Simplify Cluster webhook

Signed-off-by: Stefan Büringer [email protected]

Author: sbueringer

internal/webhooks/cluster.go

@@ -79,8 +79,6 @@ type Cluster struct {
 var _ webhook.CustomDefaulter = &Cluster{}
 var _ webhook.CustomValidator = &Cluster{}
 
-var errClusterClassNotReconciled = errors.New("ClusterClass is not successfully reconciled")
-
 // Default satisfies the defaulting webhook interface.
 func (webhook *Cluster) Default(ctx context.Context, obj runtime.Object) error {
 	// We gather all defaulting errors and return them together.
@@ -109,14 +107,15 @@ func (webhook *Cluster) Default(ctx context.Context, obj runtime.Object) error {
 			return apierrors.NewInvalid(clusterv1.GroupVersion.WithKind("Cluster").GroupKind(), cluster.Name, allErrs)
 		}
 
-		clusterClass, err := webhook.pollClusterClassForCluster(ctx, cluster)
+		clusterClass, clusterClassNotReconciled, clusterClassNotFound, err := webhook.pollClusterClassForCluster(ctx, cluster)
 		if err != nil {
-			// If the ClusterClass can't be found or is not up to date ignore the error.
-			if apierrors.IsNotFound(err) || errors.Is(err, errClusterClassNotReconciled) {
-				return nil
-			}
 			return apierrors.NewInternalError(errors.Wrapf(err, "Cluster %s can't be defaulted. ClusterClass %s can not be retrieved", cluster.Name, cluster.GetClassKey().Name))
 		}
+		if clusterClassNotReconciled || clusterClassNotFound {
+			// If the ClusterClass can't be found or is not reconciled, return as we shouldn't
+			// default and validate variables in that case.
+			return nil
+		}
 
 		// Validate cluster class variables transitions that may be enforced by CEL validation rules on variables.
 		// If no request found in context, then this has not come via a webhook request, so skip validation of old cluster.
@@ -312,39 +311,34 @@ func (webhook *Cluster) validateTopology(ctx context.Context, oldCluster, newClu
 	}
 
 	// Get the ClusterClass referenced in the Cluster.
-	clusterClass, warnings, clusterClassPollErr := webhook.validateClusterClassExistsAndIsReconciled(ctx, newCluster)
-	// If the error is anything other than "NotFound" or "NotReconciled" return all errors.
-	if clusterClassPollErr != nil && (!apierrors.IsNotFound(clusterClassPollErr) && !errors.Is(clusterClassPollErr, errClusterClassNotReconciled)) {
-		allErrs = append(
-			allErrs, field.InternalError(
-				fldPath.Child("class"),
-				clusterClassPollErr))
-		return allWarnings, allErrs
+	// Note: If the ClusterClass is not found, a warning and no err is returned and the clusterClass is nil.
+	// Note: If the ClusterClass is not reconciled, a warning and no err is returned and the clusterClass is returned.
+	clusterClass, warnings, err := webhook.validateClusterClassExistsAndIsReconciled(ctx, newCluster)
+	if err != nil {
+		return allWarnings, append(allErrs, field.InternalError(fldPath.Child("class"), err))
 	}
-
-	// Add the warnings if no error was returned.
 	allWarnings = append(allWarnings, warnings...)
 
-	// If there's no error validate the Cluster based on the ClusterClass.
-	if clusterClassPollErr == nil {
+	// If we could get the ClusterClass validate the Cluster based on the ClusterClass.
+	if clusterClass != nil {
 		allErrs = append(allErrs, ValidateClusterForClusterClass(newCluster, clusterClass)...)
 	}
 
-	// Validate the Cluster and associated ClusterClass' autoscaler annotations.
+	// Validate the Cluster and associated ClusterClass' autoscaler annotations
+	// Note: ClusterClass validation is only run if clusterClass is not nil.
 	allErrs = append(allErrs, validateAutoscalerAnnotationsForCluster(newCluster, clusterClass)...)
 
 	if oldCluster != nil { // On update
-		// The ClusterClass must exist to proceed with update validation. Return an error if the ClusterClass was
-		// not found.
-		if apierrors.IsNotFound(clusterClassPollErr) {
+		// The ClusterClass must exist to proceed with update validation. Return an error if the ClusterClass was not found.
+		if clusterClass == nil {
 			allErrs = append(
 				allErrs, field.InternalError(
 					fldPath.Child("class"),
-					clusterClassPollErr))
+					errors.Errorf("ClusterClass %s not found", newCluster.GetClassKey())))
 			return allWarnings, allErrs
 		}
 
-		// Topology or Class can not be added on update unless ClusterTopologyUnsafeUpdateClassNameAnnotation is set.
+		// Topology or Class can not be added or update unless ClusterTopologyUnsafeUpdateClassNameAnnotation is set.
 		if !oldCluster.Spec.Topology.IsDefined() || oldCluster.GetClassKey().Name == "" {
 			if _, ok := newCluster.Annotations[clusterv1.ClusterTopologyUnsafeUpdateClassNameAnnotation]; ok {
 				return allWarnings, allErrs
@@ -402,29 +396,21 @@ func (webhook *Cluster) validateTopology(ctx context.Context, oldCluster, newClu
 
 		// If the ClusterClass referenced in the Topology has changed compatibility checks are needed.
 		if oldCluster.GetClassKey() != newCluster.GetClassKey() {
-			if clusterClassPollErr != nil {
-				allErrs = append(
-					allErrs, field.Forbidden(
-						fldPath.Child("class"),
-						fmt.Sprintf("cannot rebase to ClusterClass %q: %s",
-							newCluster.GetClassKey(), clusterClassPollErr.Error())))
-				// Return early with errors if the new ClusterClass can't be retrieved.
-				return allWarnings, allErrs
-			}
-
 			// Check to see if the ClusterClass referenced in the old version of the Cluster exists.
-			oldClusterClass, err := webhook.pollClusterClassForCluster(ctx, oldCluster)
-			if err != nil {
+			// Return early with errors if the old ClusterClass can't be retrieved.
+			oldClusterClass := &clusterv1.ClusterClass{}
+			if err := webhook.Client.Get(ctx, oldCluster.GetClassKey(), oldClusterClass); err != nil {
 				allErrs = append(
 					allErrs, field.Forbidden(
 						fldPath.Child("class"),
 						fmt.Sprintf("valid ClusterClass with name %q could not be retrieved, change from class %[1]q to class %q cannot be validated. Error: %s",
 							oldCluster.GetClassKey(), newCluster.GetClassKey(), err.Error())))
-
-				// Return early with errors if the old ClusterClass can't be retrieved.
 				return allWarnings, allErrs
 			}
 
+			// Note: We don't care if the old ClusterClass is reconciled as the validation below doesn't need it
+			// and we want to allow to rebase away from a broken ClusterClass.
+
 			// Check if the new and old ClusterClasses are compatible with one another.
 			allErrs = append(allErrs, check.ClusterClassesAreCompatible(oldClusterClass, clusterClass)...)
 		}
@@ -926,76 +912,80 @@ func ValidateClusterForClusterClass(cluster *clusterv1.Cluster, clusterClass *cl
 
 // validateClusterClassExistsAndIsReconciled will try to get the ClusterClass referenced in the Cluster. If it does not exist or is not reconciled it will add a warning.
 // In any other case it will return an error.
-func (webhook *Cluster) validateClusterClassExistsAndIsReconciled(ctx context.Context, newCluster *clusterv1.Cluster) (*clusterv1.ClusterClass, admission.Warnings, error) {
+func (webhook *Cluster) validateClusterClassExistsAndIsReconciled(ctx context.Context, newCluster *clusterv1.Cluster) (_ *clusterv1.ClusterClass, _ admission.Warnings, _ error) {
 	var allWarnings admission.Warnings
-	clusterClass, clusterClassPollErr := webhook.pollClusterClassForCluster(ctx, newCluster)
-	if clusterClassPollErr != nil {
-		// Add a warning if the Class does not exist or if it has not been successfully reconciled.
-		switch {
-		case apierrors.IsNotFound(clusterClassPollErr):
-			allWarnings = append(allWarnings,
-				fmt.Sprintf(
-					"Cluster refers to ClusterClass %s, but this ClusterClass does not exist. "+
-						"Cluster topology has not been fully validated. "+
-						"The ClusterClass must be created to reconcile the Cluster", newCluster.GetClassKey()),
-			)
-		case errors.Is(clusterClassPollErr, errClusterClassNotReconciled):
-			allWarnings = append(allWarnings,
-				fmt.Sprintf(
-					"Cluster refers to ClusterClass %s, but this ClusterClass hasn't been successfully reconciled. "+
-						"Cluster topology has not been fully validated. "+
-						"Please take a look at the ClusterClass status", newCluster.GetClassKey()),
-			)
-		// If there's any other error return a generic warning with the error message.
-		default:
-			allWarnings = append(allWarnings,
-				fmt.Sprintf(
-					"Cluster refers to ClusterClass %s, but this ClusterClass could not be retrieved. "+
-						"Cluster topology has not been fully validated: %s", newCluster.GetClassKey(), clusterClassPollErr.Error()),
-			)
-		}
+	clusterClass, clusterClassNotReconciled, clusterClassNotFound, err := webhook.pollClusterClassForCluster(ctx, newCluster)
+	// Add a warning if the Class does not exist or if it has not been successfully reconciled.
+	switch {
+	case err != nil:
+		allWarnings = append(allWarnings,
+			fmt.Sprintf(
+				"Cluster refers to ClusterClass %s, but this ClusterClass could not be retrieved. "+
+					"Cluster topology has not been fully validated: %s", newCluster.GetClassKey(), err.Error()),
+		)
+	case clusterClassNotFound:
+		allWarnings = append(allWarnings,
+			fmt.Sprintf(
+				"Cluster refers to ClusterClass %s, but this ClusterClass does not exist. "+
+					"Cluster topology has not been fully validated. "+
+					"The ClusterClass must be created to reconcile the Cluster", newCluster.GetClassKey()),
+		)
+	case clusterClassNotReconciled:
+		allWarnings = append(allWarnings,
+			fmt.Sprintf(
+				"Cluster refers to ClusterClass %s, but this ClusterClass hasn't been successfully reconciled. "+
+					"Cluster topology has not been fully validated. "+
+					"Please take a look at the ClusterClass status", newCluster.GetClassKey()),
+		)
 	}
-	return clusterClass, allWarnings, clusterClassPollErr
+	return clusterClass, allWarnings, err
 }
 
 // pollClusterClassForCluster will retry getting the ClusterClass referenced in the Cluster for two seconds.
-func (webhook *Cluster) pollClusterClassForCluster(ctx context.Context, cluster *clusterv1.Cluster) (*clusterv1.ClusterClass, error) {
+func (webhook *Cluster) pollClusterClassForCluster(ctx context.Context, cluster *clusterv1.Cluster) (_ *clusterv1.ClusterClass, clusterClassNotReconciled, clusterClassNotFound bool, _ error) {
+	var errClusterClassNotReconciled = errors.New("ClusterClass is not successfully reconciled")
+
 	clusterClass := &clusterv1.ClusterClass{}
 	var clusterClassPollErr error
 	_ = wait.PollUntilContextTimeout(ctx, 200*time.Millisecond, 2*time.Second, true, func(ctx context.Context) (bool, error) {
 		if clusterClassPollErr = webhook.Client.Get(ctx, cluster.GetClassKey(), clusterClass); clusterClassPollErr != nil {
 			return false, nil //nolint:nilerr
 		}
 
-		if clusterClassPollErr = clusterClassIsReconciled(clusterClass); clusterClassPollErr != nil {
-			return false, nil //nolint:nilerr
+		if !clusterClassIsReconciled(clusterClass) {
+			clusterClassPollErr = errClusterClassNotReconciled
+			return false, nil
 		}
+
 		clusterClassPollErr = nil
 		return true, nil
 	})
 	if clusterClassPollErr != nil {
+		if apierrors.IsNotFound(clusterClassPollErr) {
+			return nil, false, true, nil
+		}
 		if errors.Is(clusterClassPollErr, errClusterClassNotReconciled) {
 			// Return ClusterClass if we were able to get it and it's just not reconciled.
-			return clusterClass, clusterClassPollErr
+			return clusterClass, true, false, nil
 		}
-		return nil, clusterClassPollErr
+		return nil, false, false, clusterClassPollErr
 	}
-	return clusterClass, nil
+	return clusterClass, false, false, nil
 }
 
 // clusterClassIsReconciled returns errClusterClassNotReconciled if the ClusterClass has not successfully reconciled or if the
 // ClusterClass variables have not been successfully reconciled.
-func clusterClassIsReconciled(clusterClass *clusterv1.ClusterClass) error {
+func clusterClassIsReconciled(clusterClass *clusterv1.ClusterClass) bool {
 	// If the clusterClass metadata generation does not match the status observed generation, the ClusterClass has not been successfully reconciled.
 	if clusterClass.Generation != clusterClass.Status.ObservedGeneration {
-		return errClusterClassNotReconciled
+		return false
 	}
 	// If the clusterClass does not have ClusterClassVariablesReconciled==True, the ClusterClass has not been successfully reconciled.
 	if !conditions.Has(clusterClass, clusterv1.ClusterClassVariablesReadyCondition) ||
 		conditions.IsFalse(clusterClass, clusterv1.ClusterClassVariablesReadyCondition) {
-		return errClusterClassNotReconciled
+		return false
 	}
-	return nil
+	return true
 }
 
 func validateTopologyMetadata(topology clusterv1.Topology, fldPath *field.Path) field.ErrorList {

internal/webhooks/cluster_test.go

@@ -3415,11 +3415,11 @@ func TestClusterClassPollingErrors(t *testing.T) {
 			wantErr:        false,
 		},
 		{
-			name:           "Fail on update if oldCluster ClusterClass generation does not match observedGeneration",
+			name:           "Pass on update if oldCluster ClusterClass generation does not match observedGeneration",
 			cluster:        builder.Cluster(metav1.NamespaceDefault, "cluster1").WithTopology(secondTopology).Build(),
 			oldCluster:     builder.Cluster(metav1.NamespaceDefault, "cluster1").WithTopology(topology).Build(),
 			clusterClasses: []*clusterv1.ClusterClass{ccGenerationMismatch, secondFullyReconciled},
-			wantErr:        true,
+			wantErr:        false,
 		},
 		{
 			name:           "Fail on update if old Cluster ClusterClass is not found",