Problem statement:

I want to create 2 databases inside one MySQL container and have the user of first database full access to 2nd database. With official mysql image one can easily create a database, and allow a user access to that database. But, creating a 2nd database is not easily provisioned.


Docker images work on the concept of layers. Each new command so to speak creates a new layer and here in lies our solution.

Simply create a SQL file with following commands:

# Create second_db database if it doesn't exist
# Grant all privilidges on second_db to org_user
GRANT ALL PRIVILEGES ON second_db.* TO 'org_user' identified by 'org_user_password';

Let's say you created a file called create_second_db.sql in your project folder (or wherever you really want it to be). Than you can mount this file into docker /docker-entrypoint-initdb.d folder. Files in this folder are loaded in alphabetical order at startup time under root user.

Below is the corresponding Dockerfile (that would mount the create_second_db.sql into the /docker-entrypoint-initdb.d) folder:

# Use base mysql image with tag 5.7
FROM mysql:5.7
# Copy our custom SQL file to /docker-entrypoint-initdb.d folder
COPY ./create_second_db.sql /docker-entrypoint-initdb.d/create_second_db.sql

NOTE: You can mount as many SQL files as you would like into that folder.

Once you have created the image (via docker build), than when you start the container, that container would have 2 databases created.

Build the image

docker build -t custom_mysql -f Dockerfile .</code>

Start the container:

docker run --name custom_mysql \
-e MYSQL_ROOT_PASSWORD=my-secret-pw \
-e MYSQL_USER=org_user \
-e MYSQL_PASSWORD=org_user_password \
-e MYSQL_DATABASE=first_db \
-d custom_mysql


# rhasija ~/tmp/docker
$ docker exec -it 0fdbf85f6218 /bin/bash
root@0fdbf85f6218:/# mysql -u root -p
Enter password:
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 2
Server version: 5.7.22 MySQL Community Server (GPL)

Copyright (c) 2000, 2018, Oracle and/or its affiliates. All rights reserved.

Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

mysql> show databases;
| Database           |
| information_schema |
| first_db           |
| mysql              |
| performance_schema |
| second_db          |
| sys                |
6 rows in set (0.00 sec)


Notice first_db and second_db above.

Boom! Job done. Let's open champagne! ;-)

Comments / questions welcome!

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