This seems to work, Ubuntu is hoarding port 53 though even though local services are shut off.

Config/DNS/docker-compose.yml

@@ -10,6 +10,14 @@ version: '3'
 services:
   app:
     build: ./
-    restart: always
+    restart: on-failure
     ports:
       - "53:53"
+    command: |
+      /bin/sh -c '
+        while :
+        do
+          sleep 8h & wait $${!}
+          service dnsmasq restart
+        done
+      '