首页手记 docker高级应用之动态绑定卷组

docker高级应用之动态绑定卷组

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Docker

之前介绍过docker高级应用之动态扩展容器空间大小（地址：http://dl528888.blog.51cto.com/2382721/1606170），本次介绍如何动态的绑定卷组。

为什么使用卷组呢，比如想把物理机里的目录给予容器共享，或者把物理机的一个目录作为共享目录，做日志搜集等等功能。

默认docker添加卷组是在启动容器的使用使用-v参数

-v, --volume=[] Bind mount a volume (e.g., from the host: -v /host:/container, from docker: -v /container)

举例

物理机目录/data/software想挂载到容器的/tmp/software里

其中/data/software内容是

15:21:14 # ll /data/software/

total 19692

-rw-r--r-- 1 root root 1940 Nov 10 20:42 CentOS-Base-6.repo

-rwxr-xr-x 1 root root 12752168 Nov 10 14:15 etcd

-rwxr-xr-x 1 root root 7400424 Nov 10 14:15 etcdctl

drwxr-xr-x 21 1000 1000 4096 Oct 29 02:06 systemd-217

启动docker的命令是

docker run -d -p 22 --name="test" -v /data/software:/tmp/software docker.ops-chukong.com:5000/centos6-http:new /usr/bin/supervisord

下面是做绑定测试

root@docker-test2:/tmp

15:29:23 # docker run -d -p 22 --name="test" -v /data/software:/tmp/software docker.ops-chukong.com:5000/centos6-http:new /usr/bin/supervisord

a21506d7b36e04e091008f4a326ac17c94e3d855e3aadb52992d7ba95f45cbbf

root@docker-test2:/tmp

15:31:15 # docker-enter test sh -c "ls -l /tmp/software"

total 19692

-rw-r--r-- 1 root root 1940 Nov 10 20:42 CentOS-Base-6.repo

-rwxr-xr-x 1 root root 12752168 Nov 10 14:15 etcd

-rwxr-xr-x 1 root root 7400424 Nov 10 14:15 etcdctl

drwxr-xr-x 21 1000 1000 4096 Oct 29 02:06 systemd-217

root@docker-test2:/tmp

15:31:21 # docker-enter test sh -c "mount"

rootfs on / type rootfs (rw)

/dev/mapper/docker-8:17-37748738-a21506d7b36e04e091008f4a326ac17c94e3d855e3aadb52992d7ba95f45cbbf on / type ext4 (rw,relatime,discard,stripe=16,data=ordered)

proc on /proc type proc (rw,nosuid,nodev,noexec,relatime)

sysfs on /sys type sysfs (rw,nosuid,nodev,noexec,relatime)

shm on /dev/shm type tmpfs (rw,nosuid,nodev,noexec,relatime,size=65536k)

/dev/sdb1 on /.dockerinit type ext4 (rw,relatime,data=ordered)

/dev/sda3 on /etc/resolv.conf type ext4 (rw,relatime,data=ordered)

/dev/sdb1 on /etc/hostname type ext4 (rw,relatime,data=ordered)

/dev/sdb1 on /etc/hosts type ext4 (rw,relatime,data=ordered)

/dev/sda3 on /tmp/software type ext4 (rw,relatime,data=ordered)

/dev/sdb1 on /.dockerenv type ext4 (rw,relatime,data=ordered)

devpts on /dev/tty1 type devpts (rw,relatime,gid=5,mode=620,ptmxmode=000)

devpts on /dev/pts type devpts (rw,relatime,gid=5,mode=620,ptmxmode=666)

devpts on /dev/ptmx type devpts (rw,relatime,gid=5,mode=620,ptmxmode=666)

root@docker-test2:/tmp

15:31:28 # docker-enter test sh -c "df -h"

Filesystem Size Used Avail Use% Mounted on

rootfs 9.8G 470M 8.8G 5% /

/dev/mapper/docker-8:17-37748738-a21506d7b36e04e091008f4a326ac17c94e3d855e3aadb52992d7ba95f45cbbf

9.8G 470M 8.8G 5% /

shm 64M 0 64M 0% /dev/shm

/dev/sdb1 1.8T 22G 1.7T 2% /.dockerinit

/dev/sda3 518G 457G 35G 93% /etc/resolv.conf

/dev/sdb1 1.8T 22G 1.7T 2% /etc/hostname

/dev/sdb1 1.8T 22G 1.7T 2% /etc/hosts

/dev/sda3 518G 457G 35G 93% /tmp/software

/dev/sdb1 1.8T 22G 1.7T 2% /.dockerenv

可以看到挂载完成，并且容器里的/tmp/software与/data/software里内容一致

但上面只是在创建并启动容器的时候可以挂载卷组，如果允许中的如何挂载呢？

具体知识可以参考http://jpetazzo.github.io/2015/01/13/docker-mount-dynamic-volumes/

下面是修改的脚本

内容为

#!/bin/bash

#This script is dynamic mount docker volumens

#Author Deng Lei

if [ -z $1 ] || [ -z $2 ] || [ -z $3 ]; then

echo "Usage: container_name physics_volumes container_volumes"

echo "Example: I want mount physics /tmp/test to container /src in test"

echo "The command is: bash `basename $0` test /tmp/test /src "

exit 1

which nsenter &>>/dev/null

if [ $? -ne 0 ];then

echo "plsease install nsenser,command is:yum install util-linux"

exit 1

set -e

CONTAINER=$1

HOSTPATH=$2

CONTPATH=$3

if [ ! -d $HOSTPATH ];then

echo "physics $HOSTPATH is not exist!"

exit 1

REALPATH=$(readlink --canonicalize $HOSTPATH)

FILESYS=$(df -P $REALPATH | tail -n 1 | awk '{print $6}')

while read DEV MOUNT JUNK

[ $MOUNT = $FILESYS ] && [ $DEV != "rootfs" ] && break

done </proc/mounts

[ $MOUNT = $FILESYS ] # Sanity check!

while read A B C SUBROOT MOUNT JUNK

do [ $MOUNT = $FILESYS ] && break

done < /proc/self/mountinfo

[ $MOUNT = $FILESYS ] # Moar sanity check!

SUBPATH=$(echo $REALPATH | sed s,^$FILESYS,,)

DEVDEC=$(printf "%d %d" $(stat --format "0x%t 0x%T" $DEV))

PID=$(docker inspect --format "``.`State`.`Pid`" "$CONTAINER")

run_command="nsenter --target $PID --mount --uts --ipc --net --pid -- sh -c"

if [ `$run_command "mount|grep $CONTPATH|wc -l"` -ne 0 ];then

echo "container $CONTAINER mount dir $CONTPATH is mounting!"

exit 1

$run_command "[ -b $DEV ] ||mknod --mode 0600 $DEV b $DEVDEC"

$run_command "mkdir /tmpmnt"

$run_command "mount $DEV /tmpmnt"

$run_command "mkdir -p $CONTPATH"

$run_command "mount -o bind /tmpmnt/$SUBROOT/$SUBPATH $CONTPATH"

$run_command "umount /tmpmnt"

$run_command "rmdir /tmpmnt"

check_result=`$run_command "mount|grep $CONTPATH|wc -l"`

if [ $check_result -ne 0 ];then

echo "dymainc mount physics $HOSTPATH on $CONTAINER $CONTPATH is success!"

else

echo "dymaninc mount physics $HOSTPATH on $CONTAINER $CONTPATH is fail!"

然后在给已经存在的test容器里新挂载一个卷组，把本地的/data/docker-dir挂载到/tmp/docker-dir

当前物理机/data/docker-dir里内容是

root@docker-test2:/tmp

15:37:17 # ll /data/docker-dir/

total 4

-rw-r--r-- 1 root root 0 Feb 11 09:31 a

-rw-r--r-- 1 root root 2 Feb 11 09:31 b

挂载的方法是

15:38:28 # sh dynamic_mount_docker_volume.sh

Usage: container_name physics_volumes container_volumes

Example: I want mount physics /tmp/test to container /src in test

The command is: bash dynamic_mount_docker_volume.sh test /tmp/test /src

第一个参数是容器名，第二个参数的物理机的目录，第三个参数是挂载到容器里的目录

进行挂载

root@docker-test2:/tmp

15:36:14 # sh dynamic_mount_docker_volume.sh test /data/docker-dir/ /tmp/docker-dir

dymainc mount physics /data/docker-dir/ on test /tmp/docker-dir is success!

可以看到成功的挂载了

下面做一下测试

15:37:28 # docker-enter test sh -c "ls -l /tmp/docker-dir"

total 4

-rw-r--r-- 1 root root 0 Feb 11 09:31 a

-rw-r--r-- 1 root root 2 Feb 11 09:31 b

root@docker-test2:/tmp

15:38:18 # docker-enter test sh -c "mount"