Docker starts a container on every system startup (debian) but I didn't create a service to do so. How can I prevent docker from doing that?
Docker will autostart any container with a RestartPolicy of 'always' when the docker service initially starts. You won't find any evidence of this within cron or any other normal system startup scripts; you'll have to dig into the container configuration to find it.
docker inspect my-container
(Look for RestartPolicy in the output. You can also use grep: docker inspect my-container | grep RestartPolicy -A 3)
I've mostly had this situation occur when a container was created with --restart always, and the situation later changed such that I no longer wanted this to happen.
After docker 1.11, this is easy to fix
docker update --restart=no my-container
Original answer is here: docker - how do you disable auto-restart on a container?