Why do some host volumes in Docker containers give the error "too many levels of symbolic links"?
This is caused by directories not being automounted when the container is run. I had thought that
/usr/groups/thing was the automount point, but evidently the sub-directories are auto-mounted individually. The solution is to make sure each one is mounted before entering the container:
$ (cd /usr/groups/thing/foo; cd /usr/groups/thing/bar) $ docker run -v /usr/groups/thing -ti imagename /bin/bash # ls /usr/groups/thing/bar d e f