AWS Lambda & Serverless Compute

Event-driven execution, triggers, cold starts, and API Gateway integration

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AWS Lambda runs code in response to events and automatically manages the underlying compute infrastructure, scaling from zero to thousands of parallel executions with zero server administration.

How Serverless Functions Work

Pay-per-Execution: You pay only for compute time consumed (measured in milliseconds) with zero charges when code is idle.

Event Triggers: S3 uploads, DynamoDB table modifications, SQS queue messages, or HTTP requests via Amazon API Gateway.

Cold Starts: The initial latency when a Lambda container is booted up for the first time or after a period of dormancy.

Stateless Execution: Lambda instances are ephemeral; state must be persisted in databases like DynamoDB or Redis.

Node.js Lambda Handler with API Gateway Response

Try It Yourself »

// Lambda Function Entrypoint (index.mjs)
export const handler = async (event) => {
  console.log("Received event:", JSON.stringify(event));

  const responseBody = {
    message: "Hello from Codexia Serverless Lambda!",
    timestamp: new Date().toISOString()
  };

  return {
    statusCode: 200,
    headers: {
      "Content-Type": "application/json",
      "Access-Control-Allow-Origin": "*"
    },
    body: JSON.stringify(responseBody)
  };
};

Standard event/context interface for serverless functions.

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Test Yourself With Exercise

+15 XP

What is the primary pricing model for AWS Lambda compute?

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