Commit Data in a MySQL Container

Commit data in a mysql container

The official mysql image stores data in a volume. Normally this is desired so that your data can persist beyond the life span of your container, but data volumes bypass the Union File System and are not committed to the image.

You can accomplish what you're trying to do by creating your own mysql base image with no volumes. You will then be able to add data and commit it to an image, but any data added to a running container after the commit will be lost when the container goes away.

Docker commit does not actually commit

Like David Maze pointed out, the original images I am building upon are already using volumes so my custom images are "inheriting" those volumes - even though I am not explicitly declaring any volumes in my own yaml file.
Couldn't find that documented anywhere I searched, so I hope this will help other beginners.

How to create a save MySQL container data to a docker image?

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, e.g. /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

Docker-Compose persistent data MySQL

The data container is a superfluous workaround. Data-volumes would do the trick for you. Alter your docker-compose.yml to:

version: '2'
services:
  mysql:
    container_name: flask_mysql
    restart: always
    image: mysql:latest
    environment:
      MYSQL_ROOT_PASSWORD: 'test_pass' # TODO: Change this
      MYSQL_USER: 'test'
      MYSQL_PASS: 'pass'
    volumes:
      - my-datavolume:/var/lib/mysql
volumes:
  my-datavolume:

Docker will create the volume for you in the /var/lib/docker/volumes folder. This volume persist as long as you are not typing docker-compose down -v

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