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docker
Kostas Karkaletsis
Kostas Karkaletsis

Reputation: 401

Can I maintain the state of a docker container without commiting

I have a docker container running and would like to know if I can save its state without commiting it. For example: 1. Start container 2. Create a new file inside it 3. Exit container 4. Start container

Can the file still exist in this container without running docker commit before exiting.

Upvotes: 1

Views: 1302

Answers (1)

Farhad Farahi
Farhad Farahi

Reputation: 39387

Docker's stopped, exited Containers, Maintain files and changes in container's writable AUFS layer. Please note this layer will be removed when the container is removed.

POC:

sudo docker run -it --name test debian:jessie /bin/bash
root@3d01feb251bd:/# touch farhad
root@3d01feb251bd:/# exit

sudo docker ps -a
CONTAINER ID        IMAGE               COMMAND                  CREATED             STATUS                     PORTS               NAMES
3d01feb251bd        debian:jessie       "/bin/bash"              16 seconds ago      Exited (0) 7 seconds ago                       test

sudo docker start test

sudo docker ps
CONTAINER ID        IMAGE               COMMAND             CREATED             STATUS              PORTS               NAMES
3d01feb251bd        debian:jessie       "/bin/bash"         31 seconds ago      Up 8 seconds                            test

sudo docker exec -it test /bin/bash
root@3d01feb251bd:/# ls
bin  boot  dev  etc  farhad  home  lib  lib64  media  mnt  opt  proc  root  run  sbin  srv  sys  tmp  usr  var

As you can see the file I touched before exiting the container is still there.

Upvotes: 3

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