[Docker学习笔记] Volume数据卷

分手后的思念是犯贱 2021-10-18 07:40 333阅读 0赞

1）将Docker主机数据挂载到容器的三种方式：

volumes：Docker管理宿主机文件系统的一部分（/var/lib/docker/volumes）

bind mounts：可以存储在宿主机系统的任何位置

tmpfs：挂载存储在宿主机系统的内存中，而非写入宿主机的文件系统

[root@localhost ~]# ls /var/lib/docker/volumes/
    metadata.db

2）docker volume

Commands:  
  create      Create a volume  
  inspect     Display detailed information on one or more volumes   可以看挂载点  
  ls              List volumes  
  prune       Remove all unused local volumes  
  rm            Remove one or more volumes

例如，*docker volume create nginx-vol* 创建一个数据卷 nginx-vol，挂载在/var/lib/docker/volumes/nginx-vol/\_data；

*docker run -itd --name=nginx-test --mount src=nginx-vol,dst=/usr/share/nginx/html nginx*，使用数据卷nginx-vol 创建一个容器，对应容器中的路径是/usr/share/nginx/html；

会发现容器路径/usr/share/nginx/html 中的内容和宿主机路径/var/lib/docker/volumes/nginx-vol/\_data中的内容一致

[root@localhost ~]# docker volume ls
    DRIVER              VOLUME NAME
    [root@localhost ~]# docker volume create nginx-vol
    nginx-vol
    [root@localhost ~]# docker volume ls
    DRIVER              VOLUME NAME
    local               nginx-vol
    [root@localhost ~]# docker volume inspect nginx-vol
    [
        {
            "CreatedAt": "2019-08-11T19:21:12+08:00",
            "Driver": "local",
            "Labels": {},
            "Mountpoint": "/var/lib/docker/volumes/nginx-vol/_data",
            "Name": "nginx-vol",
            "Options": {},
            "Scope": "local"
        }
    ]
    [root@localhost ~]# docker run -itd --name=nginx-test --mount src=nginx-vol,dst=/usr/share/nginx/html nginx
    3259c062853631cd60884daeeb970dfd283571eec65cf91ea932e0b2b8d2beff
    [root@localhost ~]#
    [root@localhost ~]# cd /var/lib/docker/volumes/nginx-vol/_data
    [root@localhost _data]# ls
    50x.html  index.html
    [root@localhost _data]# touch test01
    [root@localhost _data]# docker exec nginx-test ls /usr/share/nginx/html
    50x.html
    index.html
    test01
    [root@localhost _data]#

将所有容器删除后，宿主机上的数据还在，重新创建一个容器（例如把80端口映射到本机8888端口）挂载相同路径；在宿主机创建一个html文件如test02.html，写入一些内容，浏览器输入<Host IP addr>:8888/test02.html

[root@localhost ~]# docker rm -f $(docker ps -q -a)
    3259c0628536
    b94f60530a2a
    cc74fb080972
    [root@localhost ~]# cd /var/lib/docker/volumes/nginx-vol/_data
    [root@localhost _data]# ls
    50x.html  index.html  test01
    [root@localhost _data]# echo "<h1>It's rainy today.</h1>" > test02.html
    [root@localhost _data]# cat test02.html
    <h1>It's rainy today.</h1>
    [root@localhost _data]# docker run -itd --name=nginx-test -p 8888:80 --mount src=nginx-vol,dst=/usr/share/nginx/html nginx
    80e7a88804244734223965e90f14e902a04937cc1ad31ce00f5bdf77cf183d56
    [root@localhost _data]#

网页显示效果如下：

![20190810200932812.png][]

由此，第一，可以实现数据持久化；第二，可以共享数据卷，扩展能力强

2.1）docker volume rm nginx-vol 清理数据卷

[root@localhost ~]# docker container stop nginx-test
    nginx-test
    [root@localhost ~]# docker container rm nginx-test
    nginx-test
    [root@localhost ~]# docker volume rm nginx-vol
    nginx-vol
    [root@localhost ~]#

2.2）起容器时不指定源路径，会自动生成一个匿名卷（相对地，之前的例子中创建的是命名卷）

[root@localhost ~]# docker run -itd --name=nginx-test -p 8888:80 --mount src=,dst=/usr/share/nginx/html nginx
    ce86bc7461342daf29fcb758e899a95350dd7fed76818e1b1db891b0090050bf
    [root@localhost ~]# cd /var/lib/docker/volumes/
    [root@localhost volumes]# ls
    6af6c2c94be43c940f2a16064f8de5102be5ec9ab94208579693d819b5212228  metadata.db
    [root@localhost volumes]#

官方文档传送门 -> [https://docs.docker.com/storage/volumes/\#start-a-container-with-a-volume][https_docs.docker.com_storage_volumes_start-a-container-with-a-volume]

3）bind mounts

需注意：第一，如果源目录不存在，不会自动创建，会抛出错误；

第二，如果挂载路径在容器中非空目录，则该目录现有的内容会被隐藏。

[root@localhost ~]# docker run -itd --name=nginx-test --mount type=bind,src=/app/test,dst=/usr/share/nginx/html nginx
    docker: Error response from daemon: invalid mount config for type "bind": bind source path does not exist: /app/test.
    See 'docker run --help'.
    [root@localhost ~]# mkdir -p /app/test
    [root@localhost ~]# docker run -itd --name=nginx-test --mount type=bind,src=/app/test,dst=/usr/share/nginx/html nginx
    c02fd53772aabb26f4fe2784b80484bf8b5a5a35fb88bc21d42942564638d460
    [root@localhost ~]# cd /app/test
    [root@localhost test]# ls
    [root@localhost test]# docker exec -it nginx-test bash
    root@c02fd53772aa:/# cd /usr/share/nginx/html
    root@c02fd53772aa:/usr/share/nginx/html# ls
    root@c02fd53772aa:/usr/share/nginx/html# exit
    exit
    [root@localhost test]# touch testlocal
    [root@localhost test]# docker exec -it nginx-test bash
    root@c02fd53772aa:/# cd /usr/share/nginx/html
    root@c02fd53772aa:/usr/share/nginx/html# ls
    testlocal
    root@c02fd53772aa:/usr/share/nginx/html#

可用 docker inspect <container ID | container name> 验证绑定（找到Mount）

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3d5X2hoeHg_size_16_color_FFFFFF_t_70][]

官方文档传送门 -> [https://docs.docker.com/storage/bind-mounts/\#start-a-container-with-a-bind-mount][https_docs.docker.com_storage_bind-mounts_start-a-container-with-a-bind-mount]

(End)

学习的视频路径 ->  [https://ke.qq.com/course/366769?taid=2769880244132017][https_ke.qq.com_course_366769_taid_2769880244132017]

[20190810200932812.png]: /images/20211018/4397804284c94717bb066816cbd3bf2c.png
[https_docs.docker.com_storage_volumes_start-a-container-with-a-volume]: https://docs.docker.com/storage/volumes/#start-a-container-with-a-volume
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3d5X2hoeHg_size_16_color_FFFFFF_t_70]: /images/20211018/dcc7b1f1f7da4e19ae0622da038a66e0.png
[https_docs.docker.com_storage_bind-mounts_start-a-container-with-a-bind-mount]: https://docs.docker.com/storage/bind-mounts/#start-a-container-with-a-bind-mount
[https_ke.qq.com_course_366769_taid_2769880244132017]: https://ke.qq.com/course/366769?taid=2769880244132017