For a weeks, we have noticed CI agents being disconnected due to /srv being full. @dancy added a collect of the jobs workspace disk consumption on all the agents which are stored in Graphite ( 6555facef5bdfb6817e9889cf1ce6b4a48005824 T258626 ).
The top offenders can be seen at https://graphite.wikimedia.org/S/p which leads to Quibble selenium jobs. They run npm install for each extensions/skins and fill up the patch. @dancy found out that XDG_CACHE_HOME get filed with directory named lighthouse.XXXX which keeps piling up.
We need to find what that lighthouse system is and have it either stop caching or no more vary the cache directory name.