How to upload extra modules to odoo container in digital ocean

I have a docker-compose.yml with the configuration for Odoo container, and I have some custom modules.

version: '2'
  services:
    web:
      image: odoo:11.0
      restart: always
      depends_on:
       - db
      ports:
       - "8069:8069"
      volumes:
       - ./custom-modules:/mnt/extra-addons
     db:
       image: postgres:10
       environment:
        - POSTGRES_DB=postgres
        - POSTGRES_PASSWORD=odoo
        - POSTGRES_USER=odoo

And I want to deploy this containers to digital ocean, so I create a docker droplet

$ docker-machine create --driver=digitalocean --digitalocean-access-token=$DO_TOKEN --digitalocean-size=s-1vcpu-1gb odoo
$ eval $(docker-machine env odoo)
$ docker-compose up -d

And i was expecting something like docker uploads my custom-modules/ or something like that but the folder is not available in the docker machine. Any idea on how to do this? Of course I know how to install odoo from scratch in a normal ubuntu droptlet but I want to do this with Docker, but I am new with this technology

Source: StackOverflow