OADP-3954 ImageStreamTag Update

Author: shdeshpa07

backup_and_restore/application_backup_and_restore/backing_up_and_restoring/restoring-applications.adoc

@@ -13,3 +13,14 @@ You can create restore hooks to run commands in a container in a pod by editing
 include::modules/oadp-review-backup-restore.adoc[leveloffset=+1]
 include::modules/oadp-creating-restore-cr.adoc[leveloffset=+1]
 include::modules/oadp-creating-restore-hooks.adoc[leveloffset=+1]
+[IMPORTANT]
+====
+include::snippets/oadp-image-stream-tag-trigger.adoc[leveloffset=+1]
+====
+
+[role="_additional-resources"]
+.Additional resources
+
+* xref:../../../openshift_images/triggering-updates-on-imagestream-changes.adoc#triggering-updates-on-imagestream-changes[Triggering updates on image stream changes]
+
+

snippets/oadp-image-stream-tag-trigger.adoc

@@ -0,0 +1,31 @@
+
+//This snippet appears in the following assemblies:
+//
+//backup_and_restore/application_backup_and_restore/backing_up_and_restoring/restoring-applications.adoc
+//OADP 1.4.1 Release Notes
+
+:_mod-docs-content-type: SNIPPET
+
+During a File System Backup (FSB) restore operation, a `Deployment` resource referencing an `ImageStream` is not restored properly. The restored pod that runs the FSB, and the `postHook` is terminated prematurely.
+
+This happens because, during the restore operation, OpenShift controller updates the `spec.template.spec.containers[0].image` field in the `Deployment` resource with an updated `ImageStreamTag` hash. The update triggers the rollout of a new pod, terminating the pod on which `velero` runs the FSB and the post restore hook. For more information about image stream trigger, see "Triggering updates on image stream changes".
+
+The workaround for this behavior is a two-step restore process:
+
+. First, perform a restore excluding the `Deployment` resources, for example:
++
+[source,terminal]
+----
+$ velero restore create <RESTORE_NAME> \
+  --from-backup <BACKUP_NAME> \
+  --exclude-resources=deployment.apps
+----
+
+. After the first restore is successful, perform a second restore by including these resources, for example:
++
+[source,terminal]
+----
+$ velero restore create <RESTORE_NAME> \
+  --from-backup <BACKUP_NAME> \
+  --include-resources=deployment.apps
+----