issue 6734: spread backup pod evenly

Signed-off-by: Lyndon-Li <lyonghui@vmware.com>

pkg/controller/backup_controller.go

@@ -540,8 +540,8 @@ func (b *backupReconciler) validateAndGetSnapshotLocations(backup *velerov1api.B
 	if len(errors) > 0 {
 		return nil, errors
 	}
-	allLocations := &velerov1api.VolumeSnapshotLocationList{}
-	err := b.kbClient.List(context.Background(), allLocations, &kbclient.ListOptions{Namespace: backup.Namespace, LabelSelector: labels.Everything()})
+	vsls := &velerov1api.VolumeSnapshotLocationList{}
+	err := b.kbClient.List(context.Background(), vsls, &kbclient.ListOptions{Namespace: backup.Namespace, LabelSelector: labels.Everything()})
 	if err != nil {
 		errors = append(errors, fmt.Sprintf("error listing volume snapshot locations: %v", err))
 		return nil, errors
@@ -549,8 +549,8 @@ func (b *backupReconciler) validateAndGetSnapshotLocations(backup *velerov1api.B
 
 	// build a map of provider->list of all locations for the provider
 	allProviderLocations := make(map[string][]*velerov1api.VolumeSnapshotLocation)
-	for i := range allLocations.Items {
-		loc := allLocations.Items[i]
+	for i := range vsls.Items {
+		loc := vsls.Items[i]
 		allProviderLocations[loc.Spec.Provider] = append(allProviderLocations[loc.Spec.Provider], &loc)
 	}
 

pkg/controller/backup_deletion_controller.go

@@ -570,7 +570,7 @@ func (r *backupDeletionReconciler) patchDeleteBackupRequest(ctx context.Context,
 }
 
 func (r *backupDeletionReconciler) patchBackup(ctx context.Context, backup *velerov1api.Backup, mutate func(*velerov1api.Backup)) (*velerov1api.Backup, error) {
-	//TODO: The patchHelper can't be used here because the `backup/xxx/status` does not exist, until the bakcup resource is refactored
+	//TODO: The patchHelper can't be used here because the `backup/xxx/status` does not exist, until the backup resource is refactored
 
 	// Record original json
 	oldData, err := json.Marshal(backup)

pkg/exposer/csi_snapshot.go

@@ -361,6 +361,12 @@ func (e *csiSnapshotExposer) createBackupPod(ctx context.Context, ownerObject co
 	var gracePeriod int64 = 0
 	volumeMounts, volumeDevices := kube.MakePodPVCAttachment(volumeName, backupPVC.Spec.VolumeMode)
 
+	if label == nil {
+		label = make(map[string]string)
+	}
+
+	label[podGroupLabel] = podGroupSnapshot
+
 	pod := &corev1.Pod{
 		ObjectMeta: metav1.ObjectMeta{
 			Name:      podName,
@@ -377,6 +383,18 @@ func (e *csiSnapshotExposer) createBackupPod(ctx context.Context, ownerObject co
 			Labels: label,
 		},
 		Spec: corev1.PodSpec{
+			TopologySpreadConstraints: []corev1.TopologySpreadConstraint{
+				{
+					MaxSkew:           1,
+					TopologyKey:       "kubernetes.io/hostname",
+					WhenUnsatisfiable: corev1.ScheduleAnyway,
+					LabelSelector: &metav1.LabelSelector{
+						MatchLabels: map[string]string{
+							podGroupLabel: podGroupSnapshot,
+						},
+					},
+				},
+			},
 			Containers: []corev1.Container{
 				{
 					Name:            containerName,

pkg/exposer/types.go

@@ -23,6 +23,8 @@ import (
 const (
 	AccessModeFileSystem = "by-file-system"
 	AccessModeBlock      = "by-block-device"
+	podGroupLabel        = "velero.io/exposer-pod-group"
+	podGroupSnapshot     = "snapshot-exposer"
 )
 
 // ExposeResult defines the result of expose.