如何创建保存 MySQL 容器数据到 docker 图像？

Question

Like the title says, I'm running a mysql container on docker. I've another java application running on another docker container and they can communicate with each other. However, each time I have to make some tweaks to my mysql container, I've to rerun it and the data is lost. Is there any way for me to commit all those data changes to another docker image so that I can reuse that particular image to create a mysql container having all the data? Thanks

Answer 1

You will need to create a docker volume to maintain that information.

From the doc

Create a data directory on a suitable volume on your host system, eg /my/own/datadir.

Start your mysql container like this:

$ docker run --name some-mysql -v /my/own/datadir:/var/lib/mysql -e MYSQL_ROOT_PASSWORD=my-secret-pw -d mysql:tag

Answer 2

Storage is decoupled from applications when you containerize them. They are designed this way on purpose so that our containers can be as thin as possible.

If you need data to persist in between the destruction and recreation of a container, then you will need to make use of a "volume".

In ELI5 terms, a volume is basically a flash drive for a container. You store it separately, and connect containers to it through a mount point. You then instruct the applications in your containers to write data to that mount point -- that way the data is stored externally to your actual container.

More information can be found here: https://docs.docker.com/storage/volumes/