Universal Base Images (UBI) details can be found for example in https://developers.redhat.com/blog/2019/05/31/working-with-red-hat-enterprise-linux-universal-base-images-ubi/
UBI8 images details as of 2019-06-05
docker images | grep ubi
registry.access.redhat.com/ubi8/ubi latest 4a0518848c7a 5 weeks ago 208MB
registry.access.redhat.com/ubi8/ubi-minimal latest 3bfa511b67f8 5 weeks ago 90MB
docker run -i -t registry.access.redhat.com/ubi8/ubi bash
dnf search fooBarBaz
docker run -i -t registry.access.redhat.com/ubi8/ubi-minimal bash
dnf search fooBarBaz
bash: dnf: command not found
microdnf --nodocs -y install zlib-devel && microdnf clean all
microdnf doesn't support search so I had second terminal with full UBI8 image running and did search using classical dnf.