docker-compose 中的 MariaDB 卷清除数据

Question

I'm using the yobasystems/alpine-mariadb docker image to run an instance for a development environment. I'm mounting the data directory for MySQL to a docker volume and this has worked in the past. Every so often I lose data but not the table structure and I cannot work out why.

db:
    image: yobasystems/alpine-mariadb
    restart: always
    environment:
      - MYSQL_ROOT_PASSWORD=password
      - MYSQL_DATABASE=database
      - MYSQL_USER=user
      - MYSQL_PASSWORD=password
    ports:
      - "33333:3306"
    volumes:
      - mariadb:/var/lib/mysql

Answer 1

I suspect that in your case the volume is getting removed(may be via docker-compose down -v or dockere-compose rm -v ).

Please specify that the volume is external using -

volumes:
  mariadb:
    external: true

From docker docs - external: If set to true, specifies that this volume has been created outside of Compose. docker-compose up does not attempt to create it, and raises an error if it doesn't exist.

You may create the volume prior to docker-compose up with docker volume create mariadb