Run bash script after MySQL Docker container starts (every time, not just the initial time) - mysql

Question

I am trying to get a bash script to run when my MySQL container starts. Not the initial time when there are no databases to create, but subsequent times (so placing the files in docker-entrypoint-initdb.d will not work).
My objective is to re-build my container with some database upgrade scripts (schema changes, etc). The thought being I deploy the container with the initial scripts and deploy subsequent updates with my database upgrades as the application ages. It seems like this would be an easy task, but I am having trouble.
Most of the things I have tried came from suggestions I found googling. Here are things I have tried with no success:
Modify the entrypoint.sh (and /usr/local/bin/docker-entrypoint.sh) in the Dockerfile build to add in a call to my script.
This does not even seem to be called, which I suspect is a sign, but my database starts (also note it creates my schema fine the first time)
I do this with a RUN sed in my Dockerfile and have confirmed my changes exist after the container starts
Tried running my script on startup by:
adding a script to /etc/r.d/rc.local
adding a restart cron job (well, I tried, but the Oracle Linux distro doesn’t have it)
— Modifying the /etc/bashrc
— Adding a script to /etc/profile.d/
— Appending to /etc/profie.d/sh.local
Tried adding a command to my docker-compose.yml, but it said that wasn’t found.
My actual database upgrade script works great when I log in to the container manually and execute it. All of my experiments above have been just touching a file or echoing to a file as a proof of concept. Once I get that working, I'll add in the logic to wait for MySQL to start and then run my actual script.
Dockerfile:
FROM mysql:8.0.32
VOLUME /var/lib/mysql
## these are my experiments
RUN sed -i '/main "$#"/a echo "run the script here" > /usr/tmp/XXX' /entrypoint.sh
RUN sed -i '/main "$#"/a echo "run the script here" > /usr/tmp/XXX' /usr/local/bin/docker-entrypoint.sh
RUN echo "touch /usr/tmp/XXX" >> /etc/profile.d/sh.local
RUN sed -i '/doublesourcing/a echo “run the script here > /usr/tmp/XXX' etc/bashrc
I build and run it using:
docker build -t mysql-database -f Dockerfile .
docker run -it --rm -d -p 3306:3306 --name database -v ~/Docker-Volume-Share/database:/var/lib/mysql mysql-database
Some other information that may be useful
I am using a volume on the host. I’ve run my experiments with an existing schema as well as by deleting this directory so it starts fresh
I am using mysql:8.0.32 as the image (Oracle Linux Server release 8.7)
Docker version 20.10.22, build 3a2c30b
Host OS is macOS 13.2.1
Thanks in advance for any tips and guidance!

Answer 1

It sounds like you are trying to run a script after the MySQL container has started and the initial setup has been completed. Here are a few suggestions:
1-Use a custom entrypoint script
You can create a custom entrypoint script that runs after the default entrypoint script included in the MySQL container image. In your Dockerfile, copy your custom entrypoint script into the container and set it as the entrypoint. Here's an example:
FROM mysql:8.0.32
COPY custom-entrypoint.sh /usr/local/bin/
RUN chmod +x /usr/local/bin/custom-entrypoint.sh
ENTRYPOINT ["custom-entrypoint.sh"]
In your custom entrypoint script, you can check if the database already exists and run your upgrade script if it does. Here's an example:
#!/bin/bash
set -e
# Run the default entrypoint script
/docker-entrypoint.sh "$#"
# Check if the database already exists
if mysql -uroot -p"$MYSQL_ROOT_PASSWORD" -e "use my_database"; then
# Run your upgrade script
/path/to/upgrade-script.sh
fi
2-Use a Docker Compose file
If you're using Docker Compose, you can specify a command to run after the container has started. Here's an example:
version: '3'
services:
database:
image: mysql:8.0.32
volumes:
- ~/Docker-Volume-Share/database:/var/lib/mysql
environment:
MYSQL_ROOT_PASSWORD: mypassword
command: >
bash -c "
/docker-entrypoint.sh mysqld &
while ! mysqladmin ping -hlocalhost --silent; do sleep 1; done;
/path/to/upgrade-script.sh
"
This command runs the default entrypoint script in the background, waits for MySQL to start, and then runs your upgrade script.
I hope these suggestions help you achieve your goal!