Faultline: Open-Source Go Tool Tests Distributed System Consistency via Chaos Injection

A developer has released Faultline, an open-source Go-based testing harness that injects faults into distributed systems and checks whether observed operation histories satisfy linearizability, drawing on the methodology of Kyle Kingsbury's Jepsen project. The tool uses a four-method contract interface, allowing new targets to be integrated without modifying the core fault injector, workload generator, or checker. Faultline was validated against two architecturally distinct targets — a three-node etcd cluster and NATS JetStream's key-value store — with no consistency violations detected under tested conditions. The harness incorporates a Wing-Gong linearizability search with memoization and a bounded budget to avoid indefinite hangs on unresolvable histories. Notably, the development process itself surfaced six bugs within the harness, lending credibility to the tool's correctness-checking capabilities.