CentOS 7.x 上面的 LXC 測試環境 (4) - 將 Host 目錄同時掛載到多個 LXC Container 中

LXC 可以讓不同 Container 之間都可以共同存取，用來假裝 NFS 目錄，作一些情境演練。例如，PostgreSQL 的 HA 設置中，需要共用目錄存放 WAL 備份。

當然，直接讓某個 Container 設置 NFS 讓其他 Container 存取也是完全 OK 的～

這邊示範，把外部的 /media/share/ 目錄，掛載到兩個 container 裡面的 /mount/share/ 目錄下。主要是設定 Container 外部的 Config 檔案就可以了

[user@lxc-lab ~]$ sudo mkdir -p /media/share/
[user@lxc-lab ~]$ sudo chmod 777 /media/share/
[user@lxc-lab ~]$ sudo mkdir -p /var/lib/lxc/container1/rootfs/mount/share/ /var/lib/lxc/container2/rootfs/mount/share/
[user@lxc-lab ~]$ 
[user@lxc-lab ~]$ sudo tee -a /var/lib/lxc/container1/config << EOF 
# Mounting external Directory in R/W mode
lxc.mount.entry = /media/share/ mount/share/ none bind 0.0
EOF
[user@lxc-lab ~]$ sudo tee -a /var/lib/lxc/container2/config << EOF 
# Mounting external Directory in R/W mode
lxc.mount.entry = /media/share/ mount/share/ none bind 0.0
EOF
[user@lxc-lab ~]$ 

然後啟動兩個 Container，進去 container1 產生一個空檔案，再到 container2 寫看看，再回 container1 確認一下

[user@lxc-lab ~]$ sudo ./startenv.sh container1 container2
Starting container environment container1
Starting container environment container2
[user@lxc-lab ~]$ sudo ./envlogin.sh container1

Connected to tty 0
                  Type  to exit the console,  to enter Ctrl+a itself

CentOS Linux 7 (Core)
Kernel 3.10.0-957.1.3.el7.x86_64 on an x86_64

container1 login: root
Password: 
Last login: Sun Jan 27 13:55:45 on lxc/console
[root@container1 ~]# 
[root@container1 ~]# touch /mount/share/container1file
[root@container1 ~]# exit
logout

CentOS Linux 7 (Core)
Kernel 3.10.0-957.1.3.el7.x86_64 on an x86_64

container1 login: [user@lxc-lab ~]$ 
[user@lxc-lab ~]$ 

[brandon_hsu@lxc-lab ~]$ sudo ./envlogin.sh container2

Connected to tty 0
                  Type  to exit the console,  to enter Ctrl+a itself

CentOS Linux 7 (Core)
Kernel 3.10.0-957.1.3.el7.x86_64 on an x86_64

container2 login: root
Password: 
[root@container2 ~]# ls /mount/share/
container1file
[root@container2 ~]#
[root@container2 ~]# echo 'Write by container2' >> /mount/share/container1file 
[root@container2 ~]# exit
logout

CentOS Linux 7 (Core)
Kernel 3.10.0-957.1.3.el7.x86_64 on an x86_64

container2 login: [brandon_hsu@lxc-lab ~]$ 
[brandon_hsu@lxc-lab ~]$ 

[brandon_hsu@lxc-lab ~]$ sudo ./envlogin.sh container1

Connected to tty 0
                  Type  to exit the console,  to enter Ctrl+a itself

CentOS Linux 7 (Core)
Kernel 3.10.0-957.1.3.el7.x86_64 on an x86_64

container1 login: root
Password: 
Last login: Sun Jan 27 13:56:07 on lxc/console
[root@container1 ~]# cat /mount/share/container1file 
Write by container2
[root@container1 ~]# 

這樣就是掛載成功了，兩個 Container 可以同時讀寫這個目錄的內容了