Postmortem playbook for Cloudflare/AWS-style outages

When Cloudflare or AWS goes dark: a practical postmortem playbook for CDN and cloud outages

Hook: You deploy frequently, your CI/CD pipelines are automated, and your SLA promises are public — but a CDN or cloud provider outage still brings your app to its knees. In 2026, with more logic at the edge and heavy reliance on managed services, a single provider incident can cascade quickly. This playbook gives engineering, SRE, and incident response (IR) teams a reusable template — detection, communications, root cause analysis, and preventative actions — specifically tailored to outages that originate from CDNs or public cloud dependencies.

Executive summary — what this playbook delivers (read first)

Fast, repeatable incident response saves revenue and reputation. This guide gives you:

• A compact, copy-pasteable incident response checklist for CDN/cloud outages.
• An auditable postmortem template that your CTO and compliance teams can sign off on.
• Concrete, actionable runbook snippets (monitoring rules, failover configs, communication templates).
• Prevention strategies tuned for 2026 trends: multi-CDN, OpenTelemetry-first observability, AI-augmented runbooks and tooling.

Why this matters now (2026 context)

Late 2025 and early 2026 saw a spike in multi-provider incidents and increased public scrutiny when major CDNs and hyperscalers reported regional degradations. Two trends change the stakes:

• Edge-first architectures put more customer-facing logic at CDN points of presence — making CDN outages directly user-impactful.
• OpenTelemetry ubiquity and AI-assisted runbooks mean teams can detect and diagnose faster — but only if they standardize data and workflows.

Those trends make it essential for teams to adopt a postmortem discipline tuned to cloud and CDN failure modes.

Incident taxonomy: classify early, act accordingly

Apply a simple severity matrix tailored to CDN/cloud dependencies. Use this upfront to route communications and escalation.

• Sev0 (Catastrophic) — Global outage or business-critical loss of traffic >80% impacting customers/revenue. Exec notification and incident war room required.
• Sev1 (Major) — Regional CDN/cloud provider outage causing degraded responses (>30% error rate) to production traffic. SRE lead and primary on-call required.
• Sev2 (Moderate) — Localized impact, degraded performance for a subset of regions/endpoints. On-call manages with normal channels.
• Sev3 (Minor) — Low impact anomalies, increased error rates in a non-critical path; document and observe.

Immediate response checklist (first 0–30 minutes)

1. Detect
   • Confirm with synthetic checks and real-user monitoring (RUM). Prioritize SLO violations and synthetic failures over single noisy alerts.
   • Correlate provider status pages (Cloudflare, AWS) and third-party outage aggregators to determine scope.
2. Assess scope
   • Map affected endpoints, regions, and customer segments. Use traffic tags and request traces to quantify impact.
3. Mitigate
   • Apply pre-approved failover: enable secondary CDN or switch Route 53 failover policies if configured.
   • Throttle non-essential traffic (analytics, batch jobs), preserve core user flows.
4. Communicate
   • Open an incident channel (Slack/Teams) and a public status message. Use the communication template below.
5. Document
   • Create an incident record in your IR tool (PagerDuty, Incident.io, or a shared doc). Timestamp actions and owners.

Quick detection rules (copy/paste examples)

Prometheus alert example for backend 5xx spike:

alert: BackendHigh5xxRate
expr: sum(rate(http_requests_total{job="edge" ,status=~"5.."}[5m])) / sum(rate(http_requests_total{job="edge"}[5m])) > 0.05
for: 2m
labels:
  severity: page
annotations:
  summary: "Edge 5xx rate >5%"
  description: "High 5xx errors observed at edge. Potential CDN or origin issue."

CloudWatch alarm for CloudFront origin failure count:

aws cloudwatch put-metric-alarm --alarm-name "CloudFront-Origin-Errors" --metric-name 5xxErrorRate --namespace "AWS/CloudFront" --statistic Average --period 60 --evaluation-periods 2 --threshold 0.05 --comparison-operator GreaterThanThreshold --dimensions Name=DistributionId,Value=E12345

Communication plan — internal and external

Communication is as important as mitigation. Keep messaging consistent, frequent, and role-specific.

Internal updates

• 0–15 minutes: Triage update (one-line summary, severity, owner, immediate mitigation).
• Every 15–30 minutes: Status updates in incident channel: actions taken, next steps, estimated next update time.
• Exec briefing: For Sev0/Sev1, provide a rolling 30-minute summary to CTO/Head of Ops and customer success leaders.

External updates

Post frequent, factual updates on your status page and social channels. Use a short template:

We are aware of an issue affecting [regions/endpoints]. Our engineers are investigating with our CDN/cloud provider. Users may experience elevated errors or latency. Next update: in 30 minutes.

Always close incidents with a post-incident update: cause (when known), impact summary, and ETA for the postmortem.

Root cause analysis (RCA) framework

The goal is to find the contributing causes and identify preventive actions — not to assign blame. Use a structured sequence:

1. Gather authoritative data
   • Collect provider status logs, internal logs, traces, and synthetic check histories.
2. Construct a timeline
   • Record handoffs, commands, deploys, config changes, and provider incident timestamps. Keep it minute-level for the critical window.
3. Identify direct cause(s)
   • Was it a provider configuration change, BGP/peering disruption, an edge rule that misfired, or an origin scaling problem?
4. Identify systemic contributors
   • Examples: lack of multi-CDN failover, TTLs too high, missing SLOs, or noisy alerting hiding the true early warning.
5. Recommend and schedule corrective actions
   • Each action needs an owner, priority, and verification plan.

Sample postmortem template (paste and use)

{
  "title": "[YYYY-MM-DD] CDN/Cloud Outage — short description",
  "severity": "Sev1",
  "start_time": "2026-01-16T10:22:00Z",
  "end_time": "2026-01-16T11:40:00Z",
  "impact_summary": "% of requests failed, regions affected, customer segments",
  "timeline": [
    {"time": "2026-01-16T10:22:00Z", "event": "Synthetic checks fail: US-East"},
    {"time": "2026-01-16T10:24:00Z", "event": "Triage: on-call SRE acknowledges"},
    ...
  ],
  "root_cause": "Direct cause (e.g., Cloudfront origin config change)",
  "contributing_factors": ["High TTLs", "No multi-CDN failover"],
  "actions": [
    {"action": "Implement Route53 failover policy", "owner": "alice@example.com", "due": "2026-02-10", "verification": "Failover simulation"}
  ],
  "lessons_learned": "Blameless summary and SOP updates",
  "attachments": ["logs.tar.gz", "provider-status-links"]
}

Preventative and long-term actions — prioritized

After the incident, convert root cause items into a prioritized remediation backlog. Typical actions for CDN/cloud outages:

• Multi-CDN with health-orchestrated failover

  Implement active-active or active-passive multi-CDN with a control plane that reroutes on provider health signals. In 2026, managed multi-CDN orchestration solutions have matured; evaluate them against custom Route 53 + BGP-based strategies. See regional and edge economics in Micro‑Regions & the New Economics of Edge‑First Hosting.

• Low TTLs and safer DNS practices

  Reduce TTL for critical records where failover is required; ensure DNS change windows and automated rollbacks are tested.

• Synthetic and RUM coverage mapped to SLOs

  Define SLOs for edge-dependent flows and instrument synthetic tests that mirror high-value user journeys. Use OpenTelemetry to standardize traces across edge and origin.

• Runbook automation and chaos testing

  Automate failover rehearsals and runbook steps (DR playbooks). Adopt light-weight chaos tests that simulate CDN failure modes in staging and pre-prod.

• Alerting hygiene

  Adjust thresholds to surface early, high-confidence signals. Use AI-based alert deduplication available in leading observability tools (2026 trend) to reduce noise.

• Compliance and auditability

  For regulated customers, capture incident artifacts and timelines in immutable storage (WORM) and map to applicable compliance controls. Consider storage and analytics patterns from ClickHouse guides like ClickHouse for scraped data for high-volume retention strategies.

Runbook snippets — failover, throttling, and quick remediation

Route 53 simple failover (pattern)

# AWS Route 53: create health checks and failover routing to a secondary origin
resource "aws_route53_health_check" "origin_primary" {
  // configuration for checking primary origin
}
resource "aws_route53_record" "app" {
  zone_id = var.zone_id
  name    = "app.example.com"
  type    = "A"
  alias {
    name                   = aws_cloudfront_distribution.primary.domain_name
    zone_id                = aws_cloudfront_distribution.primary.hosted_zone_id
    evaluate_target_health = true
  }
  set_identifier = "primary"
  health_check_id = aws_route53_health_check.origin_primary.id
  ttl = 60
}

Edge traffic throttling (example)

# Example pseudocode: reduce non-critical API rate by 80%
if incident.severity >= 1:
  set_rate_limit(api="analytics", rate=0.2)
  set_rate_limit(api="bulk_upload", rate=0.1)

Verification and regression testing

Every corrective action needs a verification plan:

• Run synthetic failover validation: simulate CDN 5xx responses and monitor automatic failover.
• Perform traffic cutover drills during a maintenance window and validate metrics and client behavior.
• Validate alerting changes with backfill and smoke tests to avoid regressions.

Blameless culture and legal/compliance considerations

Make postmortems blameless and evidence-driven. For incidents that affect customers or regulatory reporting, include legal and compliance early in the postmortem approval flow. Keep records for the retention periods required by GDPR, SOC 2, or other applicable frameworks.

Measuring success — metrics to track post-incident

• Mean Time to Detect (MTTD) — improved by synthetic coverage and unified traces.
• Mean Time to Mitigate (MTTM) — capture how fast mitigations like failover were applied.
• Mean Time to Recover (MTTR) — time until normal operations resume.
• Post-incident action completion rate — percent of RCA actions implemented on time.

Advanced strategies for 2026 and beyond

Adopt these now to make future outages less painful:

• AI-augmented incident assistants — use LLM-powered runbooks to summarize logs and suggest next steps, but maintain human oversight for final actions. For securing on-desktop AI agents and policies, see secure AI agent policy guidance.
• Edge-first observability — instrument edge compute (Workers, Edge Functions) so traces preserve context across edge-to-origin hops. Tactics for low-latency hybrid production and edge observability are covered in Edge-First Live Production Playbook.
• Contract-level resilience — include availability and escalation SLAs in vendor contracts; require post-incident reports from providers for Sev0/Sev1 incidents.

Real-world example (anonymized)

In late 2025, a mid-market SaaS experienced a regional CDN outage that surfaced as a sudden 60% failure rate for API calls originating in a major metro. Early detection relied on synthetic tests. The team used a preconfigured Route 53 failover record to direct traffic to a secondary origin and published status updates every 20 minutes. The RCA found a combination of provider peering issues and an internal DNS TTL set to 24 hours, delaying customer recovery. Actions included lowering TTLs, enabling multi-CDN failover, and adding a new synthetic suite that covered edge-worker paths. MTTR dropped by 75% on subsequent drills. For a similar incident analysis and postmortem, see this postmortem.

Practical takeaways — what to implement this week

1. Define CDN/cloud outage severity levels and map communication owners.
2. Implement at least one synthetic test that mimics a high-value user flow through the CDN.
3. Set DNS TTLs for critical records to 60–120 seconds where automated failover is required.
4. Draft a one-page postmortem template and mandate its completion for all Sev1+ incidents.
5. Schedule a failover rehearsal for your primary traffic path this quarter.

Closing — continuous improvement and the next steps

Outages involving CDNs and public clouds will continue to be one of the primary operational risks in 2026. But with a repeatable incident playbook, automated detection, and disciplined postmortem practices, you can reduce recovery time and limit business impact. Use the supplied templates and runbook snippets as a starting point, iterate after each drill or incident, and measure improvement against concrete metrics.

Call to action: Want the editable incident and postmortem templates (Markdown & JSON), runbook automation snippets for Terraform/AWS, and a failover rehearsal checklist shipped to your inbox? Download the free toolkit and sign up for a 30-minute clinic with our reliability engineers to run a tabletop exercise tailored to your architecture.

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