In redhat, if you need build container from base image, for example, registry.access.redhat.com/rhel7/rhel:7.3-53 (free download from https://access.redhat.com/containers) You have to build this image on a red hat server with subscription managed registered.
Here is the way to bypass the check and you can build docker image on any redhat 7 server.
yum install rh-amazon-rhui-client
$ rpm -ql rh-amazon-rhui-client
/etc/init.d/choose_repo
/etc/init.d/rh-cloud-firstboot
/etc/pki/rhui/cdn.redhat.com-chain.crt
/etc/pki/rhui/content-rhel7.key
/etc/pki/rhui/product/content-rhel7.crt
/etc/pki/rhui/product/rhui-client-config-server-7.crt
/etc/pki/rhui/rhui-client-config-server-7.key
/etc/yum.repos.d/redhat-rhui-client-config.repo
/etc/yum.repos.d/redhat-rhui.repo
/etc/yum.repos.d/rhui-load-balancers.conf
/etc/yum/pluginconf.d/amazon-id.conf
/etc/yum/pluginconf.d/rhui-lb.conf
/usr/lib/yum-plugins/amazon-id.py
/usr/lib/yum-plugins/amazon-id.pyc
/usr/lib/yum-plugins/amazon-id.pyo
/usr/lib/yum-plugins/rhui-lb.py
/usr/lib/yum-plugins/rhui-lb.pyc
/usr/lib/yum-plugins/rhui-lb.pyo
/usr/sbin/choose_repo.py
/usr/sbin/rh-cloud-firstboot.py
rpm -ql rh-amazon-rhui-client |tar cvf package.tar -T -
tar xvf package.tar
rm package.tar
FROM registry.access.redhat.com/rhel7/rhel:7.3-53
COPY etc /etc
COPY usr /usr
RUN yum -y update; yum clean all
docker build -t rhel7-base .
Now you still see below message, but yum update will continoue.
This system is not registered to Red Hat Subscription Management. You can use subscription-manager to register.
I tried this same to RHEL7 atomic minimal image but it cant resolve the rhui hostname. This image uses "microdnf" instead of "yum". I'm not sure how to provide credentials from host to the container.