Why did you not use something like supervisord? I run a few containers (obviously not at yelp scale) and supervisors has been spectacular at restarting, managing,reloading,etc. It handles nginx,gunicorn,puma,tomcat, etc pretty well. Yes its python - but was that the motivation?

Also,you guys should comment on https://github.com/docker/docker/pull/5773 which is work on unprivileged systemd in docker. I think you guys can influence the bug with your experience in this.