Automated Runbooks for CDN/DNS Outages: Code-First Playbooks for Ops Teams

Safe execution patterns (approval, dry-run, and rollback)

Automation must be safe. Use this three-stage approval model in your CI/CD incident pipeline:

1. Dry-run: Terraform plan or Ansible check mode. Synthetic checks run and report expected impact.
2. Approval gate: A human approves via Slack/Jira/PR comment to trigger the execution job. For regulated teams consider aligning approval controls with your compliance posture (see FedRAMP and platform procurement notes at what FedRAMP approval means).
3. Execute + monitor: Run the playbook; monitor synthetic checks and RUM for 3–10 minutes. If errors increase beyond thresholds, auto-rollback.

Terraform dry-run and apply in incidents

Keep a pipeline job that runs terraform plan and posts the plan to the incident channel. The apply step should require approval. Example concisely:

# CI step: plan
terraform init
terraform plan -var='incident=true' -out=tfplan
# Human reviews UI artifact, then approves
terraform apply tfplan

Progressive traffic steering: reduce blast radius

Instead of flipping all traffic, use weighted DNS or CDN steering to shift a percentage to the backup origin. This lets you validate backup health with production traffic. Combine weighted records with your edge caching strategy to limit cache churn and latency.

resource "aws_route53_record" "prod_weighted" {
  zone_id = var.zone_id
  name    = "www.example.com"
  type    = "A"
  set_identifier = "primary-90"
  weight = 90
  ttl = 60
  records = [aws_instance.primary.public_ip]
}

resource "aws_route53_record" "backup_weighted" {
  zone_id = var.zone_id
  name    = "www.example.com"
  type    = "A"
  set_identifier = "backup-10"
  weight = 10
  ttl = 60
  records = [aws_instance.secondary.public_ip]
}

Testing your automated runbooks — don’t wait for an outage

Schedule failure drills (monthly or quarterly) and runbook run-throughs. Key steps:

• Simulate primary origin failure with a synthetic monitor that returns 500 for 3+ checks.
• Run your Terraform/Ansible playbooks in a staging zone or with subdomains, then examine propagation and rollback speed.
• Use chaos engineering for more advanced teams to inject CDN/DNS faults in a controlled manner — pair these drills with data and pipeline hygiene guides such as ethical data pipelines so test telemetry is usable and auditable.

Security, RBAC, and auditing

Treat runbook triggers like code deployments.

• Use short-lived credentials (OIDC, IAM roles) from CI and platforms (GitHub Actions, GitLab CI) to avoid long-lived secrets.
• Restrict who can approve incident runbooks. Use separate reviewers for DNS changes and for CDN purges if possible — integrate identity and verification tooling similar to vendor assessments described in identity verification vendor comparisons.
• Log every change — Cloudflare/AWS provide audit logs. Store CI artifacts and the exact payloads for post-incident review.

Operational considerations and pitfalls

• DNS caching: Even with 60s TTLs, some resolvers ignore TTLs; expect a small fraction of users to be cached longer.
• Rate limits: CDN APIs and providers throttle purges or changes; batch where possible and prefer targeted purge lists to global invalidations.
• Cold caches: Rerouting creates cold cache traffic to the backup origin; ensure cost/scale limits are acceptable.
• Provider-specific behavior: Cloudflare proxied records change CNAME behaviors. Test how your DNS provider and CDN interact before relying on an automated switch.

Advanced strategies for 2026 and beyond

As of 2026, teams are adopting these higher-maturity patterns:

• Policy-as-code: Enforce safety policies (e.g., require TTL <= 120s during incident mode) with tools like Open Policy Agent in your CI pipeline; tie those rules into procurement and platform compliance checks (see notes on FedRAMP for regulated buyers).
• Multi-CDN with centralized steering: Use DNS or managed steering solutions to switch between CDNs with a single control plane and complement with edge caching strategies.
• Edge compute fallback: Deploy read-only fallbacks (edge workers) that serve stale content when origin and CDN both fail.
• Automatic rollback thresholds: Set RUM/metrics thresholds that trigger automatic rollbacks. Keep thresholds conservative to avoid flip-flopping; design your telemetry to feed into predictive systems like those described in predictive monitoring workflows.

Post-incident: learn and harden

After the incident, complete a blameless postmortem with these concrete outputs:

• Timeline of automated steps and approvals (CI logs, audit trails).
• Which automated actions worked and which required manual intervention.
• Action items: reduce TTLs for critical records, add more targeted purge endpoints, increase synthetic monitors, or add secondary origins.

"Automate only what you trust — and design your runbooks so that trust can be tested and measured."

Checklist — Build a battle-tested CDN/DNS incident runbook

• Store runbooks as code in Git (Terraform + Ansible examples folder)
• Pre-create health checks and secondary origins
• Set incident-mode TTLs (60–120s) and document revert values
• Implement a CI pipeline: plan -> approve -> apply
• Instrument automated rollback thresholds with RUM and synthetic monitors
• Run regular failover drills and keep playbooks up-to-date

Actionable takeaways

• Convert your manual runbooks into IaC + playbooks and keep them in Git for auditability.
• Use short TTLs and backup origins to reduce time-to-failover; test in staging first.
• Automate caches and origin updates with Ansible and provider APIs, but gate global failovers with human approvals. Tie the automation into distributed systems patterns like micro-DC and PDU orchestration where applicable for private-hosted fallbacks.
• Keep a documented rollback path and automatic rollback triggers tied to measurable thresholds.

Further reading and references (2025–2026 context)

Major CDN/DNS incidents in late 2025 and January 2026 reinforced the need for automated runbooks and multi-provider resiliency. If you want to explore real incident reports and postmortems, review provider status pages and public postmortems from Cloudflare, AWS, and others from that window — they contain concrete failure modes you can model in your drills. Also see practical guidance on hardware cost and capacity planning when sizing backups and warm standbys.

Call to action

Start your runbook automation project today: fork a Git repo with the examples above, wire it to your CI with an approval gate, and run a staged failover drill this week. Want a ready-to-run template? Download our curated GitOps runbook starter (Terraform + Ansible + CI) and join the dummies.cloud community workshop where we’ll walk through a live simulated CDN/DNS incident. For hands-on migration tips and realtime alternatives to vendor-hosted control planes, read about running realtime workrooms and non-proprietary architectures at run realtime workrooms without Meta.

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