Serverless

AWS Lambda

Run code without provisioning servers.

Overview

Lambda runs your code in response to events (HTTP, queue messages, file uploads, schedules). You pay per invocation and GB-seconds of execution; no servers to patch.

When to use it

Event-driven glue code between AWS services
Lightweight APIs behind API Gateway
Scheduled jobs (cron via EventBridge)
Short-lived test helpers and webhooks

Setup

Console → Lambda → Create function. Choose runtime (Node 20, Python 3.12, etc).
Define an execution role (IAM) with least-privilege policies.
Set memory (128 MB – 10 GB) and timeout (max 15 min).
Add a trigger (API Gateway, S3, SQS, EventBridge…).
Optionally enable VPC access if calling private resources.

How to use

Minimal Node.js handler

export const handler = async (event) => {
  return { statusCode: 200, body: JSON.stringify({ ok: true, event }) };
};

Deploy with AWS CLI

zip -r fn.zip index.mjs
aws lambda update-function-code --function-name my-fn --zip-file fileb://fn.zip

QA use cases

Webhook receiver that posts CI results into Slack / Teams.
On S3 upload of a test report, generate a summary and email QA leads via SES.
Scheduled API health-check that pings endpoints and writes pass/fail metrics to CloudWatch.