Official RH Containers
Redhat offers containers in an sub based model or a UBI model. Sub based requires a subscription to update though this is taken care of seamlessly when ran from a licensed RHEL host.
Universal Base Image
The universal base image is explained in the RH docs and can be found in the docker hub.
It does NOT require a subscription to use.
UBI can be explored in the search here
This is also the only way to get UBI7, it is not in docker hub
7.3. Adding software to a UBI container on a subscribed host
- https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/8/html/building_running_and_managing_containers/assembly_adding-software-to-a-ubi-container_building-running-and-managing-containers
- https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/8/html-single/building_running_and_managing_containers/index#con_adding-software-to-a-ubi-container-on-a-subscribed-host_assembly_adding-software-to-a-ubi-container
If you are running a UBI container on a registered and subscribed RHEL host, the RHEL Base and AppStream repositories are enabled inside the standard UBI container, along with all the UBI repositories.
Installing Red Hat packages that are not inside the Red Hat UBI repositories can limit the ability to distribute the container outside of subscribed RHEL systems.
This does not say you are not permitted to do it, just that things may break
If Subscription manager is not handling your repos, UBI will not add them. subscription-manager repos --list should provide valid output. If disabled it will say "Repositories disabled by configuration"
Enabling or disabling a repository using Red Hat Subscription Management - Red Hat Customer Portal
UBI Licensing
EULA_Red_Hat_Universal_Base_Image_English_20190422.pdf (redhat.com)
Universal Base Images FAQ | Red Hat Developer
Red Hat simplifies container development and redistribution of Red Hat Enterprise Linux packages | Red Hat Developer