Great idea. I never thought of Docker containers this way because I totally forgot that I can always mount the config to the container.

This totally changes my dev environment setup.

$ docker run -it \
    -v /etc/localtime:/etc/localtime \
    -v $HOME/.irssi:/home/user/.irssi \ # mounts irssi config in container
    --read-only \ # cool new feature in 1.5
    --name irssi \
    jess/irssi