diff --git a/sessions-backup/README.md b/sessions-backup/README.md
index c20444d..606ca1d 100644
--- a/sessions-backup/README.md
+++ b/sessions-backup/README.md
@@ -7,3 +7,13 @@ Files are named using
 ```shell
 "/var/backup/lemonldap-ng/$(date --utc +'%F_%H:%M:%S')-sessions-backup.json"
 ```
+
+## Configuration
+
+See [yadd/lemonldap-ng-base](https://github.com/guimard/llng-docker/blob/master/base/README.md#readme).
+
+You can restrict the backup to a particular scope using `BACKUP` environment
+variable:
+
+* `BACKUP=persistent`: only "persistent" sessions are saved
+* `BACKUP=refresh_tokens`: only OIDC refresh tokens are saved