Docker : Use Persistent Storage
2017/08/03 |
When Container is removed, data in it are also lost, so it's necessary to use external filesystem in Container as persistent storage if you need.
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[1] | For exmaple, create a Container only for using to save data as a storage server with an image busybox. |
root@dlp:~#
vi Dockerfile # create new FROM busybox MAINTAINER ServerWorld <admin@srv.world> VOLUME /storage CMD /bin/sh # build image root@dlp:~# docker build -t storage .
docker images REPOSITORY TAG IMAGE ID CREATED SIZE storage latest e5f465d60931 24 seconds ago 1.13MB web_server latest d6df7acdc0e3 7 minutes ago 296MB srv.world/deb_apache2 latest 8efc6944bf8d 2 days ago 219MB debian latest a20fd0d59cf1 10 days ago 100MB busybox latest efe10ee6727f 2 weeks ago 1.13MB # generate a Container with any name you like root@dlp:~# docker run -it --name storage_server storage / # exit
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[2] | To use the Container above as a Storage Server from other Containers, add an option [--volumes-from]. |
root@dlp:~#
root@d9d1f5e41206:/# docker run -it --name debian_server --volumes-from storage_server debian /bin/bash df -hT Filesystem Type Size Used Avail Use% Mounted on overlay overlay 71G 2.0G 65G 3% / tmpfs tmpfs 4.0G 0 4.0G 0% /dev tmpfs tmpfs 4.0G 0 4.0G 0% /sys/fs/cgroup /dev/mapper/debian--vg-root ext4 71G 2.0G 65G 3% /storage shm tmpfs 64M 0 64M 0% /dev/shm tmpfs tmpfs 4.0G 0 4.0G 0% /sys/firmwareroot@d9d1f5e41206:/# echo "persistent storage" >> /storage/testfile.txt root@d9d1f5e41206:/# ls -l /storage total 4 -rw-r--r-- 1 root root 19 Aug 4 02:49 testfile.txt |
[3] | Make sure datas are saved to run a Container of Storage Server like follows. |
root@dlp:~# docker start storage_server root@dlp:~# docker exec -it storage_server cat /storage/testfile.txt persistent storage |
[4] | For other way to save data in external filesystem, it's possible to mount a directory on Docker Host into Containers. |
# create a directory root@dlp:~# mkdir -p /var/lib/docker/disk01 root@dlp:~# echo "persistent storage" >> /var/lib/docker/disk01/testfile.txt
# run a Container with mounting the directory above on /mnt root@dlp:~# docker run -it -v /var/lib/docker/disk01:/mnt debian /bin/bash
df -hT Filesystem Type Size Used Avail Use% Mounted on overlay overlay 71G 2.0G 65G 3% / tmpfs tmpfs 4.0G 0 4.0G 0% /dev tmpfs tmpfs 4.0G 0 4.0G 0% /sys/fs/cgroup /dev/mapper/debian--vg-root ext4 71G 2.0G 65G 3% /mnt shm tmpfs 64M 0 64M 0% /dev/shm tmpfs tmpfs 4.0G 0 4.0G 0% /sys/firmwareroot@aea7f8b758d4:/# cat /mnt/testfile.txt persistent storage |