Diagnose docker.service startup error?

I’m looking at the book “Puppet for Containerization”, which uses Docker (obviously). As part of the puppet provisioning, docker was installed, and it tried to start the service, but startup failed. I saw the following error first:

==> node-01: Error: /Stage[main]/Docker::Service/Service[docker]/ensure: change from stopped to running failed: Could not start Service[docker]: Execution of '/bin/systemctl start docker' returned 1: Job for docker.service failed because the control process exited with error code. See "systemctl status docker.service" and "journalctl -xe" for details.

After I got onto the box with “vagrant ssh”, I ran “systemctl status docker.service”, and saw the following:

● docker.service - Docker Application Container Engine Loaded: loaded (/usr/lib/systemd/system/docker.service; disabled; vendor preset: disabled) Drop-In: /etc/systemd/system/docker.service.d └─service-overrides.conf Active: failed (Result: exit-code) since Thu 2016-06-16 22:45:34 UTC; 33s ago Docs: https://docs.docker.com Process: 4438 ExecStart=/usr/bin/docker -d -H fd:// $OPTIONS $DOCKER_STORAGE_OPTIONS $DOCKER_NETWORK_OPTIONS $BLOCK_REGISTRY $INSECURE_REGISTRY (code=exited, status=125) Main PID: 4438 (code=exited, status=125)

I also ran “journalctl -xe”, but that found nothing.

What else do I need to see to determine what went wrong here?