Initialize MySQL database when docker container starts

  brief introduction ： Docker It's used more and more in development , Recently, I made a Spring Boot application , To facilitate deployment Mysql Also on the Docker Run in . So how to initialize SQL Scripts and data ？ Let's take a look .

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1. Preface
Docker It's used more and more in development , Recently, I made a Spring Boot application , To facilitate deployment Mysql Also on the Docker Run in . So how to initialize SQL Scripts and data ？
I have two traditional solutions here . The first option is to manually import after the container is started , too low No, No . The second one is Spring Boot Client connection Mysql Initializes the database when the container , You can refer to flyway Database version control , But it depends on the capabilities of the client . Can we do it Mysql When the container starts, it initializes the database itself ？ Certainly. ！ Today, let's demonstrate . See the end of the text for all codes .
2. principle
When Mysql When the container is first started , Will be in /docker-entrypoint-initdb.d Scan under Directory .sh,.sql,.sql.gz Files of type . If these types of files exist , They will be executed to initialize a database . These files are executed in alphabetical order . By default, they initialize the... Declared when the container is started MYSQL_DATABASE Variable defined in the database , For example, the following command initializes a REGION_DB database ：

If your startup command does not specify a database, it must be in the database DDL The database is declared and specified in the script . Otherwise, the following exception will be implemented ：

Then we will use this mechanism to realize Docker Initialize the database when the container starts .
3. Customize Dockerfile
We write our own Dockerfile To meet our needs , Here we use Mysql:5.7 For example . There may be some differences between different versions , You need to read the official documents in detail . The script is as follows ：

• First step , Introduce the official Mysql:5.7 Docker Mirror image .
• The second step , No practical significance , Mainly the author 、 Organizational information .
• The third step , Very important ！ I didn't configure the third line , Results after running the container, it was found that all the Chinese characters of the initialization data were garbled . Therefore, you need to modify before initializing the database Mysql Coding and other configurations , I'll change the time zone here to +8:00.
• Step four , Copy the script that contains the database ./sql Folder to mirror /tmp/sql Next .
• Step five , Use mv The command copies all the files in the folder in step 4 .sql File copy to /docker-entrypoint-initdb.d Next , In this way, we can make use of 2. The mechanism of the chapter initializes the database .
• Step six , Delete the used temporary directory .

Then you can build a custom image by using the build image command Mysql Mirror image ：

adopt mysql:5.7c Mirror starts with a name of mysql-service The container of ,root The password for 123456, And persist the data to the host D:/mysql/data Next ：

docker run --name mysql-service -v d:/mysql/data:/var/lib/mysql -p 3306:3306 -e MYSQL_ROOT_PASSWORD=123456 -d mysql:5.7c

Tips: ： You can go through SHOW VARIABLES LIKE 'character%' See if the character set is changed to utf8mb4, It can also be done through SHOW VARIABLES LIKE '%time_zone%' Check whether the time zone is East 8 .
4. summary
Today, we customize a program that can initialize the database Mysql Mirror image , It is convenient for us to deploy . You can also refer to this idea to customize other things you need Docker Mirror image .

In this paper, from ：Docker Initialize when the container starts Mysql database - Alicloud developer community