Provides AWS Lambda integration patterns for TypeScript with cold start optimization. Use when creating or deploying TypeScript Lambda functions, choosing between NestJS framework and raw TypeScript approaches, optimizing cold starts, configuring API Gateway or ALB integration, or implementing serve

AWS Lambda TypeScript Integration Patterns for creating high performance AWS Lambda functions in TypeScript with optimized cold starts. Overview Two approaches for TypeScript Lambda: 1. NestJS Framework Dependency injection, modular architecture, larger bundle (100KB+) 2. Raw TypeScript Minimal overhead, smaller bundle (<50KB), maximum control Both support API Gateway and ALB integration. When to Use Creating new Lambda functions in TypeScript Optimizing cold start performance Choosing between NestJS and minimal TypeScript Configuring API Gateway or ALB integration Setting up CI/CD for TypeScript Lambda Instructions 1. Choose Your Approach Approach Cold Start Bundle Size Best For Complexity NestJS < 500ms Larger (100KB+) Complex APIs, enterprise apps, DI needed Medium Raw TypeScript < 100ms Smaller (< 50KB) Simple handlers, microservices, minimal deps Low 2. Project Structure NestJS Structure Raw TypeScript Structure 3. Implementation Examples See the [References]( references) section for detailed implementation guides. Quick examples: NestJS Handler: Raw TypeScript Handler: Core Concepts Cold Start Optimization TypeScript cold start depends on bundle size and initialization code. Key strategies: 1. Lazy Loading Defer heavy imports until needed 2. Tree Shaking Remove unused code from bundle 3. Minification Use esbuild or terser for smaller bundles 4. Instance Caching Cache initialized services between invocations See [Raw TypeScript Lambda](references/raw typescript lambda.md cold start optimization) for detailed patterns. Connection Management Create clients at module level and reuse: Environment Configuration Best Practices Memory and Timeout Configuration Memory : Start with 512MB for NestJS, 256MB for raw TypeScript Timeout : Set based on cold start + expected processing time NestJS: 10 30 seconds for cold start buffer Raw TypeScript: 3 10 seconds typically sufficient Dependencies Keep package.json minimal: Error Handling Return proper HTTP codes with structured errors: Logging Use structured logging for CloudWatch Insights: Deployment Options Quick Start Serverless Framework: AWS SAM: Deployment Validation Pre deploy checks: 1. Run npm test verify all tests pass 2. Run npm run build confirm TypeScript compiles without errors 3. Verify bundle size < 50MB (unzipped) 4. Run serverless invoke local or sam local invoke test locally Post deploy verification: 1. Run serverless invoke or aws lambda invoke verify handler executes 2. Test API endpoint via curl or Postman 3. Check CloudWatch logs for errors 4. Verify cold start time meets SLA For complete deployment configurations including CI/CD, see [Serverless Deployment](references/serverless deployment.md). Constraints and Warnings Lambda Limits Deployment package : 250MB unzipped maximum (50MB zipped) Memory : 128MB to 10GB Timeout : 15 minutes maximum Concurrent executions : 1000 default (adjustable) Environment variables : 4KB total size TypeScript Specific Considerations Bundle size : TypeScript compiles to JavaScript; use bundlers to minimize size Cold start : Node.js 20.x offers best performance Dependencies : Use Lambda Layers for shared dependencies Native modules : Must be compiled for Amazon Linux 2 Common Pitfalls 1. Importing heavy libraries at module level Defer to lazy loading if not always needed 2. Not bundling dependencies Include all production dependencies in the package 3. Missing type definitions Install @types/aws lambda for proper event typing 4. No timeout handling Use context.getRemainingTimeInMillis() for long operations Security Considerations Never hardcode credentials; use IAM roles and environment variables Input Validation for Event Data : All incoming event data (API Gateway request bodies, S3 event objects, SQS message bodies) is untrusted external content; always validate and sanitize before processing to prevent injection attacks Content Sanitization : When processing S3 objects or SQS message payloads, treat the content as untrusted third party data; apply appropriate validation, schema checks, and sanitization before acting on it Validate all input data Use least privilege IAM policies Enable CloudTrail for audit logging Sanitize logs to avoid leaking sensitive data References For detailed guidance on specific topics: [NestJS Lambda](references/nestjs lambda.md) Complete NestJS setup, dependency injection, Express/Fastify adapters [Raw TypeScript Lambda](references/raw typescript lambda.md) Minimal handler patterns, bundling, tree shaking [Serverless Config](references/serverless config.md) Serverless Framework and SAM configuration [Serverless Deployment](references/serverless deployment.md) CI/CD pipelines, environment management [Testing](references/testing.md) Jest, integration testing, SAM Local Examples Example 1: Create a NestJS REST API Input: Create a TypeScript Lambda REST API using NestJS for a todo application Process: 1. Initialize NestJS project with nest new 2. Install Lambda dependencies: @codegenie/serverless express , aws lambda 3. Create lambda.ts entry point with Express adapter 4. Configure serverless.yml with API Gateway events 5. Deploy with Serverless Framework Validation: Run serverless invoke local f api verify handler works Check bundle size < 250MB Test deployed endpoint returns 200 OK Output: NestJS project with REST API, DynamoDB integration, deployment config Example 2: Create a Raw TypeScript Lambda Input: Create a minimal TypeScript Lambda function with optimal cold start Process: 1. Set up TypeScript project with esbuild 2. Create handler with proper AWS types 3. Configure minimal dependencies 4. Set up SAM or Serverless deployment 5. Optimize bundle size with tree shaking Validation: Run sam local invoke test locally before deploying Verify bundle < 50KB with du sh dist/ Confirm cold start < 100ms via CloudWatch Output: Minimal TypeScript Lambda, bundle < 50KB, cold start < 100ms Example 3: Deploy with GitHub Actions Input: Configure CI/CD for TypeScript Lambda with SAM Process: 1. Create GitHub Actions workflow 2. Set up Node.js environment 3. Run tests with Jest 4. Bundle with esbuild 5. Deploy with SAM Validation: Verify CI pipeline runs npm test successfully Confirm sam validate passes in pipeline Check CloudFormation stack created successfully Output: GitHub Actions workflow, multi stage pipeline, test automation Version Version: 1.0.0

aws-lambda-typescript-integration