Avoid having to add or change files in distribution
The subject states the more general aim which would make upgrades a breeze.
One of the remaining issues seems to be that overriding some of the stings or HTML templates requires adding files to
SWITCHwayf/www/css. That would have to be redone when unpacking a new release.
This could all be avoided by loading overriden files (by their original names) from an alternative location, ideally relative to
SWITCHWAYF_CONFIG. (This could work pretty even easier if SWITCHWAYF_CONFIG were a directory, not a file, like with SimpleSAMLphp's
Alternatively the path to overrides could be specificied within the config file in SWITCHWAYF_CONFIG itself, which would be compatible with keeping the environment variable reference a file.
#1 Updated by Peter Schober about 2 months ago
So instead of loading overrides from one specific location using one specific naming convention the main config file could supply an alternative location to load them from. That way you also wouldn't have to change the names from default-foo.php to custom-foo.php since they wouldn't be in the same directory and so wouldn't conflict.
I.e., keep software and configuration/overrides separate. (Think config and overrides in /etc/ and the rest living in a read-only /usr directory hierarchy. Same way Linux FHS and distribution packagers have been doing for years. Besides SimpleSAMLphp see also Filesender.)