With credentials in an XDG configuration file spotifyd is ready to run, e.g.
as daemon in ~/.xsession or on-demand via clients such as "spotify-qt":

  [spotifyd]
  username = "user@example.com"
  password = "secret"

Alternatively, the rc.d(8) script runs as dedicated user on the system D-Bus
where user keyring services (running on its session D-Bus) are unavailable.

Follow sndio(7) Authentication if both dedicated and your own user shall be
able to play audio at the same time, e.g. on a desktop system:

  # install -D -p -o _spotifyd -m 0600 ~/.sndio/cookie /var/spotifyd/.sndio/cookie
