Composite Alarms
Explore how composite alarms enhance AWS monitoring by merging multiple alarm signals into one clear alert. Understand their logic types, validation methods, and best practices to minimize false paging while maintaining system observability and reliability.
A paging policy often contains a constraint that conflicts with naive thresholds: don't page for a single flaky instance, but do page when customer impact is likely. Alarming on every per-instance CPU spike or every single 5xx blip creates noise, meaning pages that don't lead to any action that actually changes system state.
Blind spots look different from noise, and they're the opposite of failure. A blind spot is a customer impact that fails to produce a page, because the alert design simply can't represent the decision that should trigger it. Composite alarms address that gap by combining the states of existing alarms into one actionable signal, though they don't create new metrics, and they don't make missing instrumentation disappear.
From resource alarms to an operator decision
The key design step is to separate detection from paging. Per-target, per-AZ, or per-service alarms detect local symptoms ...