SLI Specification
Illustrative rows for a fictional grocery delivery company, Ashgrove.
| Service | Indicator | Target, as written | Where it was written | Trailing 90d | Class | Rewritten as |
|---|---|---|---|---|---|---|
| Checkout | Request success | 99.9% | runbooks/checkout.md, line 4 | 99.94% | enforceable | no change needed |
| Checkout | Request success | 99.99% | 2026 renewal deck, slide 11 | 99.94% | aspirational | tracked, no policy attached |
| Catalogue search | Request latency, p99 | p99 under 800ms | Grafana panel title | reads exactly 500ms, every day | not measurable | 99.0% of searches faster than 250ms |
| Driver app API | Request latency, p95 | p95 under 300ms | platform wiki, Reliability page | 210ms over 61% of traffic | not measurable | 99.0% faster than 300ms, counted at the gateway |
| Order tracking | Data freshness | near real time | help centre article, published | 99.2% under 30s old | enforceable after rewrite | 99.0% of reads under 30 seconds old |
| Payments gateway | Host uptime | 99.95% uptime | vendor status page, in our contract | 99.97% theirs, 99.71% ours | measures the wrong thing | 99.5% of authorisations decided within 3s |
| Catalogue search | Request success | 99.5% agreement, 99.9% dashboard | master agreement sch. 2, and the dashboard | 99.87% | conflicting | one target chosen, the other recorded as the floor |
| Nightly settlement | Output correctness | none written anywhere | nowhere | not instrumented | not measurable | proportion of seeded records producing the expected output |
Three columns where most registers carry one. The transcription, the measurement, and how the two relate. A register with only a target column is asserting; the middle column is what makes a wrong promise findable before a customer finds it.
Row two is the same indicator as row one. Both numbers are written down, one of them in front of an enterprise customer, and trailing attainment misses it by a factor of six. Adopting it means permanent breach, so it is measured and excluded from the policy by name.
Of eight written targets, one is ready to carry a policy today. That ratio is normal on a first pass.