CentOS 8 builds failing

[sbesson]

See https://github.com/ome/omero-install/actions/runs/1800964267

The CentOS 8 build started failing with

  ---> Running in d4db2db7f186
CentOS Linux 8 - AppStream                      184  B/s |  38  B     00:00    
Failed to set locale, defaulting to C.UTF-8
Error: Failed to download metadata for repo 'appstream': Cannot prepare internal mirrorlist: No URLs in mirrorlist
The command '/bin/sh -c yum install -y langpacks-en glibc-all-langpacks' returned a non-zero code: 1

This is related to https://www.centos.org/centos-linux-eol/ and has hit other projects lately - see https://flutterq.com/failed-to-download-metadata-for-repo-appstream-cannot-prepare-internal-mirrorlist-no-urls-in-mirrorlist/, https://techglimpse.com/failed-metadata-repo-appstream-centos-8/, https://forums.centos.org/viewtopic.php?f=54&t=78708.

[jburel]

I think we should remove it completely.

[sbesson]

Looking at our usage of CentOS 8 across the project, it is also used in a handful of places like https://github.com/ome/ansible-role-ice used it for testing.

Probably the question with the biggest impact for our community is whether the installation walkthroughs should be retired from the documentation as well https://docs.openmicroscopy.org/omero/5.6.3/sysadmins/unix/server-centos8-ice36.html and https://docs.openmicroscopy.org/omero/5.6.3/sysadmins/unix/install-web/walkthrough/omeroweb-install-centos8-ice3.6.html?

[jburel]

if it is removed from this repo and omeroweb repo, the documentation won't be generated so any entry will have to be removed.
We could get it to work but I am not convinced it is required due to EOL

[sbesson]

I am pretty certain I was not keen on adding CentOS 8 to the supported list in the first place. So no objection to dropping it from my side. We will need to manage the expectations similarly to what we have done with Ubuntu 18.04.