"...since the normal filesystem inside the container is ephemeral." Not by default: # docker run -i -t ubuntu bash root@48dbef418f4c:/# echo foo > /bar

"...since the normal filesystem inside the container is ephemeral." Not by default: # docker run -i -t ubuntu bash root@48dbef418f4c:/# echo foo > /bar root@48dbef418f4c:/# exit # docker restart 48dbef418f4c 48dbef418f4c # docker attach 48dbef418f4c root@48dbef418f4c:/# cat /bar foo root@48dbef418f4c:/# Docker won't delete a container unless you tell it to.