How to map a docker containers directory to the host with docker-compose?

Question

Given following docker-compose.yml setup:

version: '3.7'

services:
  reverse:
    container_name: nginx-reverse-proxy
    hostname: nginx-reverse-proxy
    image: nginx:stable
    ports:
      - 80:80
      - 433:433
    volumes:
      - type: bind
        source: ./config
        target: /etc/nginx
        consistency: consistent

this results in ./config folder being mapped to the container nginx-reverse-proxy and therefore in an empty /etc/nginx directory inside the container.

Goal:
Mapping a folder from container to host. In my example from container /etc/nginx to the host ./config.

My current search constantly results in mapping a directoy from host to container (which i do not want).

Any hints/solutions are appreciated. Thanks!

My current solution is ugly: I created the container with docker and copied the files from /etc/nginx to ./config. Removing the container and using the docker-compose up works and nginx starts because the needed files are already on the host.

Edit: The folder is not present at creation. Docker compose is creating the folder as stated in the docs.

Answer 1

Reading from: Dockers Volume Page

Volumes have several advantages over bind mounts:

New volumes can have their content pre-populated by a container.

---

So a simple docker-compose (inside a folder called nginx):

version: "3.7"
volumes:
  xmpl:

services:
  testnginx:
    image: nginx:stable
    volumes:
      - xmpl:/etc/nginx

Will yield all the files on the host system via:

$ docker-compose up
$ docker inspect nginx_xmpl
...
"Mountpoint": "/var/lib/docker/volumes/nginx_xmpl/_data"

And you can then view the files on the host:

# ls /var/lib/docker/volumes/nginx_xmpl/_data                               
  conf.d       fastcgi_params koi-utf    koi-win  
  mime.types   modules        nginx.conf scgi_params    
  uwsgi_params win-utf

And finally to use it from ./config:

# ln -s /var/lib/docker/volumes/nginx_xmpl/_data ./config
# ls config
  conf.d       fastcgi_params koi-utf    koi-win  
  mime.types   modules        nginx.conf scgi_params    
  uwsgi_params win-utf