The paws cluster uses the upstream recommended storage driver for docker (overlay2), which requires the overlay filesystem to be enabled on the node. The overlay kernel module is blacklisted in puppet however, and seems to be inconsistently applied - loadable sometimes and not others. This has caused several outages already.
Would be great if it could be removed from the blacklist on toolforge.
https://docs.docker.com/engine/userguide/storagedriver/overlayfs-driver/
https://www.coshx.com/blog/2016/06/16/wheres-my-overlay/