将卷挂载到正在运行的容器中（通过！）
参考：
https://medium.com/kokster/mount-volumes-into-a-running-container-65a967bee3b5
https://jpetazzo.github.io/2015/01/13/docker-mount-dynamic-volumes/
把主机上的/home/test 目录挂载到容器的/doot
主机上：
[root@vcapp133 ~]# df /home/test Filesystem 1K-blocks Used Available Use% Mounted on /dev/mapper/centos-root 104806400 86212556 18593844 83% /
[root@vcapp133 test]# less /proc/self/mountinfo
…… 68 1 253:0 / / rw,relatime shared:1 - xfs /dev/mapper/centos-root rw,attr2,inode64,logbufs=8,logbsize=32k,noquota ……
[root@vcapp133 ~]# docker run -dt --name ddd -p 44000:3389 -p 44002:22 --hostname master XXXXX:20220628
[root@vcapp133 ~]# docker exec -it ddd /bin/bash
容器内：
[root@master tmp]# mkdir /dev/mapper
[root@master tmp]# [ -b /dev/mapper/centos-root ] || mknod --mode 0600 /dev/mapper/centos-root b 253 0
[root@master mapper]# mkdir -p /tmpmount
[root@master mapper]# mount /dev/mapper/centos-root /tmpmount mount: permission denied
主机上：
[root@vcapp133 test]# docker inspect --format {{.State.Pid}} 7f704818e3cb 22486
[root@vcapp133 test]# nsenter --target 22486 --mount --uts --ipc --net --pid -- mount /dev/mapper/centos-root /tmpmount
容器内：
[root@master mapper]# ls /tmpmount
bin data etc lib media opt root sbin snap sys usr boot dev home lib64 mnt proc run share srv tmp var
[root@master /]# mkdir /doot
[root@master /]# mount -o bind /tmpmount/home/test /doot mount: permission denied
主机上：
[root@vcapp133 test]# nsenter --target 22486 --mount --uts --ipc --net --pid -- mount -o bind /tmpmount/home/test /doot
容器内：
[root@master tmpmount]# ll /doot/
total 4204 -rwxr-xr-x 1 root root 4302416 Apr 1 2021 cloaker_cli_linux
主机上： [root@vcapp133 test]# nsenter --target 22486 --mount --uts --ipc --net --pid -- umount /tmpmount
[root@vcapp133 test]# nsenter --target 22486 --mount --uts --ipc --net --pid -- rmdir /tmpmount
容器内：
[root@master /]# ll doot/
total 4204 -rwxr-xr-x 1 root root 4302416 Apr 1 2021 cloaker_cli_linux
LCXFS情况下是否仍可动态挂载？
[root@vcapp133 lxcfs-lxcfs-5.0.2]# /usr/bin/lxcfs --version "5.0.2"
[root@vcapp133 lxcfs-lxcfs-5.0.2]# /usr/bin/lxcfs --enable-cfs -l /var/lib/lxc/lxcfs/ ……
[root@vcapp133 ~]# docker run -dt -m 5g --cpu-period=10000 --cpu-quota=20000
-v /sys/fs/cgroup:/sys/fs/cgroup:ro
-v /var/lib/lxc/:/var/lib/lxc/:shared
-v /var/lib/lxc/lxcfs/proc/diskstats:/proc/diskstats:rw,rslave
-v /var/lib/lxc/lxcfs/proc/cpuinfo:/proc/cpuinfo:rw,rslave
-v /var/lib/lxc/lxcfs/proc/meminfo:/proc/meminfo:rw,rslave
-v /var/lib/lxc/lxcfs/proc/stat:/proc/stat:rw,rslave
-v /var/lib/lxc/lxcfs/proc/swaps:/proc/swaps:rw,rslave
-v /var/lib/lxc/lxcfs/proc/uptime:/proc/uptime:rw,rslave
-v /var/lib/lxc/lxcfs/proc/loadavg:/proc/loadavg:rw,rslave
-v /var/lib/lxc/lxcfs/sys/devices/system/cpu/online:/sys/devices/system/cpu/online:ro
--name ddd -p 44000:3389 -p 44002:22 --hostname master
XXXXX:20220628
主机上： [root@vcapp133 ~]# docker inspect --format {{.State.Pid}} 4f42dc3ae70b 27243
[root@vcapp133 ~]# nsenter --target 27243 --mount --uts --ipc --net --pid -- \
mount /dev/mapper/centos-root /tmpmount mount: special device /dev/mapper/centos-root does not exist （失败）
但可以把要挂的目录放到宿主机/var/lib/lxc/下（不要放到/var/lib/lxc/lxcfs下）
注： 将lxcfs目录完全挂载到容器中会造成较大风险，参考 https://www.ai2news.com/blog/1441724/