Introduce env var INDEX for docker compose
diff --git a/korap4dnb-compose.yml b/korap4dnb-compose.yml
index 47cd8e7..b64c530 100644
--- a/korap4dnb-compose.yml
+++ b/korap4dnb-compose.yml
@@ -30,12 +30,14 @@
     user: root
     restart: "no"
   kustvakt:
+    environment:
+      - INDEX=${INDEX:-${PWD}/dnb.index}
     image: "korap/kustvakt:0.73.2"
     ports:
       - "8089:8089"
     user: root
     volumes:
-      - "${PWD}/dnb.index:/kustvakt/index:z"
+      - "${INDEX}:/kustvakt/index:z"
     profiles:
       - lite
     restart: "unless-stopped"