Merge pull request #4358 from ywk253100/211117_pager

[cherry-pick]fix buggy pager func

changelogs/unreleased/4358-alaypatel07

@@ -0,0 +1 @@
+fix buggy pager func

pkg/backup/item_collector.go

@@ -26,7 +26,7 @@ import (
 
 	"github.com/pkg/errors"
 	"github.com/sirupsen/logrus"
-	apierrors "k8s.io/apimachinery/pkg/api/errors"
+	"k8s.io/apimachinery/pkg/api/meta"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"k8s.io/apimachinery/pkg/apis/meta/v1/unstructured"
 	"k8s.io/apimachinery/pkg/labels"
@@ -293,58 +293,49 @@ func (r *itemCollector) getResourceItems(log logrus.FieldLogger, gv schema.Group
 		if selector := r.backupRequest.Spec.LabelSelector; selector != nil {
 			labelSelector = metav1.FormatLabelSelector(selector)
 		}
-		listOptions := metav1.ListOptions{LabelSelector: labelSelector}
 
 		log.Info("Listing items")
 		unstructuredItems := make([]unstructured.Unstructured, 0)
 
 		if r.pageSize > 0 {
 			// If limit is positive, use a pager to split list over multiple requests
 			// Use Velero's dynamic list function instead of the default
-			listFunc := pager.SimplePageFunc(func(opts metav1.ListOptions) (runtime.Object, error) {
-				list, err := resourceClient.List(listOptions)
-				if err != nil {
-					return nil, err
-				}
-				return list, nil
-			})
-			listPager := pager.New(listFunc)
+			listPager := pager.New(pager.SimplePageFunc(func(opts metav1.ListOptions) (runtime.Object, error) {
+				return resourceClient.List(opts)
+			}))
 			// Use the page size defined in the server config
 			// TODO allow configuration of page buffer size
 			listPager.PageSize = int64(r.pageSize)
 			// Add each item to temporary slice
-			var items []unstructured.Unstructured
-			err := listPager.EachListItem(context.Background(), listOptions, func(object runtime.Object) error {
-				item, isUnstructured := object.(*unstructured.Unstructured)
-				if !isUnstructured {
-					// We should never hit this
-					log.Error("Got type other than Unstructured from pager func")
-					return nil
+			list, paginated, err := listPager.List(context.Background(), metav1.ListOptions{LabelSelector: labelSelector})
+			if err != nil {
+				log.WithError(errors.WithStack(err)).Error("Error listing resources")
+				continue
+			}
+			if !paginated {
+				log.Infof("list for groupResource %s was not paginated", gr)
+			}
+			err = meta.EachListItem(list, func(object runtime.Object) error {
+				u, ok := object.(*unstructured.Unstructured)
+				if !ok {
+					log.WithError(errors.WithStack(fmt.Errorf("expected *unstructured.Unstructured but got %T", u))).Error("unable to understand entry in the list")
+					return fmt.Errorf("expected *unstructured.Unstructured but got %T", u)
 				}
-				items = append(items, *item)
+				unstructuredItems = append(unstructuredItems, *u)
 				return nil
 			})
-			if statusError, isStatusError := err.(*apierrors.StatusError); isStatusError && statusError.Status().Reason == metav1.StatusReasonExpired {
-				log.WithError(errors.WithStack(err)).Error("Error paging item list. Falling back on unpaginated list")
-				unstructuredList, err := resourceClient.List(listOptions)
-				if err != nil {
-					log.WithError(errors.WithStack(err)).Error("Error listing items")
-					continue
-				}
-				items = unstructuredList.Items
-			} else if err != nil {
-				log.WithError(errors.WithStack(err)).Error("Error paging item list")
+			if err != nil {
+				log.WithError(errors.WithStack(err)).Error("unable to understand paginated list")
 				continue
 			}
-			unstructuredItems = append(unstructuredItems, items...)
 		} else {
 			// If limit is not positive, do not use paging. Instead, request all items at once
 			unstructuredList, err := resourceClient.List(metav1.ListOptions{LabelSelector: labelSelector})
-			unstructuredItems = append(unstructuredItems, unstructuredList.Items...)
 			if err != nil {
 				log.WithError(errors.WithStack(err)).Error("Error listing items")
 				continue
 			}
+			unstructuredItems = append(unstructuredItems, unstructuredList.Items...)
 		}
 
 		log.Infof("Retrieved %d items", len(unstructuredItems))