docker-lvm-plugin man page

docker-lvm-plugin — Docker Volume Driver for lvm volumes

Synopsis

docker-lvm-plugin [-debug] [-version]

Description

This plugin can be used to create lvm volumes of specified size, which can then be bind mounted into the container using docker run command.

Usage

Start the docker daemon before starting the docker-lvm-plugin daemon. You can start docker daemon using command:

systemctl start docker 

Once docker daemon is up and running, you can start docker-lvm-plugin daemon using command:

systemctl start docker-lvm-plugin

docker-lvm-plugin daemon is on-demand socket activated. Running docker volume ls command will automatically start the daemon.

Since logical volumes (lv's) are based on a volume group, it is the responsibility of the user (administrator) to provide a volume group name. You can choose an existing volume group name by listing volume groups on your system using vgs command OR create a new volume group using vgcreate command. e.g.

vgcreate vg1 /dev/hda 

where /dev/hda is your partition or whole disk on which physical volumes were created.

Add this volume group name in the config file.

/etc/docker/docker-lvm-plugin

The docker-lvm-plugin also supports the creation of thinly-provisioned volumes. To create a thinly-provisioned volume, a user (administrator) must first create a thin pool using the lvcreate command.

lvcreate -L 10G -T vg1/mythinpool

This will create a thinpool named mythinpool of size 10G under volume group vg1. NOTE: thinpools are special kind of logical volumes carved out of the volume group. Hence in the above example, to create the thinpool mythinpool you must have atleast 10G of freespace in volume group vg1.

Options

-debug=true|false

Enable debug logging. Default is false. -version=true|false
 Print version information and quit. Default is false.

Examples

Volume Creation

docker volume create -d lvm --opt size=0.2G --name foobar

This will create a lvm volume named foobar of size 208 MB (0.2 GB).

docker volume create -d lvm --opt size=0.2G --opt thinpool=mythinpool --name thin_vol

This will create a thinly-provisioned lvm volume named thin_vol in mythinpool.

docker volume create -d lvm --opt snapshot=foobar --opt size=100M --name foobar_snapshot

This will create a snapshot volume of foobar named foobar_snapshot. For thin snapshots, use the same command above but don't specify a size.

docker volume create -d lvm --opt size=0.2G --opt keyfile=/root/key.bin --name crypt_vol

This will create a LUKS encrypted lvm volume named crypt_vol with the contents of /root/key.bin as a binary passphrase. Snapshots of encrypted volumes use the same key file. The key file must be present when the volume is created, and when it is mounted to a container.

Volume List

docker volume ls

This will list volumes created by all docker drivers including the default driver (local).

Volume Inspect

docker volume inspect foobar

This will inspect foobar and return a JSON. [
   {
       "Driver": "lvm",
       "Labels": {},
       "Mountpoint": "/var/lib/docker-lvm-plugin/foobar",
       "Name": "foobar",
       "Options": {
           "size": "0.2G"
       },
       "Scope": "local"
   } ]

Volume Removal

docker volume rm foobar

This will remove lvm volume foobar.

Bind Mount lvm volume inside the container

docker run -it -v foobar:/home fedora /bin/bash

This will bind mount the logical volume foobar into the home directory of the container.

Info

Shishir Mahajan FEBRUARY 2016