Hi! As many of you know, a central global repository for Lua modules and
templates has been a frequent request since the early days of the movement.
This year, I programmed a JavaScript tool called Synchronizer
https://www.mediawiki.org/wiki/Synchronizer
(inspired on a previous tool called DiBabel by User:Yurik)
The tool allows to synchronize (that is, automatically copy) Lua modules
across Wikimedia wikis, and provides other features to help developers
update and maintain global modules.
I also re-wrote the documentation at
https://www.mediawiki.org/wiki/Multilingual_Templates_and_Modules to
account for the new tool. It basically describes how to develop a Lua
module that can be copied unchanged to any wiki, by abstracting things like
user-readable strings and config.
Admittedly, this is a "poor man's version" of a proper solution to the
problem, but one I find invaluable while developing and maintaining
modules. Hopefully some of you may find it useful too!