Lambda

ELI5 — The Vibe Check

AWS Lambda is where you upload a function and AWS runs it when something happens — an HTTP request, a file upload, a database change. You pay only for the milliseconds it runs. No server to manage, no idle costs. It's serverless magic and the poster child of FaaS.

Real Talk

AWS Lambda is a serverless compute service that runs code in response to events (HTTP via API Gateway, S3 uploads, DynamoDB streams, scheduled triggers). It auto-scales from zero to thousands of concurrent executions, charges per 100ms of runtime, and supports multiple runtimes (Node.js, Python, Go, etc.).

Show Me The Code

// Lambda triggered by API Gateway
export const handler = async (event) => {
  const body = JSON.parse(event.body);
  const result = await processOrder(body);
  
  return {
    statusCode: 200,
    headers: { 'Content-Type': 'application/json' },
    body: JSON.stringify(result)
  };
};

When You'll Hear This

"The image resize runs as a Lambda triggered by the S3 upload." / "Lambda cold starts are adding 2 seconds of latency."