Abort rsync_backup if envar empty

.talismanrc

@@ -33,6 +33,6 @@ fileignoreconfig:
   ignore_detectors:
   - filename
 - filename: rsync_backup.sh
-  checksum: a622ec17b80f20296ee7f5a7ead28a0c49b1ead256e15deb818fba57730355de
+  checksum: bba788ae9f66264e9e902f4c50623de8b61a9ee1ea9867a350a919a48328f448
 - filename: secrets.template
   checksum: c6735d96a94ea5ce4ae1b7b3c72f2a75845539cca02664929b8025bcc07a0618

rsync_backup.sh

@@ -3,4 +3,8 @@
 # Backup script that uses rsync, taken from https://wiki.archlinux.org/index.php/Rsync#As_a_backup_utility
 # This script should be run daily with cron or a systemd timer.
 
+[ -z "$SETUP_COCKPIT_USER" ] && echo "SETUP_COCKPIT_USER was not set, quitting" && exit 1
+[ -z "$RSYNC_BACKUP_SRC" ] && echo "RSYNC_BACKUP_SRC was not set, quitting" && exit 1
+[ -z "$RSYNC_BACKUP_DEST" ] && echo "RSYNC_BACKUP_DEST was not set, quitting" && exit 1
+
 rsync -a --delete --quiet --exclude-from=/home/"$SETUP_COCKPIT_USER"/setup-cockpit/rsync_backup_excludes "$RSYNC_BACKUP_SRC" "$RSYNC_BACKUP_DEST"