Ubuntu 14.04 LXC : share /dev/sdX of LXC host with a container

Here is how to share /dec/sdb3 of LXC host with a container.

Reference

http://askubuntu.com/questions/528161/how-to-make-a-hdd-device-file-dev-sdxy-available-in-lxc-container

root@ubuntu:~# tail -1 /etc/lsb-release

DISTRIB_DESCRIPTION="Ubuntu 14.04.3 LTS"

root@ubuntu:~# dpkg -l lxc | tail -1

ii  lxc                                                   1.0.7-0ubuntu0.9                                    amd64        Linux Containers userspace tools

[ edit fstab of a container ]

on the LXC host, edit fstab of a container "ubuntu-cn01"

root@ubuntu:~# cat /var/lib/lxc/ubuntu-cn01/fstab

/dev/sdb3 mnt/sdb3 ext4 noatime 0 0

root@ubuntu:~# grep lxc.mount /var/lib/lxc/ubuntu-cn01/config

lxc.mount.auto = cgroup

lxc.mount = /var/lib/lxc/ubuntu-cn01/fstab

start the container.

error

root@ubuntu:~# lxc-start -n ubuntu-cn01 -d

lxc-start: lxc_start.c: main: 342 The container failed to start.

lxc-start: lxc_start.c: main: 344 To get more details, run the container in foreground mode.

lxc-start: lxc_start.c: main: 346 Additional information can be obtained by setting the --logfile and --logpriority options.

start the container again with logfile option.

root@ubuntu:~# lxc-start -n ubuntu-cn01 -d --logfile log_ubuntu-cn01

lxc-start: lxc_start.c: main: 342 The container failed to start.

lxc-start: lxc_start.c: main: 344 To get more details, run the container in foreground mode.

lxc-start: lxc_start.c: main: 346 Additional information can be obtained by setting the --logfile and --logpriority options.

check the log file.

There is no mnt/sdb3 directory in the container.

root@ubuntu:~# cat log_ubuntu-cn01

     lxc-start 1446740734.065 ERROR    lxc_utils - utils.c:safe_mount:1434 - No such file or directory - Mount of '/dev/sdb3' onto '/usr/lib/x86_64-linux-gnu/lxc/mnt/sdb3' failed

     lxc-start 1446740734.065 ERROR    lxc_conf - conf.c:mount_entry:2051 - No such file or directory - failed to mount '/dev/sdb3' on '/usr/lib/x86_64-linux-gnu/lxc/mnt/sdb3'

     lxc-start 1446740734.065 ERROR    lxc_conf - conf.c:lxc_setup:4160 - failed to setup the mounts for 'ubuntu-cn01'

create a direcotry.

root@ubuntu:~# mkdir /var/lib/lxc/ubuntu-cn01/rootfs/mnt/sdb3

start the container

root@ubuntu:~# lxc-start -n ubuntu-cn01 -d

I was able to see a mount point in the container.

root@ubuntu-cn01:~# ls /mnt/sdb3/

hello.txt  lost+found

[ device option ]

check the major/minor of /des/sdb3 on the LXC host

root@ubuntu:~# sudo ls -l /dev/sdb3

brw-rw---- 1 root disk 8, 19 11月  5 21:38 /dev/sdb3

create a block device for the container.

root@ubuntu:~# mknod /var/lib/lxc/ubuntu-cn01/rootfs/dev/sdb3 b 8 19

edit config file of the container.

root@ubuntu:~# tail -2 /var/lib/lxc/ubuntu-cn01/config

lxc.cgroup.devices.allow = b 8:19 rwm

lxc.mount.entry = /dev/sdb3 /var/lib/lxc/ubuntu-cn01/rootfs/dev/sdb3 none bind 0 0

start the container.

root@ubuntu:~# lxc-start -n ubuntu-cn01 -d

on the container

root@ubuntu-cn01:~# mount | grep sdb3

udev on /dev/sdb3 type devtmpfs (rw,relatime,size=8040160k,nr_inodes=2010040,mode=755)

mount /dev/sdb3.

root@ubuntu-cn01:~# mount -t ext4 /dev/sdb3  tmp_dir1

root@ubuntu-cn01:~#

root@ubuntu-cn01:~# mount | grep sdb3

udev on /dev/sdb3 type devtmpfs (rw,relatime,size=8040160k,nr_inodes=2010040,mode=755)

/dev/sdb3 on /root/tmp_dir1 type ext4 (rw)

root@ubuntu-cn01:~#

root@ubuntu-cn01:~# ls -l tmp_dir1/

合計 16

-rw-r--r-- 1 root root     0 11月  6 01:08 hello.txt

drwx------ 2 root root 16384 11月  5 01:25 lost+found