(Docker notes): Container data volume concept, MySQL synchronization data case

table of Contents

Container data volume

What is a container data volume?

Use data volume

MySQL sync data

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Container data volume

What is a container data volume?

• Package the application and environment into a mirror!
• data? If the data is in the container, then we delete the container and the data will be lost. Requirements: data can be persisted
• MySQL, the container is deleted, and the database is deleted. Requirements : MySQL data can be stored locally
• There can be a data sharing technology between containers. The data generated in the Docker container is synchronized to the local .
• This is the volume technology : the mounting of directories, the directories in our containers are mounted on Linux.

• To sum up one sentence: the persistence and synchronization operations of containers can also share data between containers !
   

Use data volume

• Method 1: directly use the command to mount 

docker run -it -v 主机目录:容器内目录

• Test: Mount the container's home directory to the ceshi directory under the host's home directory

 docker run -it -v /home/ceshi:/home centos /bin/bash

• After entering the container, enter the home directory and create a new file

touch test.java
ls 查看目录下的内容，能看到这个文件

• Switch to the host at this time, or open a terminal to view the ceshi directory under the host's home directory

cd /home/ceshi
ls 查看目录下的内容，发现 test.java 文件已经同步过来了

• Let's test again. Can the data be synchronized after we turn off the container?
  • 1. Exit first to exit the container
  • 2. docker ps check if the container is really stopped
  • 3. On the host, modify the file vim /home/ceshi/test.java
  • 4. docker start starts the container
  • 5. View the content of the file in the container cat /home/test.java
• It can be found that the content of the file is the same as the previous modification, indicating that the file has been synchronized

• The advantage of this method is that future modifications only need to be modified locally, and the container will be automatically synchronized.
• docker inspect view mount information

MySQL sync data

• Get the mysql mirror here to use version 5.7

docker pull mysql:5.7

• Run the container to mount data and configuration files. Note that mysql startup requires a configuration password

docker run -d -p 3310:3306 -v /home/mysql/conf:/etc/mysql/conf.d -v /home/mysql/data:/var/lib/mysql -e MYSQL_ROOT_PASSWORD=123456 --name mysql01 mysql:5.7

• Parameter Description:
  • -d run in the background
  • -p port mapping
  • -V volume mount
  • -e environment configuration
  • --name container name
• After the startup is successful, you can use navicat to connect to mysql or docker exec -it to enter the container mysql -p to enter the mysql console
• Create a database, and then view the mapped path on the host, you can view the newly created database file

• Delete and adjust this container docker rm -f mysql01
• Go to the host to view the files under the path cd /home/mysql/data
• As a result, the file still exists and is not lost, which realizes the function of container data persistence