What gets computed
For each affected SLO:- Burn during incident: the seconds the SLO counted as bad
during the incident, exactly as its error budget counts them:
unhealthy time, plus (under the default
downunknown-data policy) no-data time and silent gaps. Excluded maintenance is left out. The incident runs from its actual start (else when it was published) to its actual end (else when it was resolved, else now). A canceled incident shows no duration. - Percent of budget consumed: burn seconds divided by the SLO’s total budget seconds. Total budget = window seconds × (1 − target%).
- Total budget remaining: the last-computed budget percentage from the periodic evaluator, not recomputed in the panel. It may be a few minutes stale.
- Time to exhaust: at the current burn rate (burn seconds / incident duration seconds), how long until the remaining budget reaches zero. Reported in minutes; null when the burn rate is zero.
Caching
Repeated panel polls within 30 seconds reuse the same computation (in-memory cache keyed by incident id). This keeps an open dashboard that polls every 30s from triggering redundant recomputation.Sources of error
- Recorded metric history is the source of truth for burn. Missed pushes count only as the SLO’s unknown-data policy says, and only for agents on version 1.4.0 or later.
- The remaining-budget % comes from the most recent run of the periodic evaluator. If evaluation fell behind, the value can be stale by a few minutes. The burn-during-incident value is always fresh.
- Time-to-exhaust extrapolates a linear burn rate. Real systems rarely sustain a linear rate; treat the number as a rough budget rather than a precise countdown.