如果使用以下.yml运行$docker-compose down，似乎无法持久保存MySQL数据

version: '2'
services:
  # other services

  data:
    container_name: flask_data
    image: mysql:latest
    volumes:
      - /var/lib/mysql
    command: "true"

  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_from:
      - data
    ports:
      - "3306:3306"

我的理解是，在我的data容器中，使用volumes:-/var/lib/mysql将其映射到mysql将数据存储到容器的本地machines目录，由于这种映射，即使容器被破坏，数据也应该保持不变。而MySQL容器只是db的客户端接口，可以看到本地目录，这是因为volumes_from:-data

尝试了这个答案，但没有成功。Docker-编写持久数据故障

编辑

如下所示更改了我的.yml，并创建了一个dir./data，但现在当我运行docker-compose up-build时，mysql容器不会启动，会抛出一个错误：

  data:
    container_name: flask_data
    image: mysql:latest
    volumes:
      - ./data:/var/lib/mysql
    command: "true"

  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_from:
      - data
    ports:
      - "3306:3306"


flask_mysql | mysqld: Can't create/write to file '/var/lib/mysql/is_writable' (Errcode: 13 - Permission denied)
flask_mysql | 2016-08-26T22:29:21.182144Z 0 [Warning] TIMESTAMP with implicit DEFAULT value is deprecated. Please use --explicit_defaults_for_timestamp server option (see documentation for more details).
flask_mysql | 2016-08-26T22:29:21.185392Z 0 [ERROR] --initialize specified but the data directory exists and is not writable. Aborting.