Earlier today the server ran out of disk space during some routine deployments, which caused a cascade of issues: the database cache (Redis) couldn't save its data and started refusing writes, which took the entire game down.
I've freed up disk space, repaired the affected Redis instance, and everything's back up and running normally. No player data was lost. I'm adding some housekeeping to stop disk space from filling up like this again.
Sorry for the downtime — thanks for bearing with me.