Docker : Use Persistent Storage
2017/12/21 |
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] |
This example is based on the environment that SELnux is Permissive or Disabled.
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[2] | 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 f1d05ad33204 19 seconds ago 1.13 MB srv.world/fedora_httpd latest 32918df26202 22 minutes ago 564 MB docker.io/fedora latest 422dc563ca32 5 weeks ago 252 MB docker.io/busybox latest 6ad733544a63 6 weeks ago 1.13 MB # generate a Container with any name you like [root@dlp ~]# docker run -it --name storage_server storage / # exit
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[3] | To use the Container above as a Storage Server from other Containers, add an option [--volumes-from]. |
[root@dlp ~]#
[root@087615087f7b /]# docker run -it --name fedora_server --volumes-from storage_server fedora /bin/bash df -hT Filesystem Type Size Used Avail Use% Mounted on overlay overlay 15G 2.8G 13G 19% / tmpfs tmpfs 8.9G 0 8.9G 0% /dev tmpfs tmpfs 8.9G 0 8.9G 0% /sys/fs/cgroup /dev/mapper/fedora-root xfs 15G 2.8G 13G 19% /storage shm tmpfs 64M 0 64M 0% /dev/shm tmpfs tmpfs 8.9G 0 8.9G 0% /sys/firmware[root@087615087f7b /]# echo "persistent storage" >> /storage/testfile.txt [root@087615087f7b /]# ll /storage total 4 -rw-r--r--. 1 root root 19 Dec 22 05:55 testfile.txt |
[4] | 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 |
[5] | 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 fedora /bin/bash
df -hT Filesystem Type Size Used Avail Use% Mounted on overlay overlay 15G 2.8G 13G 19% / tmpfs tmpfs 8.9G 0 8.9G 0% /dev tmpfs tmpfs 8.9G 0 8.9G 0% /sys/fs/cgroup /dev/mapper/fedora-root xfs 15G 2.8G 13G 19% /mnt shm tmpfs 64M 0 64M 0% /dev/shm tmpfs tmpfs 8.9G 0 8.9G 0% /sys/firmware[root@a8376cf9d9e5 /]# cat /mnt/testfile.txt persistent storage |