Expose /etc/docker/registry as a volume

[aol-nnov]

... to allow providing config.yml via volume in, say, docker-compose.

By now, constructs like

    volumes:
      - registry-config:/etc/docker/registry/

have no effect and volume with config.yml does not override the shipped file.

[milosgajdos]

Im not sure I follow but we have integration tests in the dist repo and never had a problem with this https://github.com/distribution/distribution/blob/675d7e27f59c9d332418315adb20f02c20593cea/tests/docker-compose-e2e-cloud-storage.yml#L40-L61

[aol-nnov]

@milosgajdos, to my understanding, conf-e2e-cloud-storage.yml in the aforementioned test is a file on the local fs. I propose storing it in the docker volume.

I.e. adding /etc/docker/registry/ here

[milosgajdos]

I get what you want, but I'm not sure why or what problem will that solve for users.

[aol-nnov]

I get what you want, but I'm not sure why

If one is controlling remote docker daemon (i.e. DOCKER_HOST=ssh://remote docker compose up -d) the approach you're referring to simply does not work. That's all...