docker使用nfs 做跨主机存储

构建容错应用程序时，可能需要配置同一服务的多个副本才能访问相同的文件。

There are several ways to achieve this when developing your applications. One is to add logic to your application to store files on a cloud object storage system like Amazon S3. Another is to create volumes with a driver that supports writing files to an external storage system like NFS or Amazon S3.

Volume drivers allow you to abstract the underlying storage system from the application logic. For example, if your services use a volume with an NFS driver, you can update the services to use a different driver, as an example to store data in the cloud, without changing the application logic.

安装nfs

[root@bogon ~]# yum install nfs-utils rpcbind -y
[root@bogon ~]# mkdir -p /data/nfs/docker
[root@bogon ~]# echo "/data/nfs *(rw,no_root_squash,sync)">>/etc/exports
[root@bogon ~]# exportfs -r
[root@bogon ~]# systemctl start rpcbind nfs-server
[root@bogon ~]# systemctl enable rpcbind nfs-server
Created symlink from /etc/systemd/system/multi-user.target.wants/nfs-server.service to /usr/lib/systemd/system/nfs-server.service.
[root@bogon ~]# showmount -e localhost
Export list for localhost:
/data/nfs *

docker节点需要安装nfs 客户端

root@playbook-master:~# sudo apt install nfs-common

root@playbook-master:~# showmount -e 192.168.138.130
Export list for 192.168.138.130:
/data/nfs *

root@playbook-master:~# docker volume create --driver local --opt type=nfs --opt o=addr=192.168.138.130,rw --opt device=:/data/nfs volume-nfs
volume-nfs

root@playbook-master:~# docker volume inspect volume-nfs
[
{
"CreatedAt": "2018-12-20T12:09:03+08:00",
"Driver": "local",
"Labels": {},
"Mountpoint": "/var/lib/docker/volumes/volume-nfs/_data",
"Name": "volume-nfs",
"Options": {
"device": ":/data/nfs",
"o": "addr=192.168.138.130,rw",
"type": "nfs"
},
"Scope": "local"
}
]

root@playbook-master:~# sudo apt install nfs-common

root@playbook-master:~# showmount -e 192.168.138.130
Export list for 192.168.138.130:
/data/nfs *

root@playbook-master:~# docker volume create --driver local --opt type=nfs --opt o=addr=192.168.138.130,rw --opt device=:/data/nfs volume-nfs
volume-nfs

root@playbook-master:~# docker volume inspect volume-nfs
[
{
"CreatedAt": "2018-12-20T12:09:03+08:00",
"Driver": "local",
"Labels": {},
"Mountpoint": "/var/lib/docker/volumes/volume-nfs/_data",
"Name": "volume-nfs",
"Options": {
"device": ":/data/nfs",
"o": "addr=192.168.138.130,rw",
"type": "nfs"
},
"Scope": "local"
}
]

测试docker 在一台宕机或删除，重启一个容器或在另一台重启一个查看数据情况；

root@playbook-master:~# docker run -dit --name data1 -v volume-nfs:/mnt ubuntu:16.04 
05d6e8cb75dc99a71f11c6c2a0833369b40be7dc9f650c814b403d519b11d50d
root@playbook-master:~# docker ps
CONTAINER ID        IMAGE               COMMAND             CREATED             STATUS              PORTS               NAMES
05d6e8cb75dc        ubuntu:16.04        "/bin/bash"         3 seconds ago       Up 1 second                             data1
root@playbook-master:~# docker exec data1 ls /mnt
docker
houpj.txt
删除容器在另一台节点
root@ubuntu:~# docker run -dit --name data2 -v volume-nfs:/mnt ubuntu:16.04 
b8fff79ccaeaeac97161bb14d69d4ae6ea21ce00ae9c95ecd476dcfe2640b08f
root@ubuntu:~# docker ps
CONTAINER ID        IMAGE               COMMAND             CREATED             STATUS              PORTS               NAMES
b8fff79ccaea        ubuntu:16.04        "/bin/bash"         4 seconds ago       Up 3 seconds                            data2
c3e3c995acac        busybox             "sh"                12 minutes ago      Up 12 minutes                           busybox7
root@ubuntu:~# docker exec -it data2 /bin/bash
root@b8fff79ccaea:/# ls
bin  boot  dev  etc  home  lib  lib64  media  mnt  opt  proc  root  run  sbin  srv  sys  tmp  usr  var
root@b8fff79ccaea:/# ls /mnt/
docker  houpj.txt

参考：

https://www.cnblogs.com/elvi/p/8463673.html 

https://forums.docker.com/t/docker-volume-create/41160