add backupbot labels

compose.yml

@@ -72,6 +72,12 @@ services:
       - db_password
     networks:
       - internal
+    deploy:
+      labels:
+          backupbot.backup: "true"
+          backupbot.backup.pre-hook: "mkdir -p /tmp/backup/ && PGPASSWORD=$$(cat $${POSTGRES_PASSWORD_FILE}) pg_dump -U $${POSTGRES_USER} $${POSTGRES_DB} > /tmp/backup/backup.sql"
+          backupbot.backup.post-hook: "rm -rf /tmp/backup"
+          backupbot.backup.path: "/tmp/backup/"
 volumes:
   postgres:
   codimd_uploads: