An erroneous change in configuration has led to unavailability of the Kubernetes plugin responsible for managing persistent volumes (CSI). Interactive user sessions on renkulab.io are backed by persistent volumes. While the CSI plugin was unavailable, no new user sessions could be launched. As soon as the faulty configuration change was rolled back, services became fully functional again.
Improving the test coverage of the code base which encodes the underlying infrastructure on which the services of renkulab.io are running will help us prevent outages like this in the future.