Architecting a Node.js serverless backend with AWS Lambda and cold start optimization
Scenario
Context A serverless API built on AWS Lambda experiences cold start latencies of 3-5 seconds on the first request, making the application feel broken to users. The Problem The Lambda functions import heavy dependencies at the module level and initialize database connections inside the handler, causing maximum cold start overhead. Constraints Move database connection initialization outside the handler to reuse across warm invocations. Use Lambda layers to share common dependencies across functions. Implement provisioned concurrency for latency-sensitive endpoints. Measure cold start reduction with before-and-after metrics. Expected Deliverable A Node.js Lambda architecture with optimized cold starts via connection reuse, shared layers, and provisioned concurrency, with documented latency improvements.