ERROR: In file './docker-compose.yml', volume must be a mapping not a string

Question

Question: Why do I get this error?

ERROR: In file \'./docker-compose.yml\', volume \'mariavolume\' must be a mapping not a string.

Answer 1

For me this works:

In #docker_compose.yml:

volumes:
  postgres_data: {}
  static: { }

Answer 2

Try this:

version: '2'
services:
  ...
  db:
    image: mariadb
    restart: always
    environment:
      MYSQL_ROOT_PASSWORD: example
    volumes:
      - ~/mariadb:/var/lib/mysql