Service level objective

A target tied to a measurement

An SLO might state that 99.9% of valid requests should succeed during a calendar month, or that 95% of requests should return within 300 milliseconds. The target is meaningful only when the corresponding SLI, time window, and exclusions are clear.

Set a target people can use

An illustrative API team chooses a latency objective based on what users notice and what the service can reliably provide. A target that is too loose may fail to prompt useful investment. A target that is impossibly strict can encourage teams to ignore it or spend resources without improving the experience.

The objective is a decision aid. It helps a team balance reliability work with feature work and understand when an error budget is being consumed.

Interpret a miss in context

Missing an SLO does not automatically identify the cause. A deployment, dependency outage, capacity limit, or measurement problem may be involved. Check the evidence and the user impact.

Avoid turning an SLO into an individual performance target. Reliability is a property of a system, and the work needed to improve it often crosses team boundaries. Review the target as the service and its users change.