looks like you can do this to get the root dir of the container but it's not ideal:
```
$ docker inspect musicbrainz-website-prod | jq '.[].GraphDriver.Data.MergedDir'
"/var/lib/docker/overlay2/f98e2ac3f3e62f964d7a2a24eef7c0e3cd96a783da624e8a0d7600dff094fde9/merged"
```