Runbooks for Hybrid Outage Scenarios: CDN + Cloud + On-Prem Storage

Hook: When CDN, Cloud, and On‑Prem All Fail — What You Do First Matters

Hybrid architectures give you resilience and flexibility — until they don’t. In 2026, the most costly incidents aren’t single-service failures but complex, cross‑layer outages that simultaneously impact your CDN, cloud provider, and on‑prem storage. If your team doesn’t have short, prioritized runbooks ready, you will waste precious minutes on coordination, increase regulatory risk, and frustrate customers. This guide gives concise, battle‑tested runbook templates for hybrid outage scenarios, with prioritized mitigation steps, communication plans, and escalation rules you can apply immediately.

Top takeaways (read first)

• Prioritize safety, evidence, and continuity: preserve data integrity and create an auditable timeline before executing writes or mass failovers.
• Timebox actions: T+5, T+15, T+30 decision windows keep teams aligned and reduce costly guesswork.
• Use layered fallbacks: stale‑cache serving, alternate CDN/providers, and cloud replication let you keep critical paths alive.
• Communicate early and often: internal alert → external status → client updates. Use templates to avoid noisy, inconsistent messages.
• Automate safe switches: feature flags, GitOps, and IaC dramatically reduce risk during failover.

Why hybrid outages look different in 2026

Late 2025 and early 2026 saw a string of high‑profile multi‑service incidents where CDN and cloud control planes experienced correlated failures. These events exposed two realities: modern web stacks are more distributed and more interdependent, and regulatory scrutiny around availability, data residency, and notification timelines has increased. At the same time, teams now have stronger tools — fast DNS providers, multi‑CDN vendors, AI‑assisted incident responders, and mature GitOps — enabling safer, faster mitigation when runbooks exist and are practiced.

Runbook design principles (short & enforceable)

• Keep it action‑first: first 5 actions are always the most critical; nonessential tasks are deferred.
• Timebox decisions: set clear T+X windows for detect, escalate, mitigate, recover.
• Avoid assumptions: verify service health with multiple independent probes (DNS, BGP, API endpoints).
• Preserve forensics: capture logs and snapshots before destructive changes.
• Automate the safe path: script the rollback as rigorously as the forward action.
• Single source of truth: update status page and incident channel first; every action is logged.

Incident classification and SLAs

Define severity levels up front so teams share language.

• SEV1 (Total outage): customer‑facing availability is lost or critical workflows blocked. Immediate all‑hands.
• SEV2 (Partial outage): degraded performance or partial feature loss impacting many customers.
• SEV3 (Minor): isolated incidents, single customer, or noncritical background tasks.

Roles & escalation matrix (template)

Assign names and backups. Harden 24/7 contacts and publish in the incident channel.

• Incident Commander (IC): leads decisions, communications, and triage (T+0 to T+60).
• SRE Lead: executes mitigations, monitors metrics, runs failovers.
• Network Lead: handles CDN/DNS/BGP actions and peering checks.
• Storage Owner: on‑prem and cloud storage decisions, data integrity checks.
• Security/Compliance: assesses breach risk and regulatory notification obligations.
• Comms/Customer Success: drafts status updates and customer emails.
• Exec Sponsor: notified for SEV1 within T+15 and kept updated every 30 minutes.

Timeboxed escalation play (quick reference)

1. T+0 — Detect & declare: IC declared if SIEM/monitoring crosses SEV threshold. Open incident channel and status page stub.
2. T+5 — Initial triage: confirm scope (region, service, customer impact). Gather logs and capture error rates.
3. T+15 — Mitigation decision: choose mitigation path (DNS failover, toggle feature, serve stale) and assign tasks.
4. T+30 — Execute mitigations: implement automated or manual actions and monitor result for 15 minutes.
5. T+60 — Recovery or escalated response: if mitigations fail, escalate to execs and enact emergency measures (maintenance pages, partner failover).

Runbook templates: concise, copy/paste ready

Each template below follows the same structure: Detect → Triage → Prioritized Mitigation Steps → Communication → Escalation. Replace bracketed tokens with your values and test them in drills.

Scenario A — CDN outage; cloud & on‑prem healthy

Typical signs: increased 5xx from edge, CDN provider status reports, downDetector spikes.

Detect

• Edge 5xx rate > X% for > 2 minutes.
• CDN provider status page confirms degraded POPs.

Triage (T+5)

• Confirm if only static assets are affected or dynamic APIs as well.
• Verify DNS resolution and certificate health for CDN domains.

Prioritized mitigation steps (T+15 → T+60)

1. Enable stale‑while‑revalidate / serve stale cache: toggle in CDN control panel or via API. This preserves GET availability for cached assets.
2. Switch to secondary CDN using preconfigured domain (e.g., assets-secondary.example.com) and short TTL DNS swap. If using multi‑CDN provider, trigger provider failover runbook.
3. Reduce asset load: enable critical CSS inline, remove nonessential third‑party scripts via feature flags to reduce edge load.
4. If performance is still bad, deploy a minimal maintenance page served from cloud origin (S3/Blob) and point a subset of traffic to it using traffic‑splitting rules.
5. Monitor cache hit ratio, 5xx/4xx, origin request surge—throttle origin traffic to prevent origin overload.

Communication

• Internal (T+10): Slack #incident with current scope and T+15 action plan.
• Public status (T+20): “We are experiencing CDN edge disruptions; static assets may fail to load. Mitigations underway.”

Escalation

• If secondary CDN failover does not restore 70% of edge traffic in T+30 → escalate to Exec Sponsor and consider manual DNS TTL reductions and global failover.

Scenario B — Cloud provider control plane / APIs degraded; CDN & on‑prem OK

Signs: API timeouts, IAM errors, inability to provision or authenticate services.

Detect

• Cloud provider status shows control plane impacted; authentication/API errors spike.
• CI/CD or IaC fails to apply new changes.

Triage (T+5)

• Identify scope: management plane vs data plane. Can data plane (S3, VMs) still serve traffic?

Prioritized mitigation steps

1. Stop all nonessential control plane operations (deploys, scaling actions) to avoid inconsistent state.
2. Enable cached credentials and pre‑signed tokens where possible to maintain session continuity for clients.
3. Failover to secondary cloud account/region if cross‑account replication is configured and tested.
4. For critical writes that must succeed, hold requests in a durable queue (Kafka, SQS, regional queue). Log and persist locally until cloud writes can resume.
5. If authorization is failing (IAM), use pre‑approved emergency keys with strict TTL and rotate after recovery.

Communication

• Internal (T+10): Note whether data plane is healthy; advise all teams to pause config changes.
• Public status (T+30): Explain degraded management APIs may affect provisioning/scaling but customer traffic should be unaffected if data plane is healthy.

Escalation

• If data plane degrades within T+60, escalate to SEV1 and follow combined outage playbook.

Scenario C — On‑prem storage failure; CDN & cloud OK

Typical causes: SAN/NAS failure, network fabric partition, backup replication lag.

Detect

• I/O errors, mount failures, or replication lag alerts from storage controllers.

Triage (T+5)

• Is the on‑prem system a primary write target? Are replicas current?
• Check RPO/RTO impact and whether regulatory constraints require local residency for certain datasets.

Prioritized mitigation steps

1. Stop writes to the affected filesystem. Switch applications to read‑only mode if possible.
2. Promote cloud replica to primary for affected datasets if replication is up‑to‑date and allowed by policy.
3. Mount cloud storage through a gateway (e.g., S3FS, blobfuse, or vendor storage gateway) for transparent application access—only after verifying performance and security controls.
4. Prioritize critical customer data flows; move archival and low‑priority datasets to cold cloud storage later.
5. Start forensic snapshot and export logs for compliance if data loss is suspected.

Communication

• Internal: Notify Storage Owner and Compliance if any customer data residency obligations are implicated.
• Public: If customer impact is confirmed, publish status and ETA for read/write restoration.

Escalation

• Escalate immediately to Security and Legal if data integrity or leakage is suspected.

Scenario D — Triple outage (CDN + Cloud + On‑Prem) — emergency runbook

This is the worst‑case incident. The goal is to preserve critical customer journeys, maintain data integrity, and communicate clearly. Execute only after initial evidence capture.

Detect

• Multiple independent probes show 5xx/timeout across CDN, cloud APIs failing, and on‑prem storage errors.
• Multiple geographic regions report incidents. Expect external provider statements.

Immediate actions (T+0 → T+15)

1. IC declares SEV1, opens incident channel, and posts initial status: scope, estimated impact, next update timeline.
2. Preserve evidence: snapshot router configs, capture controller logs, export cloud audit logs via secondary routes (if possible).
3. Block potentially risky automation (IaC pipelines, autoscalers) to avoid cascading changes.

Prioritized mitigation (T+15 → T+60)

1. Activate prebuilt static emergency site (hosted offsite or via a secondary provider) to display status and critical account info. Use low‑TTL DNS to point critical hostnames to it.
2. Enable minimal operational mode: allow critical authentication and billing APIs only via cached tokens or emergency endpoints.
3. Queue writes locally with durable store (append‑only logs) and ensure they are cryptographically signed and timestamped for later reconciliation.
4. Engage provider support channels in parallel (account rep, escalation hotline) and share evidence bundle to accelerate response.
5. Notify legal and compliance per regulatory timelines (e.g., GDPR/HIPAA deadlines) even if investigation is ongoing.

Communication

• External (T+30): Clear acknowledgement: impact, affected services, mitigation steps, and next update time.
• Customers with SLA exposure: targeted outreach via email/phone, explain remediation path and potential credits if applicable.

Escalation

• If no progress by T+60, schedule executive briefing and prepare public remediation timeline and potential compensations.

Practical command snippets & automation patterns

Examples you can add to runbooks (replace tokens):

• Fetch origin health: curl -sS -D - https://origin.example.com/health | jq
• Copy critical object to emergency bucket: aws s3 cp s3://prod-bucket/key s3://emergency-bucket/key --profile emergency
• Mount cloud storage (testing only): rclone mount emergency: /mnt/emergency --daemon
• Trigger CDN API to serve stale: curl -X POST https://api.cdn.example/v1/cache/serve_stale -H 'Authorization: Bearer ${TOKEN}'

Communication templates (short & clear)

Internal (incident channel)

SEV1 declared — CDN+Cloud+On‑Prem impacted. IC: @name. Scope: all public frontend assets 503, control plane 5xx, on‑prem SAN I/O errors. T+15 mitigation: activate static emergency site + enable stale edge serving. Next update T+15. Actions: SRE → stale toggle, Network → DNS TTL reduce, Storage → snapshot.

Public status (short)

We’re experiencing degraded service affecting asset loading and some API endpoints. Our team is actively mitigating and will provide updates at [time]. We apologize and appreciate your patience.

Customer notification (for impacted SLAs)

Dear [Customer], we’ve detected a service incident impacting [services]. Mitigations are underway. We will send a follow‑up within [X] and provide a detailed incident report after recovery. Contact [support link] for urgent cases.

Post‑incident: recovery checklist & learning loop

• Confirm full functional recovery through synthetic checks and customer validation.
• Collect artifacts: logs, packet captures, snapshots, change history.
• Run immediate data integrity verification between replicas and on‑prem storage.
• Write an RCA within 72 hours: timeline, root cause, contributing factors, remediation, and owner for each action.
• Update runbooks and IaC to codify fixes (e.g., add secondary CDN, shorten TTLs, add emergency buckets).
• Hold a postmortem war‑game that includes execs and customer success to align on future SLAs and compensations.

Testing: how often and what to simulate in 2026

Industry best practice in 2026 is monthly table‑top exercises and quarterly live simulations that include:

• Multi‑provider failovers (CDN & cloud) executed in a non‑production environment.
• Write‑queue and reconcile drills to ensure no data loss during cloud or storage writes.
• Communications drills with legal and customer success to validate messaging and templates.
• Chaos engineering experiments limited to game days for on‑prem and CDN components.

Advanced strategies & 2026 trends to adopt

• Multi‑control plane resilience: adopt dual management accounts, secondary provider credentials, and preapproved emergency keys with strict rotation policies.
• Edge compute & snapshots: leverage distributed edge object snapshots that can be surfaced via a low‑cost static host in emergencies.
• AI‑assisted incident triage: train models on your historical incidents to suggest mitigations and prioritize runbook tasks.
• GitOps for incident actions: keep emergency DNS records, failover configs, and static site content in a fast‑path Git repo with automated rollbacks.
• Policy as code for compliance: codify data residency and breach notification triggers so your runbook automatically surfaces regulatory obligations.

Real‑world example (reference)

Recent cross‑provider incidents in late 2025 and early 2026 demonstrated that CDN edge failures often correlate with cloud control plane anomalies under load. Teams that recovered fastest had preconfigured secondary CDNs, emergency static sites, and baked‑in write queuing. Use these lessons: prepare layers of fallback, preserve forensics, and practice the runbooks you write today.

Final actionable checklist (one page)

• Publish a SEV definition and escalation matrix prominently.
• Create one‑page runbooks for CDN outage, cloud control plane, on‑prem storage, and triple outage.
• Preconfigure secondary CDN, emergency buckets, and short‑TTL DNS entries.
• Automate safe toggles: stale serving, read‑only modes, and emergency tokens.
• Run monthly tabletop drills and quarterly live failovers.
• Keep communications templates and regulatory checklists ready.

Call to action

If you don’t already have concise runbooks for hybrid outages, start with the templates above. Download a checklist, codify your emergency tokens, and schedule your next tabletop drill this quarter. For teams needing a jumpstart, we provide a ready‑to‑fork runbook repository and incident playbook workshop tailored for cloud + CDN + on‑prem stacks — contact us to schedule a workshop or request the templates in your preferred format.

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