"Using an external DNS service", "Method B" is flawed

[ralfbergs]

If you want or have to use an external DNS service, according to the official documentation you can use either of two methods.

However, method B, using an override file, described on that page doesn't work.

As described in the Docker docs, for the multi-value option dns, Compose concatenates both sets of values, the set of values in docker-compose.yml and the set of values in docker-compose.override.yml.

This has the effect that DNS server defined in docker-compose.yml (${IPV4_NETWORK:-172.22.1}.254, which refers to the "Unbound" container) is the first item in the resulting set, and the server defined in docker-compose.override.yml is the second item. So as long as the Unbound container is running, Unbound will still be used as the DNS service, and not the one you desire. :-(