I am trying to follow the first steps creating a red Hat based container as its in the documentation

but when I run

docker build -t rhel_httpd .

for my My cool Docker image, with exactly the docker file from the example / documentation, I get

There are no enabled repos.
 Run "yum repolist all" to see the repos you have.
 To enable Red Hat Subscription Management repositories:
     subscription-manager repos --enable <repo>
 To enable custom repositories:
     yum-config-manager --enable <repo>

I am on a red Hat Server, and my system has a subscription,
why do I get this problem?

Thanks for help!