docker数据卷：数据卷管理和convoy卷插件

一、 docker数据卷管理

1. 为什么要用数据卷

2. docker提供两种卷

[[e-mail] ~]# docker network prune 将不用的网络清除掉
[[e-mail] ~]# docker run -d --name vm1 -v /opt/website:/usr/share/nginx/html nginx
56cb4e323a20c34dbd36b23d73647e7f83324f5bad83752796e6c91e724f0cf9

[[e-mail] website]# curl 172.17.0.2
/opt/website

[[e-mail] docker]# docker run -d --name registry registry
fc4dd2676bc25ad2db56daf04b867f332383295ec3cc82cd84dd65d5f2cd1d2f

[[e-mail] volumes]# ls
b3d8a5831c678f8bd94d72f59ed76adb41c3f7c701e8767cb1a890ae66ef7986  metadata.db

通过docker volume可以将容器内的内容复制到挂载点
[[e-mail] _data]# docker run -d --name vm2 -v /usr/share/nginx/html nginx
e6941d7e4ec13979bb10a62a31c707bed2f981d51f99cabf370fc772259c6fa3
[[e-mail] 3117caa56a6c78ac79f7b94ed441ce19d08b5ffd69cd0bd22ef1189b017c3eae]# cd _data/
[[e-mail] _data]# ls
50x.html  index.html

3. bind mount 和docker managed volume对比

相同点：两者都是host文件系统中的某个路径

不同点：

二、卷插件简介

三、convoy卷插件

1. 支持三种运行方式：devicemapper，NFS，EBS。

以下实验使用nfs的方式。
下载软件：
https://github.com/rancher/convoy/releases/download/v0.5.0/convoy.tar.gz
在所有节点提前挂载NFS存储

2. convoy卷插件安装

[[e-mail] ~]# yum install -y nfs-utils
[[e-mail] ~]# yum install -y nfs-utils

[[e-mail] ~]# systemctl start rpcbind
[[e-mail] ~]# systemctl start rpcbind

同步nfs
[[e-mail] ~]# cat /etc/exports
/nfs 	*(rw)
[[e-mail] ~]# systemctl start nfs
[[e-mail] ~]# showmount -e
Export list for server1:
/nfs *
[[e-mail] /]# mkdir /nfs

[[e-mail] ~]# mkdir /nfs
[[e-mail] ~]# showmount -e server1
Export list for server1:
/nfs *
[[e-mail] ~]# mount 172.25.60.1:/nfs/ /nfs/
[[e-mail] ~]# df
Filesystem            1K-blocks    Used Available Use% Mounted on
172.25.60.1:/nfs       17811456 2572160  15239296  15% /nfs

[[e-mail] /]# cat /etc/exports  因为server2使用的时nfsnobody的身份，无法操作nfs挂载目录中的数据，所以将其改为no_root_squash
/nfs 	*(rw,no_root_squash)  
[[e-mail] /]# exportfs -rv
exporting *:/nfs

server2可以读写nfs挂载点
[[e-mail] /]# cd /nfs/
[[e-mail] nfs]# echo hello > test
[[e-mail] ~]# cd /nfs/
[[e-mail] nfs]# ls
test
[[e-mail] nfs]# rm -fr test

docker通过卷插件（plugins）访问nfs
[[e-mail] ~]# tar zxf convoy.tar.gz 
[[e-mail] ~]# cd convoy/
[[e-mail] convoy]# ls
convoy  convoy-pdata_tools  SHA1SUMS
[[e-mail] convoy]# mv * /usr/local/bin/
[[e-mail] ~]# which convoy
/usr/local/bin/convoy

[[e-mail] ~]# tar -vzxf convoy.tar.gz 
convoy/
convoy/convoy-pdata_tools
convoy/convoy
convoy/SHA1SUMS
[[e-mail] ~]# cd convoy/
[[e-mail] convoy]# mv * /usr/local/bin/
[[e-mail] convoy]# which convoy
/usr/local/bin/convoy
[[e-mail] ~]# mkdir -p /etc/docker/plugins/  
/etc/docker时docker缺省的一个扫描路径
[[e-mail] convoy]# mkdir -p /etc/docker/plugins/

将convoy打入后台
[[e-mail] ~]# convoy daemon --drivers vfs --driver-opts vfs.path=/nfs &

[[e-mail] nfs]# ll /run/convoy/convoy.sock 
srwxr-xr-x 1 root root 0 Apr  9 22:21 /run/convoy/convoy.sock

[[e-mail] nfs]# echo "unix:///var/run/convoy/convoy.sock" > /etc/docker/plugins/convoy.spec

[[e-mail] convoy]# convoy daemon --drivers vfs --driver-opts vfs.path=/nfs &
[[e-mail] convoy]# ll /run/convoy/convoy.sock
srwxr-xr-x 1 root root 0 Apr  9 22:26 /run/convoy/convoy.sock
[[e-mail] convoy]# echo "unix:///var/run/convoy/convoy.sock" > /etc/docker/plugins/convoy.spec

创建卷
[[e-mail] nfs]# convoy create vol1
[[e-mail] nfs]# ls
config  vol1

[[e-mail] nfs]# convoy list
{
	"vol1": {
		"Name": "vol1",
		"Driver": "vfs",
		"MountPoint": "",
		"CreatedTime": "Thu Apr 09 22:29:04 +0800 2020",
		"DriverInfo": {
			"Driver": "vfs",
			"MountPoint": "",
			"Path": "/nfs/vol1",
			"PrepareForVM": "false",
			"Size": "0",
			"VolumeCreatedAt": "Thu Apr 09 22:29:04 +0800 2020",
			"VolumeName": "vol1"
		},
		"Snapshots": {}
	}
}

[[e-mail] nfs]# docker run -d --name vm1 -v vol1:/usr/share/nginx/html nginx
[[e-mail] nfs]# ls vol1/
50x.html  index.html

[[e-mail] ~]# ls /nfs/vol1/
50x.html  index.html

容器可以销毁但是原来的数据保存在nfx中
[[e-mail] nfs]# docker rm -f vm1
[[e-mail] nfs]# ls vol1/
50x.html  index.html

数据同步过程：

docker engine --- /etc/docker/plugins/convoy.spec --- /run/convoy/convoy.sock ---api ---vol1 --- server2(同步到其它的节点)

删除卷
[[e-mail] ~]# convoy delete vol1

[[e-mail] ~]# mv /etc/docker/plugins/convoy.spec /mnt/ 或者直接删掉plugins

kill (convoy服务)
[[e-mail] docker]# systemctl daemon-reload 
[[e-mail] ~]# systemctl restart docker

docker默认创建的volume在/var/lib/docker/volumes/中
[[e-mail] ~]# docker volume create vol1
vol1
[[e-mail] ~]# ls /var/lib/docker/volumes/
metadata.db  vol1