add backup label

compose.yml

@@ -51,6 +51,11 @@ services:
       start_period: 1m
   rallly_db:
     image: postgres:14.8
+    deploy:
+        labels:
+          backupbot.backup: "true"
+          backupbot.backup.pre-hook: "PGPASSWORD=$$(cat /run/secrets/db_password) pg_dump -U postgres $${POSTGRES_DB} > /var/lib/postgresql/data/backup.sql"
+          backupbot.backup.post-hook: "rm -rf /var/lib/postgresql/data/backup.sql"
     volumes:
       - db-data:/var/lib/postgresql/data
     secrets: