https://bugzilla.redhat.com/show_bug.cgi?id=1195525
--- Comment #1 from Lokesh Mandvekar lsm5@redhat.com --- Hi Benjamin, assuming you haven't added a dockerroot group yourself, please note: the default 'dockerroot' created by the rpm is a user and not a group. So root:dockerroot won't work as expected.
If you'd like non-root users (users in group 'docker' for instance) to be able to use docker, simplest would be to append the -G | --group="docker" option to the docker daemon.
HTH.