not sure why but it seems I need this

core/Dockerfile

@@ -50,6 +50,7 @@ ENV INSTANCE_ID="prism-view-server_core" \
     INSTANCE_DIR="/var/www/pvs/dev/pvs_instance/" \
     COLLECTION= \
     UPLOAD_CONTAINER= \
+    DB=postgis \
     DB_USER= \
     DB_PW= \
     DB_HOST= \