Tolerate apiserver being older than controller-manager

pkg/controller/volume/persistentvolume/index.go

@@ -259,22 +259,23 @@ func findMatchingVolume(
 }
 
 // checkVolumeModeMismatches is a convenience method that checks volumeMode for PersistentVolume
-// and PersistentVolumeClaims along with making sure that the feature gate BlockVolume is enabled.
+// and PersistentVolumeClaims
 func checkVolumeModeMismatches(pvcSpec *v1.PersistentVolumeClaimSpec, pvSpec *v1.PersistentVolumeSpec) (bool, error) {
-	if utilfeature.DefaultFeatureGate.Enabled(features.BlockVolume) {
-		if pvSpec.VolumeMode != nil && pvcSpec.VolumeMode != nil {
-			requestedVolumeMode := *pvcSpec.VolumeMode
-			pvVolumeMode := *pvSpec.VolumeMode
-			return requestedVolumeMode != pvVolumeMode, nil
-		} else {
-			// This also should return an error, this means that
-			// the defaulting has failed.
-			return true, fmt.Errorf("api defaulting for volumeMode failed")
-		}
-	} else {
-		// feature gate is disabled
+	if !utilfeature.DefaultFeatureGate.Enabled(features.BlockVolume) {
 		return false, nil
 	}
+
+	// In HA upgrades, we cannot guarantee that the apiserver is on a version >= controller-manager.
+	// So we default a nil volumeMode to filesystem
+	requestedVolumeMode := v1.PersistentVolumeFilesystem
+	if pvcSpec.VolumeMode != nil {
+		requestedVolumeMode = *pvcSpec.VolumeMode
+	}
+	pvVolumeMode := v1.PersistentVolumeFilesystem
+	if pvSpec.VolumeMode != nil {
+		pvVolumeMode = *pvSpec.VolumeMode
+	}
+	return requestedVolumeMode != pvVolumeMode, nil
 }
 
 // findBestMatchForClaim is a convenience method that finds a volume by the claim's AccessModes and requests for Storage

pkg/controller/volume/persistentvolume/index_test.go

@@ -1038,6 +1038,29 @@ func createVolumeModeFilesystemTestVolume() *v1.PersistentVolume {
 	}
 }
 
+func createVolumeModeNilTestVolume() *v1.PersistentVolume {
+	return &v1.PersistentVolume{
+		ObjectMeta: metav1.ObjectMeta{
+			UID:  "local-1",
+			Name: "nil-mode",
+		},
+		Spec: v1.PersistentVolumeSpec{
+			Capacity: v1.ResourceList{
+				v1.ResourceName(v1.ResourceStorage): resource.MustParse("10G"),
+			},
+			PersistentVolumeSource: v1.PersistentVolumeSource{
+				Local: &v1.LocalVolumeSource{},
+			},
+			AccessModes: []v1.PersistentVolumeAccessMode{
+				v1.ReadWriteOnce,
+			},
+		},
+		Status: v1.PersistentVolumeStatus{
+			Phase: v1.VolumeAvailable,
+		},
+	}
+}
+
 func createTestVolOrderedIndex(pv *v1.PersistentVolume) persistentVolumeOrderedIndex {
 	volFile := newPersistentVolumeOrderedIndex()
 	volFile.store.Add(pv)
@@ -1081,6 +1104,36 @@ func TestVolumeModeCheck(t *testing.T) {
 			pvc:                makeVolumeModePVC("8G", &filesystemMode, nil),
 			enableBlock:        true,
 		},
+		"feature enabled - pvc filesystem and pv nil": {
+			isExpectedMismatch: false,
+			vol:                createVolumeModeNilTestVolume(),
+			pvc:                makeVolumeModePVC("8G", &filesystemMode, nil),
+			enableBlock:        true,
+		},
+		"feature enabled - pvc nil and pv filesytem": {
+			isExpectedMismatch: false,
+			vol:                createVolumeModeFilesystemTestVolume(),
+			pvc:                makeVolumeModePVC("8G", nil, nil),
+			enableBlock:        true,
+		},
+		"feature enabled - pvc nil and pv nil": {
+			isExpectedMismatch: false,
+			vol:                createVolumeModeNilTestVolume(),
+			pvc:                makeVolumeModePVC("8G", nil, nil),
+			enableBlock:        true,
+		},
+		"feature enabled - pvc nil and pv block": {
+			isExpectedMismatch: true,
+			vol:                createVolumeModeBlockTestVolume(),
+			pvc:                makeVolumeModePVC("8G", nil, nil),
+			enableBlock:        true,
+		},
+		"feature enabled - pvc block and pv nil": {
+			isExpectedMismatch: true,
+			vol:                createVolumeModeNilTestVolume(),
+			pvc:                makeVolumeModePVC("8G", &blockMode, nil),
+			enableBlock:        true,
+		},
 		"feature disabled - pvc block and pv filesystem": {
 			isExpectedMismatch: false,
 			vol:                createVolumeModeFilesystemTestVolume(),