Unable to install Imunify360 on CentOS getting errors from the `baseos` repo

Issue

Getting the following error during the attempts to install Imunify360:

Error: Failed to download metadata for repo 'baseos': Cannot prepare internal mirrorlist: No URLs in mirrorlist
Package imunify360-firewall was not installed.
...
Error: Failed to download metadata for repo 'baseos': Cannot download repomd.xml: Cannot download repodata/repomd.xml: All mirrors were tried
Package imunify360-firewall was not installed.

Environment

• Imunify360
• CentOS 8

Solution

• Consider fixing the operating system base repository because it's required by other software to pick up dependencies provided on the base. For example, the repository address can be changed from mirror.centos.org to vault.centos.org on server with EOL CentOS 8:

# cp -arvp /etc/yum.repos.d/ /etc/yum.repos.d.backup-before-sed
# sed -i -e "s|mirrorlist=|#mirrorlist=|g" /etc/yum.repos.d/CentOS-*
# sed -i -e "s|#baseurl=http://mirror.centos.org|baseurl=http://vault.centos.org|g" /etc/yum.repos.d/CentOS-*

• As an alternative, it can try to migrate to Almalinux, though the decision is up to the server administrator: https://almalinux.org/ 

Cause

As of January 31, 2022, the CentOS 8 mirror lists are offline, so it can't get the repomd.xml from there. Imunify360 or any other vendor software may require some package provided only from Centos OS Base repository, so if it can't pick up it won't be possible to install ones. 
 

Useful links

• https://github.com/AlmaLinux/almalinux-deploy