AWS Lambda: Event-Driven Serverless Guide

AWS LAMBDA

Event-driven serverless compute that scales automatically with zero infrastructure management.

01. The Ingredients

What triggers a Lambda function?

Trigger code when a file is uploaded, modified, or deleted in an S3 bucket.

Create REST or HTTP APIs that trigger Lambda functions for backend logic.

Capture table-level changes (Streams) to trigger downstream processing.

Schedule events (CRON) or react to system health alarms automatically.

The lifecycle of a serverless request

1. Invoke

The event triggers a container spin-up (Cold Start) or uses an existing one (Warm Start).

2. Execute

Code runs in a micro-VM. Memory is allocated from 128MB to 10GB. CPU scales with memory.

3. Destroy

Once the task is complete, the environment is eventually frozen and purged. You pay only for execution time.

Know your boundaries to avoid bottlenecks

The number of simultaneous requests your function can handle.

Default Limit: 1,000 per Region

Maximum time a single execution is allowed to run before being killed.

Max Duration: 15 Minutes

The maximum size of the request and response data (Invocation payload).

Sync / Async: 6MB / 256KB