fix issue#2413 by treating namespaces with exclude label as excludedNamespaces

Signed-off-by: allenxu404 <qix2@vmware.com>

changelogs/unreleased/5178-allenxu404

@@ -0,0 +1,2 @@
+Treat namespaces with exclude label as excludedNamespaces
+Related issue: #2413

pkg/controller/backup_controller.go

@@ -70,6 +70,7 @@ import (
 	"github.com/vmware-tanzu/velero/pkg/util/logging"
 	"github.com/vmware-tanzu/velero/pkg/volume"
 
+	corev1api "k8s.io/api/core/v1"
 	kbclient "sigs.k8s.io/controller-runtime/pkg/client"
 )
 
@@ -257,7 +258,6 @@ func (c *backupController) processBackup(key string) error {
 
 	log.Debug("Preparing backup request")
 	request := c.prepareBackupRequest(original)
-
 	if len(request.Status.ValidationErrors) > 0 {
 		request.Status.Phase = velerov1api.BackupPhaseFailedValidation
 	} else {
@@ -436,6 +436,15 @@ func (c *backupController) prepareBackupRequest(backup *velerov1api.Backup) *pkg
 	request.Annotations[velerov1api.SourceClusterK8sMajorVersionAnnotation] = c.discoveryHelper.ServerVersion().Major
 	request.Annotations[velerov1api.SourceClusterK8sMinorVersionAnnotation] = c.discoveryHelper.ServerVersion().Minor
 
+	// Add namespaces with label velero.io/exclude-from-backup=true into request.Spec.ExcludedNamespaces
+	// Essentially, adding the label velero.io/exclude-from-backup=true to a namespace would be equivalent to setting spec.ExcludedNamespaces
+	namespaces, excludeLabel := corev1api.NamespaceList{}, "velero.io/exclude-from-backup"
+	if err := c.kbClient.List(context.Background(), &namespaces, kbclient.MatchingLabels{excludeLabel: "true"}); err == nil {
+		for _, ns := range namespaces.Items {
+			request.Spec.ExcludedNamespaces = append(request.Spec.ExcludedNamespaces, ns.Name)
+		}
+	}
+
 	// validate the included/excluded resources
 	for _, err := range collections.ValidateIncludesExcludes(request.Spec.IncludedResources, request.Spec.ExcludedResources) {
 		request.Status.ValidationErrors = append(request.Status.ValidationErrors, fmt.Sprintf("Invalid included/excluded resource lists: %v", err))