Why do I have CUPS on my cluster? I don't want CUPS opening up ports or trying to print! I don't even have a printer attached to my cluster!
Part of the LSB (Linux Standard Base) specification requires that printer interfaces exist, even if they are not to be used. These interfaces are provided by CUPS, which is why some printer packages are dependencies of the LSB-related packages. If the CUPS packages are removed, then the basic LSB package must also be removed, which means that further updates may not be LSB-compliant. The best practice for staying LSB-compliant and still having the interfaces, without running CUPS, is to install the required CUPS packages and to have CUPS disabled.
On Red Hat based systems CUPS is installed, but disabled by default by Bright Cluster Manager on the head and regular nodes.
On a SLES Bright Cluster Manager installation, CUPS is not installed by default.
CUPS can be enabled by installing it if required (for example, in the case of a default SLES Bright Cluster Manager installation), and then adding it as a service (section 4.10.2 of the Adminstrator Manual).