Yelp, an early adopter of Linux containers, has released an initialization system that runs inside of Docker containers, called dumb-init, designed to eliminate signaling issues that can spawn zombie processes.
The company is in the process of moving individual commands into containers so they can slowly migrate tools and infrastructure without disrupting current workflow. This requires their processes to run as if they were running in the legacy system in regards to user input, responding to signals and dying when expected.