042、用volume container 共享数据 （2019-03-05 周二）

参考https://www.cnblogs.com/CloudMan6/p/7188479.html

 

volume container 是专门为其他容器提供 volume 的容器，他提供的卷也可以是bind mount ，也可以是docker managed volume

 

创建容器vc_data，因为它只负责提供数据，无需运行，docker create即可。

容器mount了两个volume，bind mount用来存放webserver的静态文件，docker managed volume用来存放一些实用工具

 

[root@docker-lab ~]# cat ~/htdocs/index.html

This a test HTML file

[root@docker-lab ~]# docker create --name vc_data -v ~/htdocs:/usr/local/apache2/htdocs -v /other/useful/tools busybox

6c12ead74cd754c2da6e0e801b798a93d38965d84fc2eea9c120bcf627e99560

[root@docker-lab ~]# docker inspect vc_data

 

        "Mounts": [

            {

                "Type": "bind",

                "Source": "/root/htdocs",

                "Destination": "/usr/local/apache2/htdocs",

                "Mode": "",

                "RW": true,

                "Propagation": "rprivate"

            },

            {

                "Type": "volume",

                "Name": "14ae5efb5762a333bcceb26503ca974122d67cf31ed68da1b22773065b6fa696",

                "Source": "/var/lib/docker/volumes/14ae5efb5762a333bcceb26503ca974122d67cf31ed68da1b22773065b6fa696/_data",

                "Destination": "/other/useful/tools",

                "Driver": "local",

                "Mode": "",

                "RW": true,

                "Propagation": ""

            }

        ]

 

其他容器可以使用 --volumes-from 使用vc_data 这个volume container

 

[root@docker-lab ~]# docker run --name web01 -d -p 80 --volumes-from vc_data httpd

90feafa492fe582ba97072e660a5661587b14bd40de60d6b78d14a3127294328

[root@docker-lab ~]# docker run --name web02 -d -p 80 --volumes-from vc_data httpd

a04615d5f438bc609ce35e04c2a3d76bb6df78e627d4136cf56e83b18d794517

[root@docker-lab ~]# docker run --name web03 -d -p 80 --volumes-from vc_data httpd

88613c4f0e6cd112a359bf68dfe515e7469883ea76f2df85f37c022f84e5fd63

 

[root@docker-lab ~]# docker ps

CONTAINER ID        IMAGE               COMMAND              CREATED             STATUS              PORTS                   NAMES

88613c4f0e6c        httpd               "httpd-foreground"   3 seconds ago       Up 2 seconds        0.0.0.0:32770->80/tcp   web03

a04615d5f438        httpd               "httpd-foreground"   8 seconds ago       Up 7 seconds        0.0.0.0:32769->80/tcp   web02

90feafa492fe        httpd               "httpd-foreground"   13 seconds ago      Up 12 seconds       0.0.0.0:32768->80/tcp   web01

 

[root@docker-lab ~]# docker inspect web01 -f '{{.NetworkSettings.IPAddress}}'

172.17.0.2

[root@docker-lab ~]# docker inspect web02 -f '{{.NetworkSettings.IPAddress}}'

172.17.0.3

[root@docker-lab ~]# docker inspect web03 -f '{{.NetworkSettings.IPAddress}}'

172.17.0.4

 

[root@docker-lab ~]# curl http://127.0.0.1:32768

This a test HTML file

[root@docker-lab ~]# curl http://127.0.0.1:32769

This a test HTML file

[root@docker-lab ~]# curl http://127.0.0.1:32770

This a test HTML file

 

[root@docker-lab ~]# docker inspect vc_data -f '{{.Mounts}}'

[

    {bind  /root/htdocs /usr/local/apache2/htdocs   true rprivate} 

    {volume 14ae5efb5762a333bcceb26503ca974122d67cf31ed68da1b22773065b6fa696 /var/lib/docker/volumes/14ae5efb5762a333bcceb26503ca974122d67cf31ed68da1b22773065b6fa696/_data /other/useful/tools local  true }

]

[root@docker-lab ~]# docker inspect web01 -f '{{.Mounts}}'

[

    {bind  /root/htdocs /usr/local/apache2/htdocs   true rprivate} 

    {volume 14ae5efb5762a333bcceb26503ca974122d67cf31ed68da1b22773065b6fa696 /var/lib/docker/volumes/14ae5efb5762a333bcceb26503ca974122d67cf31ed68da1b22773065b6fa696/_data /other/useful/tools local  true }

]

[root@docker-lab ~]# docker inspect web02 -f '{{.Mounts}}'

[

    {bind  /root/htdocs /usr/local/apache2/htdocs   true rprivate} 

    {volume 14ae5efb5762a333bcceb26503ca974122d67cf31ed68da1b22773065b6fa696 /var/lib/docker/volumes/14ae5efb5762a333bcceb26503ca974122d67cf31ed68da1b22773065b6fa696/_data /other/useful/tools local  true }

]

[root@docker-lab ~]# docker inspect web03 -f '{{.Mounts}}'

[

    {bind  /root/htdocs /usr/local/apache2/htdocs   true rprivate} 

    {volume 14ae5efb5762a333bcceb26503ca974122d67cf31ed68da1b22773065b6fa696 /var/lib/docker/volumes/14ae5efb5762a333bcceb26503ca974122d67cf31ed68da1b22773065b6fa696/_data /other/useful/tools local  true }

]

 

上面可以看到三个web容器都成功的共享了 volume container 中的volume。

 

volume container 特点：

 

1、与bind mount 相比，不必为每一个容器指定host path，所有path都在volume container的容器中定义，容器只需要与volume container关联，实现了容器与host的解耦

 

2、使用volume container 的容器其mount point是一致的，有利于配置和的规范和标准化，也带来一定的局限性，使用时需要综合考虑