Docker : Use Persistent Storage2019/07/24 |
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 51e28000b0fb 2 seconds ago 1.22MB web_server latest 42e95a62ed8e 16 minutes ago 300MB srv.world/debian_apache2 latest 4295df3e5c82 22 minutes ago 243MB busybox latest db8ee88ad75f 5 days ago 1.22MB debian latest 00bf7fdd8baf 2 weeks ago 114MB # 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@da389fad6f25:/# 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 63G 4.6G 55G 8% / tmpfs tmpfs 64M 0 64M 0% /dev tmpfs tmpfs 7.9G 0 7.9G 0% /sys/fs/cgroup /dev/mapper/debian--vg-root ext4 63G 4.6G 55G 8% /storage shm tmpfs 64M 0 64M 0% /dev/shm tmpfs tmpfs 7.9G 0 7.9G 0% /proc/acpi tmpfs tmpfs 7.9G 0 7.9G 0% /sys/firmwareroot@da389fad6f25:/# echo "persistent storage" >> /storage/testfile.txt root@da389fad6f25:/# ls -l /storage total 4 -rw-r--r-- 1 root root 19 Jul 24 04:43 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 63G 4.6G 55G 8% / tmpfs tmpfs 64M 0 64M 0% /dev tmpfs tmpfs 7.9G 0 7.9G 0% /sys/fs/cgroup /dev/mapper/debian--vg-root ext4 63G 4.6G 55G 8% /mnt shm tmpfs 64M 0 64M 0% /dev/shm tmpfs tmpfs 7.9G 0 7.9G 0% /proc/acpi tmpfs tmpfs 7.9G 0 7.9G 0% /sys/firmwareroot@4526babc56ec:/# cat /mnt/testfile.txt persistent storage |
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