make PVProvider optional in server config; disallow snap/restore PVs when not provided

Signed-off-by: Steve Kriss <steve@heptio.com>

pkg/controller/backup_controller.go

@@ -49,9 +49,10 @@ import (
 const backupVersion = 1
 
 type backupController struct {
-	backupper     backup.Backupper
-	backupService cloudprovider.BackupService
-	bucket        string
+	backupper      backup.Backupper
+	backupService  cloudprovider.BackupService
+	bucket         string
+	allowSnapshots bool
 
 	lister       listers.BackupLister
 	listerSynced cache.InformerSynced
@@ -68,11 +69,13 @@ func NewBackupController(
 	backupper backup.Backupper,
 	backupService cloudprovider.BackupService,
 	bucket string,
+	allowSnapshots bool,
 ) Interface {
 	c := &backupController{
-		backupper:     backupper,
-		backupService: backupService,
-		bucket:        bucket,
+		backupper:      backupper,
+		backupService:  backupService,
+		bucket:         bucket,
+		allowSnapshots: allowSnapshots,
 
 		lister:       backupInformer.Lister(),
 		listerSynced: backupInformer.Informer().HasSynced,
@@ -297,6 +300,10 @@ func (controller *backupController) getValidationErrors(itm *api.Backup) []strin
 		validationErrors = append(validationErrors, fmt.Sprintf("Invalid included/excluded namespace lists: %v", err))
 	}
 
+	if !controller.allowSnapshots && itm.Spec.SnapshotVolumes {
+		validationErrors = append(validationErrors, "Server is not configured for PV snapshots")
+	}
+
 	return validationErrors
 }