Why access to resource being denied while openstack overcloud image prepare in RHOSP 13 ?

Issue

• Overcloud container image prepare fails as below,

> (undercloud) [stack@director ~]$ openstack overcloud container image prepare \
>   --namespace=rhosp13 \
>   --prefix=openstack- \
>   --output-images-file /home/stack/satellite_images \
>   --tag-from-label {version}-{release} \
>   -e /usr/share/openstack-tripleo-heat-templates/environments/services-docker/neutron-sriov.yaml \
>   -e /usr/share/openstack-tripleo-heat-templates/environments/services-docker/neutron-ovs-dpdk.yaml
Not found image: docker://rhosp13/openstack-cinder-volume:latest
time="2018-09-05T22:02:12Z" level=fatal msg="Error reading manifest latest in docker.io/rhosp13/openstack-cinder-volume: errors:
denied: requested access to the resource is denied
unauthorized: authentication required>