Extract Prometheus metrics in EE and beyond

TrueNAS General
1

The conventional way to get prometheus metrics for docker is to add fields to the /etc/docker/daemon.json file:

{
  "metrics-addr" : "127.0.0.1:9323",
  "experimental" : true
}

But of course, TrueNAS “owns” that file and I shouldn’t just edit it (right?). So what is the supported, stable way to turn on prometheus metrics export for the built-in docker in EE and beyond?

Thanks
– perry