Why SLOs Break in Microservices

A SLO that works for a monolith often collapses when you distribute the same logic across 30 services. The math of availability is unforgiving.

If your service depends on 5 others, each at 99.9%, your realistic ceiling is 0.999^5 = 99.5% . That 0.4% gap eats your entire error budget before your own code even runs.

The Three Mistakes Teams Make

1. Copying the same SLO to every service

A 99.9% target on a payment service and a batch analytics service are not the same thing. One ruins revenue. One ruins dashboards.

2. Measuring uptime instead of user experience

GET /health returning 200 is not a SLO. Users don't call /health . They check out, log in, view pages. Measure those.

3.…