demo: docker containers preserve data

terminal_dump.txt

amit@penguin:~$ docker run -i -t debian /bin/bash
root@338b5a0ff034:/# mkdir /usr/local/blabla
root@338b5a0ff034:/# echo hello-there >/usr/local/blabla/data
root@338b5a0ff034:/# exit
exit
amit@penguin:~$ docker ps -a
CONTAINER ID        IMAGE               COMMAND             CREATED             STATUS                     PORTS               NAMES
338b5a0ff034        debian              "/bin/bash"         32 seconds ago      Exited (0) 5 seconds ago                       stoic_goldberg
13ffee81f8cd        debian              "/bin/bash"         35 hours ago        Exited (0) 29 hours ago                        boring_kowalevski
amit@penguin:~$ docker start -a -i 338b5a0ff034
root@338b5a0ff034:/# cat /usr/local/blabla/data 
hello-there
root@338b5a0ff034:/#