creates multiple databases on MySQL Docker by using an script

db1.sql

-- This file is placed at ./initdb/sql/db1.sql

-- SQL for initializing db1
CREATE TABLE table1 (id int NOT NULL PRIMARY KEY, name varchar(50) NOT NULL);

db2.sql

-- This file is placed at ./initdb/sql/db2.sql

-- SQL for initializing db2
CREATE TABLE table2 (id int NOT NULL PRIMARY KEY, name varchar(50) NOT NULL);

docker_compose.yml

version: "3"
services:
  mysql:
    image: mysql:5.7
    ports:
      - "3306:3306"
    environment:
      MYSQL_RANDOM_ROOT_PASSWORD: 1
      MYSQL_USER: your_user
      MYSQL_PASSWORD: your_password
    volumes:
      - ./initdb:/docker-entrypoint-initdb.d

init.sh

#!/bin/bash

# This file is placed at ./initdb/init.sh

docker_process_sql () {
  mysql -uroot -p"${MYSQL_ROOT_PASSWORD}" "$@"
}

docker_process_sql << EOS
CREATE DATABASE db1;
CREATE DATABASE db2;
GRANT ALL ON db1.* TO '$MYSQL_USER'@'%';
GRANT ALL ON db2.* TO '$MYSQL_USER'@'%';
FLUSH PRIVILEGES;
EOS

docker_process_sql db1 < /docker-entrypoint-initdb.d/sql/db1.sql
docker_process_sql db2 < /docker-entrypoint-initdb.d/sql/db2.sql