Intiial test setup has been created.
Currently there are two wikis:

• http://mainrepo-federation-wikis.wmflabs.org hosts a Wkibase repository - could be seen as a fake "Wikidata" in the test
• http://mediainfo-repo-federation.wmflabs.org hosts an own Wikibase repo but is also using properties from the "mainrepo" (using repository/interwiki "main") - could be seen as "Commons" in the test

I still need and want to improve the way puppet is involved in creating the setup, and also improve configuration of test wikis (WikibaseMediaInfo extension should be installed, interwiki/sites setup etc).
Also I'd like to have a client (without a repo) set up there, so client-only functions can be tested as well.

Please do not consider this ticket as done. I've just started.

I've changed the setup slightly, and the initial test system can be considered established in my opinion.

Labs project for testing federation features is wikidata-federation.
There is an instance in this project hosting test wikis, called federation-wikis (should probably have been "federated-wikis" to sound less odd but realized that too late).
On this instance three wikis have been created, and exposed to the world:

• http://mainrepo-federated-wikis.wmflabs.org - a Wikibase Repo instance providing items and properties.
• http://mediainforepo-federated-wikis.wmflabs.org - a Wikibase Repo instance providing media info entities. This repo is configured so it uses items and properties from the other repo.
• http://clientone-federated-wikis.wmflabs.org - Wikibase instance is running there with only Client component enabled. This is not something we really planned but I thought it might make sense. Exact configuration of this wiki (what repos should it use? main? both?) etc is to be decided once we move on with testing

Currently configuration of those wikis is very basic, and there is no much content in there.

Wikis have been set up in a rather hacky manner to get the test system running. As I am rather mediocre with puppet and vagrant, I still haven't created nice puppet rules to install Wikibase with desired components, extensions etc. While I still think it is worth effort and I want to do it, I just didn't have enough time to do it now. I believe we would benefit by having a simple way to just say "I want 3 wikis, one repo with X, other repo with Y, and a client", as we could use when setting up a test system for "structred commons", as well as "structed lexicographic data", and even for developer's own environment. That said I think creating those puppet/vagrant stuff should not be blocking this task. Therefore I leave the rather manual setup of "federated-wikis" wikis as it is now, and will track the puppet work separately (not as a part of Wikidata sprint). To track this I've filed T159924.