docker 容器数据卷
是什么
Docker的理念：将运用与运行的环境打包形成容器运行 ，运行可以伴随着容器，但是我们对数据的要求希望是持久化的，容器之间希望有可能共享数据
Docker容器产生的数据，如果不通过docker commit生成新的镜像，使得数据做为镜像的一部分保存下来，那么当容器删除后，数据自然也就没有了。
为了能保存数据在docker中我们使用卷
一句话：有点类似我们Redis里面的rdb和aof文件
能干嘛
卷就是目录或文件，存在于一个或多个容器中，由docker挂载到容器，但不属于联合文件系统，因此能够绕过Union File System提供一些用于持续存储或共享数据的特性
卷的设计目的就是数据的持久化，完全独立于容器的生存周期，因此Docker不会在容器删除时删除其挂载的数据卷
特点：
1：数据卷可在容器之间共享或重用数据
2：卷中的更改可以直接生效
3：数据卷中的更改不会包含在镜像的更新中
4：数据卷的生命周期一直持续到没有容器使用它为止
数据卷
直接命令添加
docker run -it -v /宿主机绝对路径目录:/容器内目录 镜像名
查看数据卷是否挂载成功
docker inspect 容器ID
命令(带权限)
只读read only
docker run -it -v /宿主机绝对路径目录:/容器内目录:ro 镜像名
DockerFile添加
可在Dockerfile中使用VOLUME指令来给镜像添加一个或多个数据卷
VOLUME ["/dataVolumeContainer","/dataVolumeContainer2","/dataVolumeContainer3"]
说明：
出于可移植和分享的考虑，用-v 主机目录:容器目录这种方法不能够直接在Dockerfile中实现。
由于宿主机目录是依赖于特定宿主机的，并不能够保证在所有的宿主机上都存在这样的特定目录。
File构建
# volume test
FROM centos
VOLUME ["/dataVolumeContainer1","/dataVolumeContainer2"]
CMD echo "finished,--------success1"
CMD /bin/bash
build后 生成镜像
docker build -f 本地dockerfile文件 -t 镜像的名字 .
[root@localhost ~]# docker build -f /mydocker/dockerfile01 -t luke2/centos .
Sending build context to Docker daemon 411.5MB
Step 1/4 : FROM centos
---> 0f3e07c0138f
Step 2/4 : VOLUME ["/dataVolumeContainer1","/dataVolumeContainer2"]
---> Using cache
---> 6627b998f4eb
Step 3/4 : CMD echo "finished,--------success1"
---> Using cache
---> dbdde095deeb
Step 4/4 : CMD /bin/bash
---> Using cache
---> 5743072abd8f
Successfully built 5743072abd8f
Successfully tagged luke2/centos:latest
[root@localhost ~]# docker images
REPOSITORY TAG IMAGE ID CREATED SIZE
luke/centos latest 5743072abd8f About an hour ago 220MB
luke2/centos latest 5743072abd8f About an hour ago 220MB
luke/mytomcat 2.0 ec4a01b95ae1 39 hours ago 507MB
mongo latest a0e2e64ac939 6 days ago 364MB
tomcat latest 6fa48e047721 12 days ago 507MB
centos latest 0f3e07c0138f 2 months ago 220MB
hello-world latest fce289e99eb9 11 months ago 1.84kB
run容器
[root@localhost ~]# docker run -it 5743072abd8f /bin/bash
[root@78f5f0978152 /]# ls -l
total 0
lrwxrwxrwx. 1 root root 7 May 11 2019 bin -> usr/bin
drwxr-xr-x. 2 root root 6 Dec 26 02:38 dataVolumeContainer1
drwxr-xr-x. 2 root root 6 Dec 26 02:38 dataVolumeContainer2
drwxr-xr-x. 5 root root 360 Dec 26 02:38 dev
...
通过上述步骤，容器内的卷目录地址已经知道 对应的主机目录地址哪？？
[root@localhost /]# docker inspect 78f5f0978152
[
{
"Id": "78f5f0978152b7a22fd9ad20d215dd1957adabaf3c824fb2ae9b1125ec5c67ae",
"Created": "2019-12-26T02:38:48.726826423Z",
"Path": "/bin/bash",
"Args": [],
...
"Mounts": [
{
"Type": "volume",
"Name": "31bf31f42025668d8e7a535af69375e1535bd626d97201fb690b662b391477d7",
"Source": "/var/lib/docker/volumes/31bf31f42025668d8e7a535af69375e1535bd626d97201fb690b662b391477d7/_data",
"Destination": "/dataVolumeContainer1",
"Driver": "local",
"Mode": "",
"RW": true,
"Propagation": ""
},
{
"Type": "volume",
"Name": "01b64d8c46f70de8487c7e499b101b98dcdbc4091e8491478ecbaca13c099ba3",
"Source": "/var/lib/docker/volumes/01b64d8c46f70de8487c7e499b101b98dcdbc4091e8491478ecbaca13c099ba3/_data",
"Destination": "/dataVolumeContainer2",
"Driver": "local",
"Mode": "",
"RW": true,
"Propagation": ""
}
],
...
]
容器中：
[root@78f5f0978152 /]# cd dataVolumeContainer1
[root@78f5f0978152 dataVolumeContainer1]# touch container.txt
[root@78f5f0978152 dataVolumeContainer1]# vi container.txt
[root@78f5f0978152 dataVolumeContainer1]# cat container.txt
update 01
主机中：
[root@localhost /]# cd /var/lib/docker/volumes/31bf31f42025668d8e7a535af69375e1535bd626d97201fb690b662b391477d7/_data
[root@localhost _data]# ls
container.txt
[root@localhost _data]# cat container.txt
update 01
[root@localhost _data]# vim container.txt
[root@localhost _data]# cat container.txt
update 01
host 02
容器中：
[root@78f5f0978152 dataVolumeContainer1]# cat container.txt
update 01
host 02
备注
Docker挂载主机目录Docker访问出现cannot open directory .: Permission denied
解决办法：在挂载目录后多加一个--privileged=true参数即可
数据卷容器
是什么
命名的容器挂载数据卷，其它容器通过挂载这个(父容器)实现数据共享，挂载数据卷的容器，称之为数据卷容器
容器间传递共享(–volumes-from)
先启动一个父容器dc01
[root@localhost /]# docker ps
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
[root@localhost /]# docker run -it --name dc01 luke/centos
[root@4b656b4809e0 /]# ls -l
total 0
lrwxrwxrwx. 1 root root 7 May 11 2019 bin -> usr/bin
drwxr-xr-x. 2 root root 6 Dec 26 03:44 dataVolumeContainer1
drwxr-xr-x. 2 root root 6 Dec 26 03:44 dataVolumeContainer2
drwxr-xr-x. 5 root root 360 Dec 26 03:44 dev
...
[root@4b656b4809e0 /]# cd dataVolumeContainer2
[root@4b656b4809e0 dataVolumeContainer2]# touch dc01_add.txt
[root@4b656b4809e0 dataVolumeContainer2]#
[root@localhost /]# docker ps
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
4b656b4809e0 luke/centos "/bin/sh -c /bin/bash" 29 seconds ago Up 28 seconds dc01
dc02/dc03继承自dc01
docker run -it --name dc02 --volumes-from dc01 luke/centos
[root@localhost /]# docker run -it --name dc02 --volumes-from dc01 luke/centos
[root@18484790a72a /]# ls -l
total 0
lrwxrwxrwx. 1 root root 7 May 11 2019 bin -> usr/bin
drwxr-xr-x. 2 root root 6 Dec 26 03:44 dataVolumeContainer1
drwxr-xr-x. 2 root root 26 Dec 26 03:44 dataVolumeContainer2
drwxr-xr-x. 5 root root 360 Dec 26 03:49 dev
drwxr-xr-x. 1 root root 66 Dec 26 03:49 etc
...
[root@18484790a72a /]# cd dataVolumeContainer2
[root@18484790a72a dataVolumeContainer2]# ls
dc01_add.txt
[root@18484790a72a dataVolumeContainer2]# touch dc02_add.txt
[root@18484790a72a dataVolumeContainer2]# ls
dc01_add.txt dc02_add.txt
[root@localhost /]# docker ps
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
18484790a72a luke/centos "/bin/sh -c /bin/bash" About a minute ago Up About a minute dc02
4b656b4809e0 luke/centos "/bin/sh -c /bin/bash" 6 minutes ago Up 6 minutes dc01
[root@localhost /]# docker run -it --name dc03 --volumes-from dc01 luke/centos
[root@5a5728c608cf /]# cd /dataVolumeContainer2
[root@5a5728c608cf dataVolumeContainer2]# ls
dc01_add.txt dc02_add.txt
[root@5a5728c608cf dataVolumeContainer2]# touch dc03_add.txt
[root@5a5728c608cf dataVolumeContainer2]#
[root@localhost /]# docker ps
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
5a5728c608cf luke/centos "/bin/sh -c /bin/bash" 39 seconds ago Up 37 seconds dc03
18484790a72a luke/centos "/bin/sh -c /bin/bash" 5 minutes ago Up 5 minutes dc02
4b656b4809e0 luke/centos "/bin/sh -c /bin/bash" 10 minutes ago Up 10 minutes dc01
回到dc01可以看到dc02/dc03各自添加的都能共享了
[root@localhost /]# docker attach dc01
[root@4b656b4809e0 dataVolumeContainer2]# ls -l
total 0
-rw-r--r--. 1 root root 0 Dec 26 03:44 dc01_add.txt
-rw-r--r--. 1 root root 0 Dec 26 03:50 dc02_add.txt
-rw-r--r--. 1 root root 0 Dec 26 03:54 dc03_add.txt
删除dc01，dc02修改后dc03可否访问
[root@localhost /]# docker rm -f dc01
dc01
[root@localhost /]# docker ps
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
5a5728c608cf luke/centos "/bin/sh -c /bin/bash" 4 minutes ago Up 4 minutes dc03
18484790a72a luke/centos "/bin/sh -c /bin/bash" 9 minutes ago Up 9 minutes dc02
[root@localhost /]# docker attach dc02
[root@18484790a72a dataVolumeContainer2]# ls
dc01_add.txt dc02_add.txt dc03_add.txt
[root@18484790a72a dataVolumeContainer2]# touch dc02_update.txt
[root@18484790a72a dataVolumeContainer2]# ls
dc01_add.txt dc02_add.txt dc02_update.txt dc03_add.txt
[root@localhost /]# docker attach dc03
[root@5a5728c608cf dataVolumeContainer2]# ls
dc01_add.txt dc02_add.txt dc02_update.txt dc03_add.txt
结论：容器之间配置信息的传递，数据卷的生命周期一直持续到没有容器使用它为止
来源：CSDN
作者：Luke_9012
链接：https://blog.csdn.net/weixin_42194337/article/details/103856441