Execution pipeline service degradation on EU-WEST-2

At approximately 7:00AM Arizona the Prismatic team received several alert notifications for failed executions. Upon investigation it was discovered that a very large volume of executions had started, and autoscaling was not configured with a high enough upper threshold to accommodate. The Prismatic team took action to raise the thresholds and align them with other high-volume stacks, and service was fully restored by 7:20AM Arizona. We will audit and address any similar situations we discover on other high-volume stacks.