Lesson 17 / 26

API Gateway + Lambda Pattern

Q: What is a key benefit of the API Gateway + Lambda pattern for a low-traffic API?

You pay roughly per request with no idle server cost. Lambda's pricing is per invocation/duration, so a low-traffic API isn't paying for idle capacity.

A serverless backend: HTTP in, functions out.

The pattern

API Gateway exposes an HTTP endpoint, validates and routes each request, then invokes a Lambda function to produce the response — a whole REST API with no servers to manage.

Why teams use it

It fits spiky or low-traffic APIs well: you get automatic scaling, built-in auth integrations, and pay only per request — no idle EC2 fleet running 24/7.

Watch cold starts and timeouts

A Lambda not called recently can have a cold start delay, and every function has a max execution timeout. Not ideal for very long-running or latency-critical hot paths.

Quick check: What is a key benefit of the API Gateway + Lambda pattern for a low-traffic API?

You pay for servers running 24/7 regardless of traffic
You pay roughly per request with no idle server cost
It removes the need for authentication

Answer

You pay roughly per request with no idle server cost — Lambda's pricing is per invocation/duration, so a low-traffic API isn't paying for idle capacity.