默认情况下，在mysql容器中创建新库时需要先运行mysql容器，把需要的sql文件通过docker cp的方式拷贝至容器内，再通过mysql的子命令将sql文件导入。过程比较繁琐，如果是公司的项目部署，可以创建带有公司的项目sql的自定义mysql镜像，避免繁琐的流程。
背景分析
首先拉取官方镜像：
docker pull mysql:5.7.30
查看镜像的构建历史
[root@bochs docker]# docker history mysql:5.7.30
IMAGE CREATED CREATED BY SIZE COMMENT
...
<missing> 29 hours ago /bin/sh -c #(nop) ENTRYPOINT ["docker-entrypoint.sh"] 0B
...
可以发现，默认的entrypoint为docker-entrypoint.sh
进入容器内，可以发现docker-entrypoint.sh其实是个软连接
lrwxrwxrwx 1 root root 34 May 15 20:11 entrypoint.sh -> usr/local/bin/docker-entrypoint.sh
查看此脚本，发现脚本中已经定义了初始化的代码：
1、docker_process_init_file()函数定义了初始文件的格式，其中调用了docker_process_sql来完成新库创建及数据导入。
初始化文件可以是.sh .sql .sql.gz .sql.xz格式中的任一种
docker_process_init_files() {
# mysql here for backwards compatibility "${mysql[@]}"
mysql=( docker_process_sql )
echo
local f
for f; do
case "$f" in
*.sh)
# https://github.com/docker-library/postgres/issues/450#issuecomment-393167936
# https://github.com/docker-library/postgres/pull/452
if [ -x "$f" ]; then
mysql_note "$0: running $f"
"$f"
else
mysql_note "$0: sourcing $f"
. "$f"
fi
;;
*.sql) mysql_note "$0: running $f"; docker_process_sql < "$f"; echo ;;
*.sql.gz) mysql_note "$0: running $f"; gunzip -c "$f" | docker_process_sql; echo ;;
*.sql.xz) mysql_note "$0: running $f"; xzcat "$f" | docker_process_sql; echo ;;
*) mysql_warn "$0: ignoring $f" ;;
esac
echo
done
}
2、docker_process_sql使用mysql命令导入数据库文件
docker_process_sql() {
passfileArgs=()
if [ ‘--dont-use-mysql-root-password‘ = "$1" ]; then
passfileArgs+=( "$1" )
shift
fi
if [ -n "$MYSQL_DATABASE" ]; then
set -- --database="$MYSQL_DATABASE" "$@"
fi
mysql --defaults-extra-file=<( _mysql_passfile "${passfileArgs[@]}") --protocol=socket -uroot -hlocalhost --socket="${SOCKET}" "$@"
}
3、在主函数调用了docker_process_init_file()函数,初始化的文件全部位于/docker-entrypoint-initdb.d/中
365 docker_process_init_files /docker-entrypoint-initdb.d/*
只要把sql文件放入该目录我们就可以通过docker build命令来创建带有自定义库的mysql镜像了。
实现过程
创建新的Dockerfile文件，将所需要的用到的sql文件拷贝到/docker-entrypoint-initdb.d/目录中
FROM mysql:5.7.30
COPY ./mysql/initsql/*.sql /docker-entrypoint-initdb.d/
docker-compose文件如下
version: "3.3"
services:
mysql:
build:
context: .
dockerfile: Dockerfile
image: mysql_modified:v1.0
container_name: mysql_modified
ports:
- target: 3306
published: 3306
protocol: tcp
mode: host
volumes:
- /home/docker/mysql/conf/:/etc/mysql/conf.d/
- /home/docker/mysql/data/:/var/lib/mysql/
environment:
- MYSQL_ROOT_PASSWORD=Zxczxc@123
新建测试用的test.sql文件
注意：如果是用mysqldump导出的sql文件，必须要加上-B参数保留创库语句。
CREATE DATABASE IF NOT EXISTS DB_TEST;
USE DB_TEST;
CREATE TABLE employees (
emp_no INT NOT NULL COMMENT ‘主键‘,
birth_date DATE NOT NULL COMMENT ‘生日‘,
first_name VARCHAR(14) NOT NULL COMMENT ‘用户-姓‘,
last_name VARCHAR(16) NOT NULL COMMENT ‘用户-名‘,
gender ENUM (‘M‘,‘F‘) NOT NULL COMMENT ‘性别‘,
hire_date DATE NOT NULL COMMENT ‘入职时间‘,
PRIMARY KEY (emp_no)
);
INSERT INTO `employees` VALUES
(10001,‘1953-09-02‘,‘Georgi‘,‘Facello‘,‘M‘,‘1986-06-26‘),
(10002,‘1964-06-02‘,‘Bezalel‘,‘Simmel‘,‘F‘,‘1985-11-21‘),
(10003,‘1959-12-03‘,‘Parto‘,‘Bamford‘,‘M‘,‘1986-08-28‘),
(10004,‘1954-05-01‘,‘Chirstian‘,‘Koblick‘,‘M‘,‘1986-12-01‘);
整个构建目录结构如下：
[root@bochs /]# tree home
home
`-- docker
|-- docker-compose.yml
|-- Dockerfile
`-- mysql
|-- conf
| `-- my.cnf
|-- data
`-- initsql
`-- test.sql
5 directories, 4 files
使用docker-compose build命令构建新的带有默认库mysql镜像
[root@bochs docker]# docker-compose build
Building mysql
Step 1/2 : FROM mysql:5.7.30
---> b84d68d0a7db
Step 2/2 : COPY ./mysql/initsql/*.sql /docker-entrypoint-initdb.d/
---> c64103df17a2
Successfully built c64103df17a2
Successfully tagged mysql_modified:v1.0
[root@bochs docker]# docker image ls
REPOSITORY TAG IMAGE ID CREATED SIZE
mysql_modified v1.0 c64103df17a2 32 seconds ago 448MB
mysql 5.7.30 b84d68d0a7db 30 hours ago 448MB
完成镜像创建后使用docker-compose up -d启动该容器并查看数据，新库已成功创建，数据也正常。
[root@bochs docker]# docker-compose up -d
[root@bochs docker]# docker exec -it mysql_modified mysql -uroot -p‘Zxczxc@123‘ -e ‘show databases;‘
mysql: [Warning] Using a password on the command line interface can be insecure.
+--------------------+
| Database |
+--------------------+
| information_schema |
| DB_TEST |
| mysql |
| performance_schema |
| sys |
+--------------------+
[root@bochs docker]# docker exec -it mysql_modified mysql -uroot -p‘Zxczxc@123‘ -e ‘select * from DB_TEST.employees;\G‘
mysql: [Warning] Using a password on the command line interface can be insecure.
+--------+------------+------------+-----------+--------+------------+
| emp_no | birth_date | first_name | last_name | gender | hire_date |
+--------+------------+------------+-----------+--------+------------+
| 10001 | 1953-09-02 | Georgi | Facello | M | 1986-06-26 |
| 10002 | 1964-06-02 | Bezalel | Simmel | F | 1985-11-21 |
| 10003 | 1959-12-03 | Parto | Bamford | M | 1986-08-28 |
| 10004 | 1954-05-01 | Chirstian | Koblick | M | 1986-12-01 |
+--------+------------+------------+-----------+--------+------------+
总结
放入/docker-entrypoint-initdb.d/目录中的文件只会在构建镜像时执行一次
可以将多个数据库放入/docker-entrypoint-initdb.d/中达到批量化创建的目的