AWS us-east-1 outage cascaded through four hidden third-party dependencies
incident.io's on-call notifications were delayed for over two hours, SAML authentication was intermittently unavailable, Scribe's AI note-taker was offline for ~5 hours, and the deployment pipeline was blocked — all driven by AWS us-east-1 dependency propagation through their telecom provider, auth provider, transcription provider, and Docker Hub.
Third-party provider risk runs much deeper than your direct dependencies — audit not just which services you integrate with but which cloud provider each one runs on, and verify that your deployment pipeline itself has no implicit dependencies on the same failing infrastructure you need to fix.
AWS us-east-1 experienced a major outage at 07:11 UTC, taking down the telecom provider incident.io relied on for SMS and phone call delivery of on-call notifications.
Telecom provider failure → SMS/phone notification requests started timing out after retries → notifications shared queue capacity with Email, Slack, and push channels, so all delivery types backed up → team tried to deploy code fixes but their build pipeline implicitly depended on Docker Hub, which runs on AWS and was also down → deployment blocked; in parallel, the escalation worker's Postgres index filled with dead tuples from the burst of activity, making more workers counterproductive rather than helpful.
Design an on-call notification system that remains operable when both your telecom provider and your deployment pipeline are simultaneously unavailable — what redundancy and pre-baked fallback mechanisms would you build in?
