Troubleshooting Package Synchronization
Uyuni does not automatically trust third party GPG keys.
If package synchronization fails, it could be because of an untrusted GPG key.
You can find out if this is the case by opening
/var/log/rhn/reposync and looking for an error like this:
['/usr/bin/spacewalk-repo-sync', '--channel', 'sle-12-sp1-ga-desktop- nvidia-driver-x86_64', '--type', 'yum', '--non-interactive'] ChannelException: The GPG key for this repository is not part of the keyring. Please run spacewalk-repo-sync in interactive mode to import it.
To resolve the problem, you need to import the GPG key to Uyuni. For more on importing GPG keys, see Signing Repository Metadata.