Docker does not start and returns an error

Failed to start Docker Application Container Engine.

Error: In newer versions of Docker (1.12+) for CentOS, overlay2 is not a supported filesystem and Docker might not start with the following message:

-- Unit docker.service has begun starting up.
Aug 06 12:47:01 ip-172-31-24-242 dockerd-current[1622]: time="2018-08-06T12:47:01.431682737-04:00" level=warning msg="could not change group /var/run/docker.sock
STORAGE_DRIVER=devicemapper
Aug 06 12:47:01 ip-172-31-24-242 dockerd-current[1622]: time="2018-08-06T12:47:01.433641166-04:00" level=info msg="libcontainerd: new containerd process, pid: 16
Aug 06 12:47:02 ip-172-31-24-242 dockerd-current[1622]: time="2018-08-06T12:47:02.440563079-04:00" level=warning msg="overlay2: the backing xfs filesystem is for
Aug 06 12:47:02 ip-172-31-24-242 dockerd-current[1622]: Error starting daemon: SELinux is not supported with the overlay2 graph driver on this kernel. Either boo
Aug 06 12:47:02 ip-172-31-24-242 systemd[1]: docker.service: main process exited, code=exited, status=1/FAILURE
Aug 06 12:47:02 ip-172-31-24-242 systemd[1]: Failed to start Docker Application Container Engine.
-- Subject: Unit docker.service has failed

Solution: To resolve this error, open the following files in an editor:

/etc/sysconfig/docker-storage
/etc/sysconfig/docker-storage-setup

For example:

vi /etc/sysconfig/docker-storage
vi /etc/sysconfig/docker-storage-setup

Next, in each of the files, change "overlay2" to "devicemapper".