Cloud-Scale Runtime Verification of Serverless Applications

Serverless platforms aim to simplify the deployment, scaling, and management of cloud applications. Serverless applications are inherently distributed, and are executed using shortlived ephemeral processes. The use of short-lived ephemeral processes simplifies application scaling and management, but also means that existing approaches to monitoring distributed systems and detecting bugs cannot be applied to serverless applications. In this paperwe proposeWatchtower, a framework that enables runtime monitoring of serverless applications. Watchtower takes program properties as inputs, and can detect cases where applications violate these properties. We designWatchtower to minimize application changes, and to scale at the same rate as the application. We achieve the former by instrumenting libraries rather than application code, and the latter by structuringWatchtower as a serverless application. Once a bug is found, developers can use theWatchtower debugger to identify and address the root cause of the bug.