fix: accept DNS_VALID
diff --git a/config-ui/nginx.conf b/config-ui/nginx.conf
index d1fcfa3..82b0244 100644
--- a/config-ui/nginx.conf
+++ b/config-ui/nginx.conf
@@ -10,7 +10,7 @@
   }
 
   location /api/ {
-    resolver ${DNS} valid=300s;
+    resolver ${DNS} valid=${DNS_VALID};
     resolver_timeout 3s;
     set $target "${DEVLAKE_ENDPOINT}";
     rewrite /api/(.*) /$1  break;
diff --git a/config-ui/nginx.sh b/config-ui/nginx.sh
index 4f92a4e..abf9185 100644
--- a/config-ui/nginx.sh
+++ b/config-ui/nginx.sh
@@ -8,6 +8,7 @@
     '
 fi
 export DNS=$(grep nameserver /etc/resolv.conf | awk '{print $2}')
+export DNS_VALID=${DNS_VALID:-300s}
 envsubst '${DEVLAKE_ENDPOINT} ${GRAFANA_ENDPOINT} ${SERVER_CONF} ${DNS}' \
     < /etc/nginx/conf.d/default.conf.tpl \
     > /etc/nginx/conf.d/default.conf