Supervisord

Run bamboo and haproxy separately in supervisord in docker container.
failure of bamboo won't have affect on haproxy instance and bamboo can meanwhile safely restart.
Not quite agree on the blog post, it also has other issue with fifo...

You will have to configure logrotate or central log collection agent on production Docker hosts anyway. I also prefer when user build/run this docker image, they get some feedback directly without going through so many layers. This is important.

What I suggest is the other way round - having debug enabled by default, you can have a custom supervisor configuration, or implement a log disabled environment variable.