Choosing SLIs: From User Journeys to Measurable Signals
A good SLI comes from the user's journey and is the ratio of good events to valid events; 4xx answers and health checks stay out of the denominator. For Bookstore's checkout we write availability and latency SLIs from ASP.NET Core's http.server.request.duration histogram and measure how mixing all endpoints and averaging hide errors, and why the application metric sees nothing while the API is down.
15 Nov 2026
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10 min
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8
