
Before You Build It: The AWS Primitive That Replaces the Custom Piece
A lab design review still had a cron server for a nightly job. Classic Lambda had already stopped at 900 seconds. Name the primitive, or name the stop-rule that keeps the box.
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A lab design review still had a cron server for a nightly job. Classic Lambda had already stopped at 900 seconds. Name the primitive, or name the stop-rule that keeps the box.

When to keep Customer.io/Loops vs build journeys with EventBridge + Step Functions + SES — stream isolation, RFC 8058, Pro for DIPs, and a first-party journey architecture checklist.

After Mar–May 2026 LMI updates (32 GB / 16 vCPU, 4,096 FDs, EventBridge scheduled scaling), a B2B analytics API (~40k peak RPM, 9–6 UTC) cut idle capacity cost ~62% by scheduling MinExecutionEnvironments 20→3 off-peak.

For a mid-market 3PL (~2.1M shipments/yr, OTIF 82%), layering AWS Supply Chain on ERP ingest plus Location Services fleet tracking moved ETA accuracy from 71% to 87% in 90 days — without replacing Manhattan WMS.

Event-driven sounds elegant in design docs. Then a malformed event ships to a critical bus and you spend a weekend debugging fan-out. EventBridge buses, rules, schema discovery, cross-account patterns, and the failure modes you only learn about in production.