See:
https://meta.discourse.org/t/runsv-hanging-on-docker-container-shutdown/36844/27?u=sam
Please try that out ASAP and let me know if it works, I want to roll it into the image.
Yes, we do autogenerate that file on boot per:
https://github.com/discourse/discourse_docker/blob/master/templates/web.template.yml#L26-L35