Q: How do you implement SLO-based alerting without alert fatigue?
Implementing Google SRE multi-window multi-burn-rate alerting in Prometheus to eliminate noisy threshold alerts while detecting catastrophic service budget exhaustion.
#SRE #SLO #Prometheus #Burn Rate #Alerting #Google SRE
🎙️ Candidate Opening & Architectural Context
"Traditional alerts rely on static error rate thresholds (like Error Rate > 2% for 5 mins), which leads to alert fatigue during brief transient spikes and misses slow, insidious burns. The Google SRE solution is Multi-Window Multi-Burn-Rate alerting tied to Error Budgets."
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🛠️ Production Runbook & Step-by-Step Resolution
1
Define the Error Budget & Burn Rates
For a 99.9% availability SLO over 30 days, your error budget is 0.1% (43.2 minutes of total downtime). A 1x burn rate consumes 100% of the budget in exactly 30 days. A 14.4x burn rate consumes 2% of the budget in 1 hour.
2
Configure Multi-Window Strategy in Prometheus
To prevent false alarms, an alert requires BOTH a short window (to detect sudden onset) and a long window (to ensure the burn is sustained).
# Alert when consuming 2% of budget in 1 hour (14.4x burn rate)
expr: (
job:sli_error:burn_rate_1h > 14.4 and
job:sli_error:burn_rate_5m > 14.4
)
severity: page
# Alert when consuming 5% of budget in 6 hours (6x burn rate)
expr: (
job:sli_error:burn_rate_6h > 6 and
job:sli_error:burn_rate_30m > 6
)
severity: ticket
💡 The Senior SRE Gold Nugget (Key Architectural Takeaway)
"Multi-window burn-rate alerts page on budget exhaustion velocity, not arbitrary static thresholds. Pair short and long time windows to eradicate transient alert noise."
⚡ 60-Second Elevator Pitch Talking Points
- Tie alerting to SLO error budget consumption rather than arbitrary CPU or error percentage thresholds.
- Page on high burn rate (14.4x consumes 2% of monthly budget in 1 hour).
- File non-urgent tickets on slow burns (6x consumes 5% of budget in 6 hours).
- Combine short (5m) and long (1h) windows to prevent false alarms from temporary micro-spikes.
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