Docker-Compose persistent data MySQL

Question

I can\'t seem to get MySQL data to persist if I run $ docker-compose down with the following .yml

version: \'2\'
services:
  # othe         


        

Answer 1

Actually this is the path and you should mention a valid path for this to work. If your data directory is in current directory then instead of my-data you should mention ./my-data, otherwise it will give you that error in mysql and mariadb also.

volumes:
 ./my-data:/var/lib/mysql

Answer 2

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

Answer 3

You have to create a separate volume for mysql data.

So it will look like this:

volumes_from:
  - data
volumes:
  - ./mysql-data:/var/lib/mysql

And no, /var/lib/mysql is a path inside your mysql container and has nothing to do with a path on your host machine. Your host machine may even have no mysql at all. So the goal is to persist an internal folder from a mysql container.

Answer 4

There are 3 ways:

First way

You need specify the directory to store mysql data on your host machine. You can then remove the data container. Your mysql data will be saved on you local filesystem.

Mysql container definition must look like this:

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:
 - /opt/mysql_data:/var/lib/mysql
ports:
  - "3306:3306"

Second way

Would be to commit the data container before typing docker-compose down:

docker commit my_data_container
docker-compose down

Third way

Also you can use docker-compose stop instead of docker-compose down (then you don't need to commit the container)

Answer 5

Adding on to the answer from @Ohmen, you could also add an external flag to create the data volume outside of docker compose. This way docker compose would not attempt to create it. Also you wouldn't have to worry about losing the data inside the data-volume in the event of $ docker-compose down -v. The below example is from the official page.

version: "3.8"

services:
  db:
    image: postgres
    volumes:
      - data:/var/lib/postgresql/data

volumes:
  data:
    external: true