CentOS Linux 8 is EOL, attempting to install packages in it results in
an error. CentOS Linux is a rebuild of RHEL (stable versions). The
CentOS projects recommends to use CentOS Stream instead, which is a
build of the "public development branch for RHEL".
After the early EOL was announced on 2020-12-08, alternative projects
AlmaLinux and Rocky Linux have been established as binary compatible
forks of RHEL 8 (stable versions).
Both Alma and Rocky seem to be solid projects, see related Wikipedia
articles and their sources. Pick Alma and adjust the whole tree to use
the almalinux:8 docker image instead of centos:centos8.
Error: Failed to download metadata for repo 'appstream': Cannot download repomd.xml: Cannot download repodata/repomd.xml: All mirrors were tried