Incident Postmortem Template for SaaS/CDN Outages (with Example Playbook)

UUnknown

2026-02-04

11 min read

Reproducible, blameless postmortem template and playbook for Cloudflare/X/AWS outages—what to log, how to communicate, and actionable remediation.

Hook — When CDN or Cloud Providers Fail, Your team is judged on the postmortem

Outages that trace back to Cloudflare, X (formerly Twitter) or AWS don’t just break pages — they break trust. For technology leads and DevOps teams in 2026, the differentiator isn’t that downtime happens; it’s how fast you detect, communicate, and permanently fix the root causes. This article gives a reproducible, blameless postmortem template and an actionable example playbook tuned for SaaS/CDN outages: what to log, how to communicate externally, and the remediation plan that prevents recurrence.

Why this matters now (late 2025–2026 trends)

More edge complexity: Multi-CDN, edge compute and origin-shielding are standard in 2026—increasing failure modes.
Supply-chain and routing incidents: Supply-chain, BGP, DDoS mitigation, and third-party waf/CDN misconfigurations remain leading causes of wide-impact outages.
AI observability: Teams increasingly use ML for anomaly detection; that helps but introduces alert-noise and blind spots when signals shift during global incidents.
Stricter SLAs and compliance: Customers demand clear SLO/SLA evidence; regulators require precise incident records for some industries.

Inverted pyramid: What you need immediately

If you’re mid-incident, do these three things now:

Open an incident channel (dedicated Slack/Teams room + video bridge). Record timestamps.
Publish a public status message (status page + Twitter/X) with current impact, affected services, ETA for next update.
Collect key telemetry snapshots (edge error rate, 5xx counts, synthetic checks, BGP route table, DNS resolution, Cloudflare / CDN debug IDs).

Postmortem Template — reproducible and blameless

Use this as a living template. Keep it short, timestamped, and focused on facts and actionables.

Template fields

Incident ID: unique (e.g., 2026-01-16-CF-AWS-001)
Severity / Impact: S1/S2 etc., services impacted, % of traffic/users affected
Timeline (UTC): ordered, timestamped events with operator initials
Summary: one-paragraph summary of what happened and final resolution
Root Cause(s): explicit root cause(s) vs contributing factors
Detection: how it was detected, by whom, and which alerts fired
Mitigation steps taken: chronological list, who executed, outcome
Customer communications: status page posts, social media, support scripts, and timestamps
Logs & evidence collected: exact artifacts, storage locations, retention
Impact analysis: downtime length, SLA/SLO breach calc, revenue/contract exposure
Action items / remediation plan: owner, due date, verification method, priority
Lessons learned: culture/process/tool changes
Appendices: raw logs, traceroutes, timeline chat transcripts (redacted), command outputs

What to log during a CDN / SaaS outage (exact checklist)

Good postmortems are only possible with good evidence. Log these in real time and preserve immutable copies:

Essential telemetry

Edge error rates and error types (4xx vs 5xx) by POP (Cloudflare/NW PoP tags).
Origin latency and 5xx rates (from ALB/NLB/CloudFront logs or ELB access logs).
Cache hit/miss ratios, purge events, and cache TTL changes.
DNS resolution timelines (query timestamps and TTLs) and authoritative server responses.
BGP route-change events and any routing policy updates (dates, AS numbers).
WAF / rate-limit blocks and mitigation rules triggered.
Synthetic check results (multiregional) and last-known-good timestamps.
Application logs with request IDs and correlation IDs; preserve at least 7–30 days immutable copy.
Cloud provider status page links and provider incident IDs (Cloudflare incident ID, AWS case ID).

Network-level diagnostics

mtr/traceroute to affected endpoints from multiple regions (attach outputs).
tcpdump / pcap snippets for representative flows covering failures.
VPC Flow Logs / Security Group log samples for blocked traffic.

Human traces

Slack/incident channel transcript (timestamped) — archive snapshot.
Who did what and when (role-based actions logged in ticketing system).
Customer support tickets and escalation calls (time and summary).

How to communicate externally — template messages that scale

External comms should be frequent, factual, and non-speculative. Maintain copies of these templates in your runbook and link them to any automation you use for updates.

Status page / Incident start (first 15 minutes)

Title: Partial outage affecting API and dashboard (investigating)

Message: We’re investigating increased error rates affecting our API and dashboard for some users. Our engineering team is actively investigating. We will post updates every 30 minutes. Impact: some API requests may return 5xx. No action required from customers at this time.

Customer email — 1 hour in

Subject: Incident Update — Service Disruption Impacting Dashboard/API

We are experiencing an incident impacting the Dashboard and API. Our investigation shows an upstream CDN routing issue affecting traffic to our origin. We have mitigation steps underway and expect the next update at [time]. If you rely on critical endpoints, consider temporary retries/backoff in your clients. We will provide a full post-incident report within 72 hours.

We’re aware of a service disruption impacting some users. Our team is investigating and will post updates on the status page. We’ll share a detailed postmortem when the incident concludes.

Blameless RCA: separating the root cause from contributing factors

In 2026, teams that practice blameless RCAs move faster and improve system design. Structure your analysis:

Root cause: the single change or failure that directly set the chain in motion.
Contributing factors: conditions that increased blast radius or delayed detection (monitor gaps, stale runbooks, single vendor dependency).
Corrective vs preventive actions: quick mitigations (rollback, routing change) vs long-term infrastructure changes.

Example Incident: Cloudflare routing change + AWS origin connectivity

Below is an anonymized, reproducible example postmortem for a mixed Cloudflare / AWS outage. Use it as a direct template you can adapt.

Incident ID

2026-01-16-CF-AWS-001

Severity / Impact

S1 — 45 minutes complete outage for 38% of traffic (US-East and EU-West). Dashboard and API returned 502/524 errors. No data loss; retries attempted by clients increased error counts.

Timeline (UTC)

2026-01-16 12:22 — Synthetic checks alert: API latency spike and 524 errors (regional probes).
12:24 — Monitoring alert escalated to on-call; incident channel opened.
12:28 — Engineering observes Cloudflare reported errors in POPs and Cloudflare status page shows internal routing anomaly (CF-INC-44521).
12:32 — Traceroutes show blackholing to origin from specific Cloudflare POPs; BGP lookups show no AS changes.
12:38 — Temporary mitigation: change Cloudflare origin IP to alternate ENI in a different AZ; route propagation begins.
12:55 — Error rates drop and traffic recovers; continued monitoring until 13:07 when incident declared resolved.

Summary

Traffic from certain Cloudflare PoPs experienced failed keepalive connections to our primary origin ENI, causing repeated 524 timeouts. Switching the origin to an alternate ENI in a different AZ restored connectivity. Cloudflare root cause was an internal POP routing and TCP-handshake failure. AWS network health showed no broader degradation.

Root Cause

Primary: Cloudflare POP routing anomaly causing TCP handshake failures to our origin IPs.

Contributing: (1) Single origin IP with long TTL used in DNS; (2) insufficient multiregion synthetic checks focused on the failing POP; (3) client retry logic caused retry storms increasing load. This is a classic example where automation and trust intersect with observable blind spots.

Detection

Detected via synthetic monitors and Cloudflare edge error alerts. Our on-call playbook triggered within two minutes after synthetic alarms; manual confirmation took additional 4 minutes.

Mitigations performed

Switched Cloudflare origin to alternate ENI with new origin IP (12:38) to bypass blocked path.
Adjusted origin keepalive and lowered idle timeout to avoid stuck TCP sessions.
Scaled origin instances up by +30% to absorb retry storms.
Posted frequent updates on status page and social channels.

Customer communications

12:30 — Status page: investigating increased errors.
12:45 — Status page + email: partial service restored for some users; mitigation underway.
14:00 — Follow-up email: postmortem to be shared within 72 hours.

Logs & evidence

Cloudflare trace IDs: saved to /incidents/2026-01-16/cloudflare-traces.log
ELB access logs (12:00–13:30 UTC): s3://company-incident-logs/2026-01-16/elb/
Traceroute outputs from three regions attached to the incident ticket.
Slack channel transcript archived as PDF (redacted).

Impact analysis

Downtime with degraded availability lasted 45 minutes for 38% of traffic. SLA targets (99.95% monthly) were not breached for most customers, but premium SLAs requiring <5 minutes MTTR experienced impact for a small subset. No data integrity issues discovered.

Action items (owner — due date — verification)

Implement multi-origin DNS with low TTL and health checks — Owner: Infra Lead — Due: 2026-02-01 — Verification: Chaotic failover test across regions.
Enable Cloudflare origin shield + origin failover and automate origin IP rotation — Owner: Edge Team — Due: 2026-01-25 — Verification: Fire drill simulation routing through alternate origin. See also edge-oriented patterns for guidance on reducing tail latency.
Expand synthetic monitoring to include per-POP probes for top 10 CDNs — Owner: SRE — Due: 2026-01-28 — Verification: Dashboard showing POP-level p95 latency within threshold for 14 days.
Implement client-side exponential backoff with jitter to reduce retry storms — Owner: API Team — Due: 2026-02-05 — Verification: load tests demonstrating reduced concurrent retries.
Run a quarterly vendor failover drill (multi-CDN) — Owner: Ops Manager — Due: 2026-03-31 — Verification: documented drill report and post-drill followups. Consider adding the vendor drill into your runbook templates for consistency.

Lessons learned

Single-vendor edge dependencies increase systemic risk. In 2026, multi-CDN strategies with controlled cost are practical and recommended.
Monitoring must be POP-aware; aggregate alerts hide localized failures. Consider map-aware instrumentation like micro-map orchestration for POP-level visibility.
Public communications cadence matters — customers prefer timely partial updates over perfect accuracy. See perspectives on trust and automation for guidance on balancing speed and accuracy.

Playbook: Step-by-step checklist for a CDN-origin outage

Initial detection (0–5m):
- Trigger incident channel; assign Incident Commander (IC).
- Run quick probes: curl, traceroute, and DNS dig from three regions.
- Publish initial status page message (template above).
Triage (5–15m):
- Check CDN provider status and incident ID; capture their debug trace IDs.
- Confirm if failure is client-side, CDN, or origin using multi-region synthetic checks and origin logs.
Mitigation (15–60m):
- Apply short-term mitigation (switch origin IP, change routing to alternate ENI, temporary cache TTL increases).
- If necessary, engage vendor support and request detailed trace logs and timeline.
Stabilize & communicate (60–120m):
- Confirm traffic recovery via sitemonitor & analytics; provide customer update and ETA for postmortem.
- Collect artifacts for postmortem and close incident after sustained healthy metrics.
Post-incident (24–72h):
- Draft postmortem using the template; run blameless RCA and assign action items.
- Share postmortem publicly and internally; schedule follow-up verification tasks.

Monitoring & CI/CD improvements to prevent recurrence

Practical steps to harden your pipeline and observability:

Synthetic monitoring: instrument per-POP and per-region probes, include TCP/TLS handshake checks. Use multivendor probes (Catchpoint, Uptrends, Datadog RUM).
Alerting: use dynamic baselines and reduce alert fatigue via composite alerts (e.g., edge 5xx p95 across multiple regions).
Deployment practices: separate config rollouts (CDN/WAF rules) from application deployments; run canary config changes to small PoPs first.
CI/CD integration: automate health-check smoke tests post-deploy (curl + health endpoints), and fail rollbacks automatically on p99 degradation. See our CI/CD playbook on how to integrate unusual checks like favicons into pipelines: How to Build a CI/CD Favicon Pipeline — Advanced Playbook (2026).
Infrastructure as code: keep origin failover and multi-origin DNS in Terraform/CloudFormation and test it in staging with real traffic mirroring. For cloud isolation patterns and stronger controls, review AWS European Sovereign Cloud guidance.

Legal, compliance and SLA considerations

Documenting the incident precisely aids legal and contractual responses:

Record exact downtime windows (UTC) and affected customers lists for SLA calculations.
Preserve immutable logs and chain-of-custody for regulated sectors; consider using WORM storage.
Coordinate PR and legal teams before external postmortems if the incident has legal/regulatory exposure. Recent procurement shifts and incident-response buying guidance may affect disclosure requirements — see public procurement draft guidance.

Quick reference: useful commands & alert rules

Drop these into your runbook for immediate use.

# Multi-region curl with trace-id header
curl -s -D - -o /dev/null -w "%{http_code} %{time_total}\n" -H "X-Trace-Id: incident-2026-01-16" https://api.example.com/health

# Basic traceroute
traceroute -n api.example.com

# Example Grafana alert: edge_5xx_rate > 2% for 5m across >1 region
expression: sum(rate(edge_http_response_status{status=~"5.."}[5m])) / sum(rate(edge_http_requests_total[5m])) > 0.02

Measuring success after fixes — verification checklist

Run simulated failover tests for origin and CDN at least quarterly.
Track action item closure and verification evidence in ticket system; reopen if metrics regress within 90 days.
Introduce a postmortem follow-up 30 days after incident to confirm long-term effectiveness.

Final takeaway — make postmortems operational

In 2026, outages tied to Cloudflare, X, or AWS will continue. The teams that reduce customer impact do three things well: (1) instrument everything with per-POP observability, (2) run automated, tested failover strategies, and (3) publish timely, factual communications while producing blameless RCAs with measurable action items. Use this template and the example playbook to turn outages into repeatable learning and long-term resilience.

Call to action

Need a tailored incident postmortem template and playbook for your stack? Get a free 30-minute runbook review with our SRE team — we’ll audit your monitoring, CI/CD gates, and external-comms templates and give prioritized remediation steps you can implement in 2 weeks. Contact us to schedule.

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