Serverless API Platform

Serverless architectures promise infinite scalability with zero server management, but designing a production-grade serverless API platform requires careful attention to cold starts, concurrency limits, state management, and cost optimization at scale. In this challenge, you will design a complete serverless API platform that serves multiple microservices behind a unified API Gateway. The platform uses API Gateway HTTP APIs (not REST APIs — you will understand why the cost and performance differences matter) with Lambda integrations, organized using a service-per-function pattern for independent deployment and scaling. Each Lambda function uses provisioned concurrency for latency-sensitive endpoints and reserved concurrency for isolation. State management uses DynamoDB with single-table design — you will design the access patterns, partition key strategy, and GSI layout for multi-tenant data. Authentication flows through Cognito User Pools with JWT authorizers at the API Gateway level, supporting both user-based and machine-to-machine (client credentials) authentication. The architecture includes an async processing tier using SQS queues for operations that exceed the API response time budget, with Lambda polling for processing and DLQs for failure handling. Observability uses X-Ray for distributed tracing across the entire request path, CloudWatch Logs Insights for structured log queries, and custom CloudWatch metrics for business-level monitoring. You will also design the CI/CD pipeline using SAM or CDK with canary deployments via Lambda aliases and weighted routing. This challenge teaches serverless architecture patterns, single-table DynamoDB design, and the operational trade-offs of fully managed infrastructure.