An SLI, or Service Level Indicator, is the actual metric used to measure whether a service is meeting its reliability objectives. Common SLIs include availability (percentage of successful requests), latency (response time at a given percentile), and error rate (percentage of failed requests).
SLIs are the foundation of the SLA/SLO/SLI framework. The SLI provides the measurement, the SLO sets the target, and the SLA is the external commitment. Without accurate SLI data, teams cannot meaningfully track or report on their reliability.
Good SLIs are chosen from the user's perspective. Rather than measuring CPU usage or disk space (which are internal metrics), effective SLIs measure what the user experiences: "Did the page load successfully?" and "How long did it take?" Hyperping's uptime and response time monitoring provides SLI data directly aligned with user experience.
