And for everything else that is just data processing in the stack, ephemeral storage isn't a bad thing (stops developers writing things to disk when they shouldn't).
Of course, but how? Can a docker container somehow write to the host fs? It couldn't, a few weeks ago.
[1] https://github.com/dotcloud/docker/wiki/Docker-0.5.0:-extern...
Which may or may not be the host machine, and most likely would be the machine you configure to be next door with more focus on SSDs than CPU.
I also figured, but haven't checked, that Docker will eventually support Vagrant-style shared folders. But maybe this breaks the philosophical design of a container.
As LoonyPandora said below, apparently they added shared folders recently, so I'll play with that today.
No, containers aren't ephemeral:
$ docker run -i -t base /bin/bash
root@d675bee3cbdb:/# echo 'Hello, world!' > /foo
root@d675bee3cbdb:/# exit
$ docker restart d675bee3cbdb
d675bee3cbdb
$ docker attach d675bee3cbdb
root@d675bee3cbdb:/# cat /foo
Hello, world!
root@d675bee3cbdb:/#Were you using volumes? Currently a container's volumes are reset when the container is restarted. That's fixed in master.
> Where do you get the modified id from?
In this case I just copied it from the container's command prompt. It's also available via docker ps -a:
$ docker run base sleep 1
$ docker ps -a
ID IMAGE COMMAND CREATED STATUS PORTS
041d889d7bd8 base:latest sleep 1 5 seconds ago Exit 0
$