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Amazon CloudWatchSynthetics

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CloudWatch Synthetics runs canaries — scripted probes that periodically check URLs and multi-step journeys — for availability monitoring distinct from deploy canaries.

Platform & Operations. Last reviewed July 2026.

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Definition

Amazon CloudWatch Synthetics runs canaries — scheduled scripts (heartbeat/API or browser) that probe endpoints and user journeys, emit success and latency metrics, and optionally store screenshots/HAR artifacts. Use Synthetics to detect customer-visible outages even when infrastructure metrics look healthy.

When to use it

  • Tier-1 journey availability (login, checkout, critical API)
  • External measurement to complement Application Signals backend SLOs
  • SLA reporting that requires synthetic success ratios

When not to use it

  • As a substitute for load testing
  • High-frequency browser fleets without a cost owner
  • Confused with deploy canaries (progressive delivery) — different concept

Tips

  • Prefer API canaries when a full browser is unnecessary
  • Page on SuccessPercent with owners/runbooks (monitoring vs alerting)
  • Align canary journeys with Application Signals SLOs

Gotchas

Serious

  • 1-minute intervals across many canaries dominate CloudWatch spend
  • Private VPC misconfig causes false failures

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Pictures:James Murray in the Scriptorium (public domain); Card Division of the Library of Congress, 1900–1920 (public domain); Salle des catalogues, Bibliothèque Mazarine, Paris, Marie-Lan Nguyen (CC BY 2.0); Copyright card catalog drawer, Michael Holley Swtpc6800 (public domain); Type in sort case, Edinburgh City of Print (CC BY 2.0); Widener Library reading room, 1920 (public domain). Via Wikimedia Commons.