docker pull certification error

export DOMAIN_NAME=<my-dtr-domain>

    echo -n | openssl s_client -showcerts -connect itapregistry.a1.vary.redhat.com:443 2>/dev/null |sed -ne '/-BEGIN CERTIFICATE-/,/-END CERTIFICATE-/p' >> /etc/pki/ca-trust/source/anchors/$DOMAIN_NAME.crt

update-ca-trust
/bin/systemctl restart docker.service