$ sudo mkdir /etc/systemd/system/docker.service.d/
$ sudo vim /etc/systemd/system/docker.service.d/startup_options.conf
[Service]
ExecStart=
ExecStart=/usr/bin/dockerd -H unix:///var/run/docker.sock -H tcp://0.0.0.0:2375 --insecure-registry registry.yourdomain.com --insecure-registry registry.yourdomain2.com