On 21 January 2019 between 10:52am (UTC) and 11:10am (UTC) customers hosted in the EU Pod experienced a number of failed requests for static assets resulting in broken themes (due to missing CSS, JS and images).
Investigation and Root Cause
Upon investigation, Engineers identified that 6 (out of 12) servers had come into the rotation and failed to map to the underlying asset store. Typically new servers come into rotation every 6 hours as part of the automatic scaling nature of the Interact application.
Interact believes that a recent update of our APM (Application Performance Monitoring) agent may have been responsible for the issue, however pre-release testing and subsequent investigations have proved inconclusive. Interact responded to the issue by forcing a rotation of new hardware.
Resolution and Mitigation Steps
Subsequent to the issue, Interact has updated its automatic deployment process to attempt the remap to the underlying asset store a minimum of 5 times if a failure of mapping occurs.