four golden signals
also: 4 golden signals, golden signals
Four key metrics—latency, traffic, errors, and saturation—used to monitor and measure the health and performance of systems and services in production environments.
The four golden signals are a framework for observability popularized by Google's Site Reliability Engineering (SRE) practices. They help operators quickly assess system health by focusing on the metrics that matter most.
Latency measures how long requests take to complete. Traffic measures the volume of requests hitting the system. Errors measure the rate of failed requests. Saturation measures how full or utilized the system is—for example, CPU usage, memory consumption, or disk I/O capacity.
Example: Monitoring a web server, you might track average response time (latency), requests per second (traffic), HTTP 5xx errors (errors), and CPU usage percentage (saturation). A sudden spike in errors combined with high saturation might indicate the server is overloaded.
These four signals form the foundation of alerting strategies and help teams avoid alert fatigue by focusing on high-impact metrics rather than monitoring everything.