AWS Lambda Cheat Sheet Hub

AWS Lambda is the foundation of serverless computing on AWS — and one of the most heavily tested services across SAA-C03, DVA-C02, SAP-C02, and DOP-C02. Understanding Lambda deeply means understanding not just the service itself, but how it fits into the broader AWS ecosystem: when to use it over ECS, how it integrates with API Gateway, SQS, SNS, EventBridge, Step Functions, and DynamoDB, and what its hard limits mean for your architecture.

The Lambda service cheat sheet covers the essentials: execution environments, cold start behavior, memory and timeout limits (up to 15 minutes, 10 GB RAM), concurrency models (reserved, provisioned), supported runtimes, deployment packages vs container images, and the IAM execution role model. It also covers the key exam traps — Lambda@Edge vs CloudFront Functions, SnapStart for Java, function URLs vs API Gateway, and the 1000 concurrent execution default account limit.

Beyond the service sheet, the comparison cheat sheets put Lambda in context. Lambda vs ECS vs EKS vs Fargate resolves the most common serverless compute decision — when stateless functions make sense vs long-running containers. EventBridge vs SNS vs SQS as Lambda triggers is another classic exam scenario that trips up even experienced architects.

From an architecture perspective, Lambda is the glue of event-driven systems on AWS. It connects storage events (S3 triggers), database streams (DynamoDB Streams, Kinesis), API calls (API Gateway, ALB), scheduled jobs (EventBridge Scheduler), and workflow orchestration (Step Functions). The serverless architecture patterns guide covers all of these integration models with decision frameworks.

For exam preparation: focus on Lambda concurrency (burst limit, account limit, reserved vs provisioned), the invocation models (synchronous, asynchronous, poll-based), destination configurations, error handling with DLQs, and the VPC integration trade-offs. These topics appear on almost every SAA-C03 and DVA-C02 exam.