Docker mysql - run update command/script on image startup - mysql

Question

I wish to build a docker image with an initialised database.
This initial data will contain a default client ref value 'XXX'.
Here's my Dockerfile:
FROM mysql/mysql-server:5.7
COPY data.sql /docker-entrypoint-initdb.d/
When starting up the container of this image, I need to replace the ref value with the user's particular value, 'ABCD', which will come from an environment variable set by a docker compose file.
So the update query to run is something like:
update client set ref='ABCD' where ref='XXX'
How do I get the Dockerfile to do this? I don't think it can be a RUN command as I don't want the update to be part of the image build, but part of the startup of the image (it's fine if it runs this update on every startup).
I have all the usual mysql env varibles set (MYSQL_ROOT_PASSWORD/MYSQL_ROOT_HOST/MYSQL_DATABASE/MYSQL_USER/MYSQL_PASSWORD) and hope to refer to another env var for the desired ref to be setting. Keen to see this could be done as raw commands as well as a script.

Answer 1

You're right,
Everything that you want to be persistent should be in the Dockerfile or in build: section of your docker-compose file.
As you want to have the update only in docker run or docker-compose up phase, you can use CMD or ENTRYPOINT to execute it.
There are several ways, but let me recommend the following one:
docker-compose.yml
version: '3'
services:
your-service:
env_file: ./your-mysql-env-file.env
image: mysql/mysql-server:5.7
volumes:
- ./data.sql:/docker-entrypoint-initdb.d/data.sql
- ./your-init-sql-commands.sql:/docker-entrypoint-initdb.d/your-init-sql-commands.sql
container_name: your-container-name
command:
- /bin/bash
- -c
- |
/etc/init.d/mysqld start
mysql -u ${MYSQL_USER} -p ${MYSQL_PASSWORD} -h ${MYSQL_ROOT_HOST} ${MYSQL_DATABASE} < your-init-sql-commands.sql
[other commands if needed...]
Note that your update client set ref='ABCD' where ref='XXX' should be defined inside your-init-sql-commands.sql. So, if you want to change updates, you won't need to rebuild image.
your-mysql-env-file.env just define inside it your MYSQL env variables if you need them inside.
Note that I've changed your dockerfile by image:section and COPY by volumes: in docker-compose.yml, but all this steps can be also done with Dockerfile and docker run.
If you don't need a multiple command, just change all lines by a single one.
I hope this can be helpful for you.