The Error Budget Playbook That Stops Tier‑0 Fires Before They Start
Design error budget allocation by service tier, watch leading indicators that actually predict incidents, and wire telemetry into your triage and rollout automation so you ship faster without burning trust.
Error budget is the only currency engineers and executives both understand — spend it where it buys the most learning, never where it risks the most trust.Back to all posts
Key takeaways
- Tie error budgets to service tiers and blast radius, not org charts or politics.
- Use leading indicators like queue depth, tail-latency slope, retry storms, and resource saturation to predict incidents.
- Label everything with service tier; make SLOs, dashboards, alerts, and runbooks tier-aware.
- Gate rollouts with SLO burn and leading-indicator checks using Argo Rollouts or Flagger.
- Allocate budget explicitly across deployment, dependency, and experiment buckets; automate the ledger.
- Run weekly budget reviews and freeze policies per tier; make reversibility and time-to-rollback first-class KPIs.
Implementation checklist
- Define 3-4 service tiers based on blast radius and recovery options.
- Set per-tier availability SLOs and monthly budgets that match business risk.
- Instrument leading indicators and compute burn rates with multi-window alerts.
- Label services with tier in code, CI, and infra (Kubernetes, PagerDuty, Datadog).
- Gate progressive delivery with SLO burn and leading indicators.
- Create a budget ledger and freeze policy automation.
- Review budgets weekly; prioritize toil burn-down and rollback time reductions.
Questions we hear from teams
- How many service tiers is ideal?
- Three to four. More than four becomes theater. We typically use Tier 0 (trust/wallet), Tier 1 (critical), Tier 2 (supporting), Tier 3 (non-critical/experiments).
- Should error budgets include planned maintenance?
- Yes, but categorize it. If you can shift maintenance to reduce customer impact (blue-green, shadow traffic), do it. Planned burn is still burn — it trades reliability for change. Make it explicit in the ledger.
- What if dependencies burn our budget?
- Track dependency-caused burn separately. Use circuit breakers, timeouts, and backpressure so your Tier 0 doesn’t mirror an upstream blast. Push vendors with data and adjust objectives if reality disagrees with marketing.
- We’re all microservices. Do I need SLOs per service?
- Per tier and per critical path. Don’t boil the ocean. Start with Tier 0 services in the customer critical path, then add Tier 1. Aggregate supporting Tier 2/3 into shared SLOs until you have signal.
- Can AI-assisted development help or hurt this?
- Both. AI can accelerate delivery, but it also introduces subtle failure modes (retry loops, N+1 queries, unsafe timeouts). Your leading indicators and rollout gates are the safety net that catches AI hallucination before customers do.
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