Docker容器數(shù)據(jù)卷的基本操作

更新時間：2023年06月12日 10:22:17 作者：我可能是個假開發(fā)

為了能保存數(shù)據(jù)在docker中我們使用卷，本文主要介紹了Docker容器數(shù)據(jù)卷的基本操作，文中通過示例代碼介紹的非常詳細，對大家的學習或者工作具有一定的參考學習價值，需要的朋友們下面隨著小編來一起學習學習吧

一、概念

1.定義

卷就是目錄或文件，存在于一個或多個容器中，由docker掛載到容器，但不屬于聯(lián)合文件系統(tǒng)，因此能夠繞過Union File System提供一些用于持續(xù)存儲或共享數(shù)據(jù)的特性。
卷的設(shè)計目的就是數(shù)據(jù)的持久化，完全獨立于容器的生存周期，因此Docker不會在容器刪除時刪除其掛載的數(shù)據(jù)卷

2.作用：

將運用與運行的環(huán)境打包鏡像，run后形成容器實例運行，但是我們對數(shù)據(jù)的要求希望是持久化的。
Docker容器產(chǎn)生的數(shù)據(jù)，如果不備份，那么當容器實例刪除后，容器內(nèi)的數(shù)據(jù)自然也就沒有了。
為了能保存數(shù)據(jù)在docker中則使用卷。

3.特點：

數(shù)據(jù)卷可在容器之間共享或重用數(shù)據(jù)
卷中的更改可以直接實時生效
數(shù)據(jù)卷中的更改不會包含在鏡像的更新中
數(shù)據(jù)卷的生命周期一直持續(xù)到?jīng)]有容器使用它為止

二、添加容器卷

運行一個帶有容器卷存儲功能的容器實例：docker run -it --privileged=true -v /宿主機絕對路徑目錄:/容器內(nèi)目錄鏡像名

Docker掛載主機目錄訪問如果出現(xiàn)cannot open directory .: Permission denied
解決辦法：在掛載目錄后多加一個--privileged=true參數(shù)

1.宿主vs容器之間映射添加容器卷

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 -- 宿主機在該目錄建立了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  -- 宿主機在該文件寫入了write in host
write in docker
write in host
[root@c61d4745b6e8 docker_data]#

主機操作：

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 命令查看容器掛載信息：

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，主機在掛載目錄修改內(nèi)容，當容器啟動之后依舊可以同步到信息：

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]#

主機操作：在容器停止之后創(chuàng)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.添加讀寫映射規(guī)則

默認是可讀可寫
設(shè)置只讀限制：容器實例內(nèi)部被限制，只能讀取不能寫 docker run -it --privileged=true -v /宿主機絕對路徑目錄:/容器內(nèi)目錄:ro 鏡像名

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 -- 在主機中創(chuàng)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]#

主機操作：

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、卷的繼承和共享

docker run -it --privileged=true --volumes-from 父類 --name 容器名鏡像名

第一個容器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，不影響子容器和主機的同步
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 ~ %?
-- 父容器恢復，主機和子容器的操作可以同步過來
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]#

第二個容器my_centos4: 繼承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，不影響子容器和主機的同步
[root@671ef51c2961 docker_data3]# ls
docker3.txt ?docker4.txt ?host.txt ?host2.txt
[root@671ef51c2961 docker_data3]#?

主機：

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，不會影響子容器和主機之間的同步

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