● docker.service - Docker Application Container Engine
   Loaded: loaded (/nix/store/sa6j8ak0ci02ic1i3wx80gyar59qkg9a-unit-docker.service/docker.service)
   Active: failed (Result: exit-code) since Sat 2015-07-04 07:43:02 EDT; 1min 10s ago
  Process: 10900 ExecStartPost=/nix/store/5j9spw5hphy4hjjbb2zdhz1dw8b7vhmc-unit-script/bin/docker-post-start (code=exited, status=0/SUCCESS)
  Process: 10899 ExecStart=/nix/store/gk6w0yga1vl8gy4q8i6zscp71b96agw2-docker-1.6.0/bin/docker --daemon=true --group=docker (code=exited, status=1/FAILURE)
 Main PID: 10899 (code=exited, status=1/FAILURE)

Jul 04 07:43:01 crocodile docker[10899]: time="2015-07-04T07:43:01-04:00" level=info msg="Listening for HTTP on unix (/var/run/docker.sock)"
Jul 04 07:43:01 crocodile systemd[1]: Started Docker Application Container Engine.
Jul 04 07:43:01 crocodile docker[10899]: time="2015-07-04T07:43:01-04:00" level=info msg="+job init_networkdriver()"
Jul 04 07:43:01 crocodile docker[10899]: time="2015-07-04T07:43:01-04:00" level=warning msg="Running modprobe bridge nf_nat failed with message: , error: exit status 1"
Jul 04 07:43:01 crocodile docker[10899]: Could not find a free IP address range for interface 'docker0'. Please configure its address manually and run 'docker -b docker0'
Jul 04 07:43:01 crocodile docker[10899]: time="2015-07-04T07:43:01-04:00" level=info msg="-job init_networkdriver() = ERR (1)"
Jul 04 07:43:02 crocodile docker[10899]: time="2015-07-04T07:43:02-04:00" level=fatal msg="Shutting down daemon due to errors: Could not find a free IP address range for interface 'docker0'. Please configure its address manually and run 'docker -b docker0'"
Jul 04 07:43:02 crocodile systemd[1]: docker.service: main process exited, code=exited, status=1/FAILURE
Jul 04 07:43:02 crocodile systemd[1]: Unit docker.service entered failed state.
Jul 04 07:43:02 crocodile systemd[1]: docker.service failed.