[docker] Where are Docker images stored on the host machine?

I couldn't resolve the question with Docker version 18.09 on macos using the above answers and tried again.

The only actual solution for me was using this docker-compose.yml configuration:

version: '3.7'
...
  services:
    demo-service:
      volumes:
        - data-volume:/var/tmp/container-volume

volumes:
  data-volume:
    driver: local
    driver_opts:
      type: none
      o: bind
      device: /tmp/host-volume

After launching with docker-compose up I finally had /tmp/host-volume from macos shared as writeable volume from within the container:

> docker exec -it 1234 /bin/bash
bash-4.4$ df
Filesystem           1K-blocks      Used Available Use% Mounted on
...
osxfs                488347692 464780044  21836472  96% /var/tmp/container-volume

Hope this helps others too.