The Labs instance maps-tiles1.maps.eqiad.wmflabs is running Ubuntu Precise. It needs to be deleted, replaced, or upgraded in place. (The latter is a bit risky but I think @dschwen already has a record of success there.)
I personally am not using this instance. It might be in use live for the OSM gadget on the german Wikipedia (does https://tiles.wmflabs.org/ point to that machine?)
If nobody else steps up I could try to log in and see if do-release-upgrade works there, too (it did for my instances). This will most likely require a rebuild of the map stack on that machine, though. But if the machine is lost otherwise it might just be worth the risk.
(copy of my email reply to Andrerw et al.)
Ok, there is an apache2 with modtile, a renderd, and a (small 34MB)_ postgres 9.1 database running on there.
modtile and renderd are installed from http://ppa.launchpad.net/kakrueger/osm-unstable/ubuntu/
For modtile and renderd there are trusty packages on that PPA.
Looking closer at the apache2 config it looks liek this is a debug/experimental server
ServerName tile.mytileserver.org ServerAlias a.tile.mytileserver.org b.tile.mytileserver.org c.tile.mytileserver.org
logs are pretty much empty (despite log level _info_)
not aware of this being used though not entirely sure. I think it was experimental at one point before we had production maps support.
not sure if anything on German Wikipedia uses this. I do see https://tools.wmflabs.org/geohack/geohack.php?pagename=Freiburg_im_Breisgau&language=de¶ms=47.994828_N_7.849881_E_region:DE-BW_type:city(226393) uses tiles.wmflabs.org but that might be different labs instances. Anyway, it would be easy enough to change to use production map tiles.
tiles.wmflabs.org is served by the instance maps-tiles3 in the project maps:
sqlite> SELECT project.name, url FROM backend JOIN route ON route_id = route.id JOIN project ON project_id = project.id WHERE domain = 'tiles.wmflabs.org.'; maps|http://maps-tiles3.eqiad.wmflabs:80 sqlite>