This is a meta-task for a series of things we need to do in order not to accumulate further technical debt on the appservers.
In short, the following things need to be taken care of:
- Upgrade libicu so that we can use the system-provided one
- Drop all references to zend-specific configs in the mediawiki classes, wherever they're not needed
- Make mediawiki classes compatible with Debian Jessie
- Reduce the app layer clusters to appropriate sizes
- Upgrade the appservers to jessie
- Profile and improve the puppet execution time for the role::mediawiki::* classes