SafeOps Academy

SLI/SLO Spec: Chapter 09 Baseline

Scope

Service in scope:

  • backend HTTP API

Environment scope:

  • develop, staging, production

Indicators (SLIs)

  1. Availability SLI
  • Definition: ratio of successful requests (non-5xx) to total requests.
  • PromQL:
1 - (
  sum(rate(app_http_requests_total{job="backend",status=~"5.."}[30m]))
  /
  clamp_min(sum(rate(app_http_requests_total{job="backend"}[30m])), 1e-9)
)
  1. Latency SLI (p95)
  • Definition: p95 backend request duration over rolling window.
  • PromQL:
histogram_quantile(0.95,
  sum(rate(app_http_request_duration_seconds_bucket{job="backend"}[5m])) by (le)
)

Objectives (SLOs)

  1. Availability SLO
  • Target: 99.5% over 30 days.
  • Error budget: 0.5%.
  1. Latency objective (operational target)
  • Target: p95 < 1s on 5-minute windows.
  • Used for warning/critical operational alerts.

Alert Strategy

  1. Immediate symptom alerts
  • BackendCriticalErrorRate
  • BackendHighLatency
  • BackendServiceDown
  1. Budget consumption alerts (burn-rate)
  • BackendSLOErrorBudgetBurnCritical: fast burn on 5m and 1h windows (14.4x budget).
  • BackendSLOErrorBudgetBurnWarning: sustained burn on 30m and 1h windows (6x budget).

Guardrails

  • Do not page only on single-point spikes without cross-signal evidence.
  • For customer-impact decisions, require: metrics symptom + one representative trace + correlated log line.
  • Every alert route must include runbook: runbook-incident-debug.md.