cyber-dojo donations going to buy Raspberry Pies for schools. It caused a big surge of use on the site :-) Which unfortunately brought the site down :-(
At first I thought the 'No space left on device' message meant I'd run out of disk space.
However a df revealed plenty of 1K blocks still available.
The problem was not lack of disk space it was lack of inodes!
This is because
cyber-dojo uses a lot of files (every press of the run-the-tests button results in a git commit).
I put a temporary fix in place by recovering a few thousand inodes. That gave me enough time to put a better fix in place - some scripts to zip and prune dojos based on both their age and total number of traffic-lights. Successive prunings reclaimed 231,941 inodes which should last a while.
Sorry for the glitch.