The biggest areas I ran into manual merging issues where the custom data/snmp pollers and custom snmp-graphs. The ability to include a file into a unmodified opennms config file would solve these problems for me as I can keep my changes separate.

Created an attachment (id=1063)
Restore first script as it should not use etc-pristine

Ops, I did a mistake (tm). I cannot use etc-pristine. I must keep looking for .old files. I restored the first script

We have a number of "best practices" to avoid issues with upgrades, such as putting all new configs in their own separate packages, etc.

However, this script looks pretty cool.

RedHat-style systems often use both approaches (1) and (2) above. That is, where possible they extract the things generally set as local config changes or options into their own files (normally under /etc/sysconfig but the location doesn't matter) and they split optional/modular configuration components into *.d/ directories where each rpm can add its own snippet as needed without worrying much about what else is there. For opennms, I'd think approach (1) is the more important piece - separate the local/user config from the rpm-supplied defaults and let them override the defaults. That way updates can (nearly) always overwrite the unchanged default files while keeping local changes/additions. Approach (2) would be good for canned optional configuration settings, though.

Created an attachment (id=1061)
Script to fix config files after upgrade