Docker容器数据卷的基本操作
作者：我可能是个假开发
为了能保存数据在docker中我们使用卷，本文主要介绍了Docker容器数据卷的基本操作，文中通过示例代码介绍的非常详细，对大家的学习或者工作具有一定的参考学习价值，需要的朋友们下面随着小编来一起学习学习吧
一、概念
1.定义
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
2.作用：
- 将运用与运行的环境打包镜像，run后形成容器实例运行 ，但是我们对数据的要求希望是持久化的。
- Docker容器产生的数据，如果不备份，那么当容器实例删除后，容器内的数据自然也就没有了。
- 为了能保存数据在docker中则使用卷。
3.特点：
- 数据卷可在容器之间共享或重用数据
- 卷中的更改可以直接实时生效
- 数据卷中的更改不会包含在镜像的更新中
- 数据卷的生命周期一直持续到没有容器使用它为止
二、添加容器卷
运行一个带有容器卷存储功能的容器实例：docker run -it --privileged=true -v /宿主机绝对路径目录:/容器内目录 镜像名
Docker挂载主机目录访问如果出现cannot open directory .: Permission denied
解决办法：在挂载目录后多加一个--privileged=true参数
1.宿主vs容器之间映射添加容器卷
容器操作：
hongcaixia@hongcaixiadeMacBook-Pro ~ % docker run -it --privileged=true -v /Users/hongcaixia/Documents/host_data:/tmp/docker_data --name=my_centos centos [root@c61d4745b6e8 /]# cd /tmp/docker_data [root@c61d4745b6e8 docker_data]# ls [root@c61d4745b6e8 docker_data]# touch docker.txt [root@c61d4745b6e8 docker_data]# ls docker.txt [root@c61d4745b6e8 docker_data]# ls -- 宿主机在该目录建立了host.txt docker.txt host.txt [root@c61d4745b6e8 docker_data]# echo 'write in docker'>docker.txt [root@c61d4745b6e8 docker_data]# cat docker.txt write in docker [root@c61d4745b6e8 docker_data]# cat docker.txt -- 宿主机在该文件写入了write in host write in docker write in host [root@c61d4745b6e8 docker_data]#
主机操作：
hongcaixia@hongcaixiadeMacBook-Pro ~ % cd /Users/hongcaixia/Documents/host_data hongcaixia@hongcaixiadeMacBook-Pro host_data % ls docker.txt hongcaixia@hongcaixiadeMacBook-Pro host_data % touch host.txt hongcaixia@hongcaixiadeMacBook-Pro host_data % ls docker.txt host.txt hongcaixia@hongcaixiadeMacBook-Pro host_data % vi docker.txt hongcaixia@hongcaixiadeMacBook-Pro host_data % cat docker.txt write in docker write in host hongcaixia@hongcaixiadeMacBook-Pro host_data %
使用docker inspect 容器id 命令查看容器挂载信息：
hongcaixia@hongcaixiadeMacBook-Pro ~ % docker ps
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
dd1b08d9fd2a centos "/bin/bash" 14 minutes ago Up 14 minutes docker_centos
hongcaixia@hongcaixiadeMacBook-Pro ~ % docker inspect dd1b08d9fd2a
[
...
"Mounts": [
{
"Type": "bind",
"Source": "/Users/hongcaixia/Documents/host_data",
"Destination": "/tmp/docker_data",
"Mode": "",
"RW": true,
"Propagation": "rprivate"
}
],
...
]如果容器停止了，主机在挂载目录修改内容，当容器启动之后依旧可以同步到信息：
容器操作：
hongcaixia@hongcaixiadeMacBook-Pro ~ % docker ps CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES dd1b08d9fd2a centos "/bin/bash" 22 minutes ago Up 22 minutes docker_centos hongcaixia@hongcaixiadeMacBook-Pro ~ % docker stop dd1b08d9fd2a dd1b08d9fd2a hongcaixia@hongcaixiadeMacBook-Pro ~ % docker ps CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES hongcaixia@hongcaixiadeMacBook-Pro ~ % docker start dd1b08d9fd2a dd1b08d9fd2a hongcaixia@hongcaixiadeMacBook-Pro ~ % docker ps CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES dd1b08d9fd2a centos "/bin/bash" 24 minutes ago Up 2 seconds docker_centos hongcaixia@hongcaixiadeMacBook-Pro ~ % docker exec -it dd1b08d9fd2a bash [root@dd1b08d9fd2a /]# cd /tmp/docker_data/ [root@dd1b08d9fd2a docker_data]# ls docker.txt docker_in.txt docker_in.txt~ docker_in.txz~ host.txt host1.txt [root@dd1b08d9fd2a docker_data]#
主机操作：在容器停止之后创建host1.txt：
hongcaixia@hongcaixiadeMacBook-Pro host_data % touch host1.txt hongcaixia@hongcaixiadeMacBook-Pro host_data % ls docker.txt docker_in.txt docker_in.txt~ docker_in.txz~ host.txt host1.txt hongcaixia@hongcaixiadeMacBook-Pro host_data %
2.添加读写映射规则
默认是可读可写
设置只读限制：容器实例内部被限制，只能读取不能写 docker run -it --privileged=true -v /宿主机绝对路径目录:/容器内目录:ro 镜像名
容器操作：
hongcaixia@hongcaixiadeMacBook-Pro ~ % docker run -it --privileged=true -v /Users/hongcaixia/Documents/host_data2:/tmp/docker_data2:ro --name=hcx_centos2 centos [root@f12971f08fb1 /]# ls bin dev etc home lib lib64 lost+found media mnt opt proc root run sbin srv sys tmp usr var [root@f12971f08fb1 /]# cd /tmp/docker_data2/ [root@f12971f08fb1 docker_data2]# ls -- 在主机中创建的文件 host.txt [root@f12971f08fb1 docker_data2]# touch docker.txt touch: cannot touch 'docker.txt': Read-only file system [root@f12971f08fb1 docker_data2]#
主机操作：
hongcaixia@hongcaixiadeMacBook-Pro Documents % cd host_data2 hongcaixia@hongcaixiadeMacBook-Pro host_data2 % ls hongcaixia@hongcaixiadeMacBook-Pro host_data2 % touch host.txt hongcaixia@hongcaixiadeMacBook-Pro host_data2 % ls host.txt hongcaixia@hongcaixiadeMacBook-Pro host_data2 %
三、卷的继承和共享
docker run -it --privileged=true --volumes-from 父类 --name 容器名 镜像名
第一个容器my_centos3:
hongcaixia@hongcaixiadeMacBook-Pro ~ % docker run -it --privileged=true -v /Users/hongcaixia/Documents/host_data3:/tmp/docker_data3 --name=my_centos3 centos [root@1e7c088b1b4d /]# cd /tmp/docker_data3 [root@1e7c088b1b4d docker_data3]# ls [root@1e7c088b1b4d docker_data3]# touch docker3.txt [root@1e7c088b1b4d docker_data3]# ls docker3.txt [root@1e7c088b1b4d docker_data3]# ls docker3.txt docker4.txt [root@1e7c088b1b4d docker_data3]# ls docker3.txt docker4.txt host.txt [root@1e7c088b1b4d docker_data3]# -- 停掉父容器，不影响子容器和主机的同步 hongcaixia@hongcaixiadeMacBook-Pro ~ % docker ps CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES 671ef51c2961 centos "/bin/bash" 6 minutes ago Up 6 minutes my_centos4 hongcaixia@hongcaixiadeMacBook-Pro ~ % docker stop 671ef51c2961 671ef51c2961 hongcaixia@hongcaixiadeMacBook-Pro ~ % docker ps CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES hongcaixia@hongcaixiadeMacBook-Pro ~ % -- 父容器恢复，主机和子容器的操作可以同步过来 hongcaixia@hongcaixiadeMacBook-Pro ~ % docker start 671ef51c2961 671ef51c2961 hongcaixia@hongcaixiadeMacBook-Pro ~ % docker exec -it 671ef51c2961 /bin/bash [root@671ef51c2961 /]# cd /tmp/docker_data3/ [root@671ef51c2961 docker_data3]# ls docker3.txt docker4.txt host.txt host2.txt [root@671ef51c2961 docker_data3]#
第二个容器my_centos4: 继承3的容器卷
hongcaixia@hongcaixiadeMacBook-Pro ~ % docker run -it --privileged=true --volumes-from my_centos3 --name=my_centos4 centos [root@671ef51c2961 /]# cd /tmp/docker_data3 [root@671ef51c2961 docker_data3]# ls docker3.txt [root@671ef51c2961 docker_data3]# touch docker4.txt [root@671ef51c2961 docker_data3]# ls docker3.txt docker4.txt host.txt [root@671ef51c2961 docker_data3]# -- 停掉父容器，不影响子容器和主机的同步 [root@671ef51c2961 docker_data3]# ls docker3.txt docker4.txt host.txt host2.txt [root@671ef51c2961 docker_data3]#
主机：
hongcaixia@hongcaixiadeMacBook-Pro Documents % cd host_data3 hongcaixia@hongcaixiadeMacBook-Pro host_data3 % ls hongcaixia@hongcaixiadeMacBook-Pro host_data3 % ls docker3.txt hongcaixia@hongcaixiadeMacBook-Pro host_data3 % ls docker3.txt docker4.txt hongcaixia@hongcaixiadeMacBook-Pro host_data3 % touch host.txt hongcaixia@hongcaixiadeMacBook-Pro host_data3 % ls docker3.txt docker4.txt host.txt hongcaixia@hongcaixiadeMacBook-Pro host_data3 % hongcaixia@hongcaixiadeMacBook-Pro host_data3 % touch host2.txt hongcaixia@hongcaixiadeMacBook-Pro host_data3 % ls docker3.txt docker4.txt host.txt host2.txt hongcaixia@hongcaixiadeMacBook-Pro host_data3 %
父容器stop，不会影响子容器和主机之间的同步
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