Document the workaround for https://bugzilla.redhat.com/show_bug.cgi?id=1873641:

Restic does not appear to respect the supplementalgroups of a namespace (https://docs.openshift.com/container-platform/3.11/install_config/persistent_storage/pod_security_context.html#supplemental-groups)

After changing permissions on NFS side, can run stage with copy successfully, but should not be required as supplementalgroup is set on the nfs and the stage pod is respecting it.

Fails with the following error:
backup=openshift-migration/<backup_id> controller=pod-volume-backup error="fork/exec /usr/bin/restic: permission denied" error.file="/go/src/github.com/vmware-tanzu/velero/pkg/controller/pod_volume_backup_controller.go:280" error.function="github.com/vmware-tanzu/velero/pkg/controller.(*podVolumeBackupController).processBackup" logSource="pkg/controller/pod_volume_backup_controller.go:280" name=<backup_id> namespace=openshift-migration

Solution

https://bugzilla.redhat.com/show_bug.cgi?id=1873641#c13

Dylan's PR: https://github.com/konveyor/mig-operator/pull/442