Here’s a patch -
https://github.com/discourse/discourse_docker/pull/438
With that patch applied, and the docker_args key set in the container definition, the final docker run argument vector looks something like this:
/usr/bin/docker run --shm-size=512m -d --restart=always -e ... -h saj-launcher-testing-app -e DOCKER_HOST_IP=172.17.0.1 --name app -t -p 80:80 -p 443:443 -v /var/discourse/shared/standalone:/shared -v /var/discourse/shared/standalone/log/var-log:/var/log --mac-address 02:07:fa:c6:c4:82 --network foonet local_discourse/app /sbin/boot