在Docker中声明卷

我正在使用docker-app生成的docker-compose文件

docker-app  render | docker-compose -f - up

docker应用程序文件如下所示，并且可以正常工作。但是我无法使用卷。

我在使用docker run命令时使用-v参数...

-v /my/custom3399:/etc/mysql/conf.d  
-v /storage/mysql/datadir3399:/var/lib/mysql 

如何在撰写文件中声明卷？

# vi hello.dockerapp
# This section contains your application metadata.
# Version of the application
version: 0.1.0
# Name of the application
name: hello
# A short description of the application
description:
# Namespace to use when pushing to a registry. This is typically your Hub username.
#namespace: myHubUsername
# List of application maitainers with name and email for each
maintainers:
  - name: root
    email:
# Specify false here if your application doesn't support Swarm or Kubernetes
targets:
  swarm: false
  kubernetes: false

--
# This section contains the Compose file that describes your application services.

version: "3.5"
services:
  mysql:
    image: ${mysql.image.version}
    environment:
      MYSQL_ROOT_PASSWORD: india${mysql.port}
    ports:
      - "${mysql.port}:3306"


--
# This section contains the default values for your application settings.
mysql.image.version: shantanuo/mysql:5.7
mysql.port: 3391

更新：

上面提到的脚本效果很好。但是，一旦添加卷，就会收到错误消息：

version: "3.5"
services:
  mysql:
    image: ${mysql.image.version}
    environment:
      MYSQL_ROOT_PASSWORD: india${mysql.port}
    ports:
      - "${mysql.port}:3306"
    volumes:
      - type: volume
        source: mysql_data
        target: /var/lib/mysql

volumes:
  mysql_data:
    external: true

错误是：

docker-app  render | docker-compose -f - up
Recreating e5c833e2187d_hashi_mysql_1 ... error

ERROR: for e5c833e2187d_hashi_mysql_1  Cannot create container for service mysql: Duplicate mount point: /var/lib/mysql

ERROR: for mysql  Cannot create container for service mysql: Duplicate mount point: /var/lib/mysql
ERROR: Encountered errors while bringing up the project.

如评论中所述，呈现的输出如下：

#  /usr/local/bin/docker-app  render
version: "3.5"
services:
  mysql:
    environment:
      MYSQL_ROOT_PASSWORD: india3391
    image: shantanuo/mysql:5.7
    ports:
    - mode: ingress
      target: 3306
      published: 3391
      protocol: tcp
    volumes:
    - type: volume
      source: mysql_data
      target: /var/lib/mysql
volumes:
  mysql_data:
    name: mysql_data
    external: true