slo-alerting

name	slo-alerting
description	Define SLIs, SLOs, and implement burn-rate alerting
triggers	["SLO definition","SLI metrics","error budget","burn rate alerting"]
priority	2

SLO Alerting

Define SLIs, set SLO targets, alert on burn rate (not raw error rate).

Concepts

Term	Definition	Example
SLI	Quantitative measure	% successful requests
SLO	Target for SLI	99.9% success
Error Budget	Allowed failure	0.1% = 43 min/month
Burn Rate	Budget consumption speed	10x = exhausted in 3 days

Common SLIs

Availability: successful_requests / total_requests
Latency:      requests_under_threshold / total_requests
Error Rate:   error_requests / total_requests

Burn Rate Alerting

Alert on how fast you're consuming budget, not raw error rate:

Alert Level	Burn Rate	Time to Exhaust
Page (critical)	14.4x	2 days
Page (warning)	6x	5 days
Ticket (medium)	3x	10 days

Multi-Window Strategy

Use long + short windows to balance speed and noise:

# Critical: Fast burn (14.4x over 1h AND 5m)
- alert: HighBurnRate_Critical
  expr: (rate_1h / budget > 14.4) and (rate_5m / budget > 14.4)
  severity: critical

# Warning: Slower burn (6x over 6h AND 30m)
- alert: HighBurnRate_Warning
  expr: (rate_6h / budget > 6) and (rate_30m / budget > 6)
  severity: warning

Dashboard Essentials

• Current burn rate
• Error budget remaining (%)
• Time until exhaustion at current rate

Anti-Patterns

• Too many SLOs → SLO per user journey, not per endpoint
• Alerting on raw error rate → Noisy, doesn't account for budget
• No budget visualization → Teams don't understand burn rate

References

• references/methodology/sli-slo-framework.md