SLI

Problem

Everyone says: “The service should be reliable.” But what exactly does reliable mean? Availability? Latency? Successful requests?

Solution — Service Level Indicator

Choose a measurable indicator of user-visible service behaviour.

For example:
successful requests
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 total requests

Your team and product owners choose SLIs based on user needs, commonly success rate, response time, or data freshness. Define what counts as success and the measurement window. Current performance provides a baseline; the desired target is an SLO and depends on the service.

Core idea: an SLI turns an aspect of service reliability into something measurable.