默认情况下,在运行中的容器里创建的文件,被保存在一个可写的容器层:
如果容器被删除了,则数据也没有了这个可写的容器层是和特定的容器绑定的,也就是这些数据无法方便的和其它容器共享
Docker主要提供了两种方式做数据的持久化
Data Volume, 由Docker管理,(/var/lib/docker/volumes/ Linux), 持久化数据的最好方式Bind Mount,由用户指定存储的数据具体mount在系统什么位置
Data Volume环境准备本节部分 *** 作需要Linux系统的环境,但是大部分都可以在Windows环境下的Docker进行 *** 作,只有一个 *** 作不行。
准备一个Dockerfile 和 一个 my-cron的文件
Dockerfile
FROM alpine:latest RUN apk update RUN apk --no-cache add curl ENV SUPERCRONIC_URL=https://github.com/aptible/supercronic/releases/download/v0.1.12/supercronic-linux-amd64 SUPERCRonIC=supercronic-linux-amd64 SUPERCRONIC_SHA1SUM=048b95b48b708983effb2e5c935a1ef8483d9e3e RUN curl -fsSLO "$SUPERCRONIC_URL" && echo "${SUPERCRONIC_SHA1SUM} ${SUPERCRONIC}" | sha1sum -c - && chmod +x "$SUPERCRONIC" && mv "$SUPERCRONIC" "/usr/local/bin/${SUPERCRONIC}" && ln -s "/usr/local/bin/${SUPERCRONIC}" /usr/local/bin/supercronic COPY my-cron /app/my-cron WORKDIR /app VOLUME ["/app"] # RUN cron job CMD ["/usr/local/bin/supercronic", "/app/my-cron"]
my-cron
定时任务,没分钟存一次
*/1 * * * * date >> /app/test.txt构建镜像
$ docker image build -t my-cron . $ docker image ls REPOSITORY TAG IMAGE ID CREATED SIZE my-cron latest e9fbd9a562c9 4 seconds ago 24.7MB创建容器(不指定-v参数)
此时Docker会自动创建一个随机名字的volume,去存储我们在Dockerfile定义的volume VOLUME ["/app"]
$ docker run -d my-cron 9a8fa93f03c42427a498b21ac520660752122e20bcdbf939661646f71d277f8f $ docker volume ls DRIVER VOLUME NAME local 043a196c21202c484c69f2098b6b9ec22b9a9e4e4bb8d4f55a4c3dce13c15264 $ docker volume inspect 043a196c21202c484c69f2098b6b9ec22b9a9e4e4bb8d4f55a4c3dce13c15264 [ { "CreatedAt": "2021-06-22T23:06:13+02:00", "Driver": "local", "Labels": null, "Mountpoint": "/var/lib/docker/volumes/043a196c21202c484c69f2098b6b9ec22b9a9e4e4bb8d4f55a4c3dce13c15264/_data", "Name": "043a196c21202c484c69f2098b6b9ec22b9a9e4e4bb8d4f55a4c3dce13c15264", "Options": null, "Scope": "local" } ]
在这个Volume的mountpoint可以发现容器创建的文件
创建容器(指定-v参数)在创建容器的时候通过 -v 参数我们可以手动的指定需要创建Volume的名字,以及对应于容器内的路径,这个路径是可以任意的,不必需要在Dockerfile里通过VOLUME定义
比如我们把上面的Dockerfile里的VOLUME删除
FROM alpine:latest RUN apk update RUN apk --no-cache add curl ENV SUPERCRONIC_URL=https://github.com/aptible/supercronic/releases/download/v0.1.12/supercronic-linux-amd64 SUPERCRonIC=supercronic-linux-amd64 SUPERCRONIC_SHA1SUM=048b95b48b708983effb2e5c935a1ef8483d9e3e RUN curl -fsSLO "$SUPERCRONIC_URL" && echo "${SUPERCRONIC_SHA1SUM} ${SUPERCRONIC}" | sha1sum -c - && chmod +x "$SUPERCRONIC" && mv "$SUPERCRONIC" "/usr/local/bin/${SUPERCRONIC}" && ln -s "/usr/local/bin/${SUPERCRONIC}" /usr/local/bin/supercronic COPY my-cron /app/my-cron WORKDIR /app # RUN cron job CMD ["/usr/local/bin/supercronic", "/app/my-cron"]
重新build镜像,然后创建容器,加-v参数
$ docker image build -t my-cron . $ docker container run -d -v cron-data:/app my-cron 43c6d0357b0893861092a752c61ab01bdfa62ea766d01d2fcb8b3ecb6c88b3de $ docker volume ls DRIVER VOLUME NAME local cron-data $ docker volume inspect cron-data [ { "CreatedAt": "2021-06-22T23:25:02+02:00", "Driver": "local", "Labels": null, "Mountpoint": "/var/lib/docker/volumes/cron-data/_data", "Name": "cron-data", "Options": null, "Scope": "local" } ] $ ls /var/lib/docker/volumes/cron-data/_data my-cron $ ls /var/lib/docker/volumes/cron-data/_data my-cron test.txt
Volume也创建了。
环境清理强制删除所有容器,系统清理和volume清理
$ docker rm -f $(docker container ps -aq) $ docker system prune -f $ docker volume prune -fData Volume 练习 MySQL
使用MySQL官方镜像,tag版本5.7
准备镜像$ docker pull mysql:5.7 $ docker image ls REPOSITORY TAG IMAGE ID CREATED SIZE mysql 5.7 2c9028880e58 5 weeks ago 447MB创建容器
关于MySQL的镜像使用,可以参考 dockerhub https://hub.docker.com/_/mysql?tab=description&page=1&ordering=last_updated
关于Dockerfile Volume的定义,可以参考 https://github.com/docker-library/mysql/tree/master/5.7
$ docker container run --name some-mysql -e MYSQL_ROOT_PASSWORD=my-secret-pw -d -v mysql-data:/var/lib/mysql mysql:5.7 02206eb369be08f660bf86b9d5be480e24bb6684c8a938627ebfbcfc0fd9e48e $ docker volume ls DRIVER VOLUME NAME local mysql-data $ docker volume inspect mysql-data [ { "CreatedAt": "2021-06-21T23:55:23+02:00", "Driver": "local", "Labels": null, "Mountpoint": "/var/lib/docker/volumes/mysql-data/_data", "Name": "mysql-data", "Options": null, "Scope": "local" } ]数据库写入数据
进入MySQL的shell,密码是 my-secret-pw
$ docker container exec -it 022 sh # mysql -u root -p Enter password: Welcome to the MySQL monitor. Commands end with ; or g. Your MySQL connection id is 2 Server version: 5.7.34 MySQL Community Server (GPL) Copyright (c) 2000, 2021, Oracle and/or its affiliates. Oracle is a registered trademark of Oracle Corporation and/or its affiliates. Other names may be trademarks of their respective owners. Type 'help;' or 'h' for help. Type 'c' to clear the current input statement. mysql> show databases; +--------------------+ | Database | +--------------------+ | information_schema | | mysql | | performance_schema | | sys | +--------------------+ 4 rows in set (0.00 sec) mysql> create database demo; Query OK, 1 row affected (0.00 sec) mysql> show databases; +--------------------+ | Database | +--------------------+ | information_schema | | demo | | mysql | | performance_schema | | sys | +--------------------+ 5 rows in set (0.00 sec) mysql> exit Bye # exit
创建了一个叫 demo的数据库
查看data volume
$ docker volume inspect mysql-data [ { "CreatedAt": "2021-06-22T00:01:34+02:00", "Driver": "local", "Labels": null, "Mountpoint": "/var/lib/docker/volumes/mysql-data/_data", "Name": "mysql-data", "Options": null, "Scope": "local" } ] # 这个指令 Linux环境的可以查看 $ ls /var/lib/docker/volumes/mysql-data/_data auto.cnf client-cert.pem ib_buffer_pool ibdata1 performance_schema server-cert.pem ca-key.pem client-key.pem ib_logfile0 ibtmp1 private_key.pem server-key.pem ca.pem demo ib_logfile1 mysql public_key.pem sys $
Windows Docker Desktop
未挂载Volumes时
如果熟悉的话,也可以试试MongoDB https://hub.docker.com/_/mongo
Bind Mount把本机的文件夹挂载到容器里面。就是把本机的文件夹路径与容器的文件路径打通,容器的程序写入到本机的文件夹内。
练习示例例如,目前没有C的环境,无法编译。
hello.c
#includeint main() { printf("hello dockern"); }
PS F:docker> docker container run -it -v ${pwd}:/root gcc:latest root@ccad73dbd28f:/# cd root/ root@ccad73dbd28f:~# ls dockerfile hello.c root@ccad73dbd28f:~# gcc -o hello hello.c root@ccad73dbd28f:~# ls dockerfile hello hello.c root@ccad73dbd28f:~# ./hello hello docker root@ccad73dbd28f:~#
${pwd} 当前目录 就是 F:docke 挂载到容器里
可以当机器不想搭建环境,或者无法兼容某些环境时候,就可以使用docker容器远程开发环境。我用Pycharm工具就有使用虚拟环境连接Docker。
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