Overcloud deployment fails for SR-IOV compute with "docker pull failed: Cannot connect to the Docker daemon at unix:///var/run/docker.sock. Is the docker daemon running?"

Issue

• Overcloud deploy is failing with below messages in /var/log/messages on the sriov compute nodes:

Jan 22 12:33:44 overcloud-computesriov-0 os-collect-config[16964]: "2019-01-22 12:33:28,895 INFO: 34438 -- Pulling image: x.x.x.x:8787/rhosp13/openstack-neutron-server:13.0-69",
Jan 22 12:33:44 overcloud-computesriov-0 os-collect-config[16964]: "2019-01-22 12:33:28,896 INFO: 34439 -- Pulling image: x.x.x.x:8787/rhosp13/openstack-nova-compute:13.0-75",
Jan 22 12:33:44 overcloud-computesriov-0 os-collect-config[16964]: "2019-01-22 12:33:31,914 WARNING: 34439 -- docker pull failed: Cannot connect to the Docker daemon at unix:///var/run/docker.sock. Is the docker daemon running?",
Jan 22 12:33:44 overcloud-computesriov-0 os-collect-config[16964]: "",
Jan 22 12:33:44 overcloud-computesriov-0 os-collect-config[16964]: "2019-01-22 12:33:31,914 WARNING: 34438 -- docker pull failed: Cannot connect to the Docker daemon at unix:///var/run/docker.sock. Is the docker daemon running?",
Jan 22 12:33:44 overcloud-computesriov-0 os-collect-config[16964]: "2019-01-22 12:33:31,914 WARNING: 34438 -- retrying pulling image: x.x.x.x:8787/rhosp13/openstack-neutron-server:13.0-69",
Jan 22 12:33:44 overcloud-computesriov-0 os-collect-config[16964]: "2019-01-22 12:33:31,914 WARNING: 34439 -- retrying pulling image: x.x.x.x:8787/rhosp13/openstack-nova-compute:13.0-75",
Jan 22 12:33:44 overcloud-computesriov-0 os-collect-config[16964]: "2019-01-22 12:33:34,942 WARNING: 34439 -- docker pull failed: Cannot connect to the Docker daemon at unix:///var/run/docker.sock. Is the docker daemon running?",

• When I query the registry I can see the image/tags it's looking for.