Keeping a clean docker environment, taken from http://www.carlboettiger.info/2014/08/29/docker-notes

docker_cleanup.md

Keeping a clean docker environment run interactive containers with --rm flag to avoid having to remove them later.

Remove all stopped containers:

$ docker rm $(docker ps -a | grep Exited | awk '{print $1}')

Clean up un-tagged docker images:
$ docker rmi $(docker images -q --filter "dangling=true")

Stop and remove all containers (including running containers!)
$ docker rm -f $(docker ps -a -q)