Monitoring and Verification of Multitenant Kubernetes Clusters using TLA+ Trace Checking

Abstract

In distributed systems, model checking is usually used at design time for specifying an abstract model of the system and then exhaustively checking all possible behaviors. TLA+ is commonly used in this way as a specification language, together with the TLC model checker. In this paper, we present a monitoring tool that, at its core, utilizes TLA+ specifications in a different way. The tool utilizes a TLA+ trace-checking specification to detect violations in behavior inferred from Kubernetes audit logs. Our primary use case focuses on multitenancy violations; however, the pipeline is not limited to that setting. Specifically, it demonstrates how formal reasoning can be incorporated into live Kubernetes environments to improve monitoring and correctness checking.