clientset.Interface, name string, namespace string) error {
+	return wait.PollImmediate(100*time.Millisecond, 10*time.Second, func() (bool, error) {
+		ds, err := c.AppsV1().DaemonSets(namespace).Get(name, metav1.GetOptions{})
+		if err != nil {
+			return false, err
+		}
+		if ds == nil {
+			return false, nil
+		}
+
+		revs, err := c.AppsV1().ControllerRevisions(namespace).List(metav1.ListOptions{})
+		if err != nil {
+			return false, err
+		}
+		if revs.Size() == 0 {
+			return false, nil
+		}
+
+		for _, rev := range revs.Items {
+			for _, oref := range rev.OwnerReferences {
+				if oref.Kind == "DaemonSet" && oref.UID == ds.UID {
+					return true, nil
+				}
+			}
+		}
+		return false, nil
+	})
+}
+
+func hashAndNameForDaemonSet(ds *apps.DaemonSet) (string, string) {
+	hash := fmt.Sprint(controller.ComputeHash(&ds.Spec.Template, ds.Status.CollisionCount))
+	name := ds.Name + "-" + hash
+	return hash, name
+}
+
+func validateDaemonSetCollisionCount(dsClient appstyped.DaemonSetInterface, dsName string, expCount int32, t *testing.T) {
+	ds, err := dsClient.Get(dsName, metav1.GetOptions{})
+	if err != nil {
+		t.Fatalf("Failed to look up DaemonSet: %v", err)
+	}
+	collisionCount := ds.Status.CollisionCount
+	if *collisionCount != expCount {
+		t.Fatalf("Expected collisionCount to be %d, but found %d", expCount, *collisionCount)
+	}
+}
+
 func validateDaemonSetStatus(
 	dsClient appstyped.DaemonSetInterface,
 	dsName string,
@@ -740,3 +788,112 @@ func TestInsufficientCapacityNodeWhenScheduleDaemonSetPodsEnabled(t *testing.T)
 		validateDaemonSetStatus(dsClient, ds.Name, 1, t)
 	})
 }
+
+// TestLaunchWithHashCollision tests that a DaemonSet can be updated even if there is a
+// hash collision with an existing ControllerRevision
+func TestLaunchWithHashCollision(t *testing.T) {
+	server, closeFn, dc, informers, clientset := setup(t)
+	defer closeFn()
+	ns := framework.CreateTestingNamespace("one-node-daemonset-test", server, t)
+	defer framework.DeleteTestingNamespace(ns, server, t)
+
+	dsClient := clientset.AppsV1().DaemonSets(ns.Name)
+	podInformer := informers.Core().V1().Pods().Informer()
+	nodeClient := clientset.CoreV1().Nodes()
+
+	stopCh := make(chan struct{})
+	defer close(stopCh)
+
+	informers.Start(stopCh)
+	go dc.Run(1, stopCh)
+
+	setupScheduler(t, clientset, informers, stopCh)
+
+	// Create single node
+	_, err := nodeClient.Create(newNode("single-node", nil))
+	if err != nil {
+		t.Fatalf("Failed to create node: %v", err)
+	}
+
+	// Create new DaemonSet with RollingUpdate strategy
+	orgDs := newDaemonSet("foo", ns.Name)
+	oneIntString := intstr.FromInt(1)
+	orgDs.Spec.UpdateStrategy = apps.DaemonSetUpdateStrategy{
+		Type: apps.RollingUpdateDaemonSetStrategyType,
+		RollingUpdate: &apps.RollingUpdateDaemonSet{
+			MaxUnavailable: &oneIntString,
+		},
+	}
+	ds, err := dsClient.Create(orgDs)
+	if err != nil {
+		t.Fatalf("Failed to create DaemonSet: %v", err)
+	}
+
+	// Wait for the DaemonSet to be created before proceeding
+	err = waitForDaemonSetAndControllerRevisionCreated(clientset, ds.Name, ds.Namespace)
+	if err != nil {
+		t.Fatalf("Failed to create DeamonSet: %v", err)
+	}
+
+	ds, err = dsClient.Get(ds.Name, metav1.GetOptions{})
+	if err != nil {
+		t.Fatalf("Failed to get DaemonSet: %v", err)
+	}
+	var orgCollisionCount int32
+	if ds.Status.CollisionCount != nil {
+		orgCollisionCount = *ds.Status.CollisionCount
+	}
+
+	// Look up the ControllerRevision for the DaemonSet
+	_, name := hashAndNameForDaemonSet(ds)
+	revision, err := clientset.AppsV1().ControllerRevisions(ds.Namespace).Get(name, metav1.GetOptions{})
+	if err != nil || revision == nil {
+		t.Fatalf("Failed to look up ControllerRevision: %v", err)
+	}
+
+	// Create a "fake" ControllerRevision that we know will create a hash collision when we make
+	// the next update
+	one := int64(1)
+	ds.Spec.Template.Spec.TerminationGracePeriodSeconds = &one
+
+	newHash, newName := hashAndNameForDaemonSet(ds)
+	newRevision := &apps.ControllerRevision{
+		ObjectMeta: metav1.ObjectMeta{
+			Name:            newName,
+			Namespace:       ds.Namespace,
+			Labels:          labelsutil.CloneAndAddLabel(ds.Spec.Template.Labels, apps.DefaultDaemonSetUniqueLabelKey, newHash),
+			Annotations:     ds.Annotations,
+			OwnerReferences: []metav1.OwnerReference{*metav1.NewControllerRef(ds, apps.SchemeGroupVersion.WithKind("DaemonSet"))},
+		},
+		Data:     revision.Data,
+		Revision: revision.Revision + 1,
+	}
+	_, err = clientset.AppsV1().ControllerRevisions(ds.Namespace).Create(newRevision)
+	if err != nil {
+		t.Fatalf("Failed to create ControllerRevision: %v", err)
+	}
+
+	// Make an update of the DaemonSet which we know will create a hash collision when
+	// the next ControllerRevision is created.
+	_, err = dsClient.Update(ds)
+	if err != nil {
+		t.Fatalf("Failed to update DaemonSet: %v", err)
+	}
+
+	// Wait for any pod with the latest Spec to exist
+	err = wait.PollImmediate(100*time.Millisecond, 10*time.Second, func() (bool, error) {
+		objects := podInformer.GetIndexer().List()
+		for _, object := range objects {
+			pod := object.(*v1.Pod)
+			if *pod.Spec.TerminationGracePeriodSeconds == *ds.Spec.Template.Spec.TerminationGracePeriodSeconds {
+				return true, nil
+			}
+		}
+		return false, nil
+	})
+	if err != nil {
+		t.Fatalf("Failed to wait for Pods with the latest Spec to be created: %v", err)
+	}
+
+	validateDaemonSetCollisionCount(dsClient, ds.Name, orgCollisionCount+1, t)
+}