Lambda shines for bursty traffic, scheduled jobs, and glue between SaaS systems. For steady high-QPS APIs, the math on per-invocation pricing, concurrency, and latency variance may point you to Fargate or a small always-on fleet instead.

Design checks

  • Set reserved concurrency per critical function so noisy neighbors don’t starve payment webhooks.
  • Use structured JSON logs and X-Ray (or OpenTelemetry) from day one—scatter print debugging doesn’t scale across hundreds of invocations.
  • Package dependencies in container images when startup time or native libs demand it.

Pair Lambda with DynamoDB or Aurora Data API thoughtfully; connection storms from naive SQL pools in autoscaled functions remain a common pitfall in corporate migrations.