4 ways of executing Lambda function via HTTP endpoint - a comparison

#lambda #serverless #apigateway #aws

Recent release of Lambda Function URLs is a great reason to write up a small summary describing possible ways of executing Lambda functions over HTTP endpoints.

There are four ways to invoke a Lambda function over HTTP:

API Gateway REST API
API Gateway HTTP API
Application Load Balancer
NEW Lambda Function URLs

Once again, AWS released new functionality, but it's up to us how, and more importantly, when we are going to use it. I hope this brief comparison will give you a head start, and make it easier to decided which option to select.

Comparison table

	API GW REST	API GW HTTP	ALB	Lambda URL
Authentication	AWS_IAM, Custom authorizers	AWS_IAM, Custom authorizers, JWT	Social and corporate Identity Providers	AWS_IAM
CORS	✅	✅	CORS headers need to be provided in a response from Lambda function.	✅
Custom domain names	✅	✅	✅	❌
Timeout [seconds]	29	30	60 default, max 4000 (The load balancer waits until your Lambda function responds or times out.)	Equal to Lambda's timeout, max 900
Throttle quota	10,000 requests per second (RPS) per region shared among other resources	10,000 requests per second (RPS) per region shared among other resources
Pricing	First 333 million = $3.5	First 300 million = $1.0	Complex to explain, cheaper than API GW over 500,000 requests per day	Free, CloudFront proxying to Lambda URL = ~ $1.0 to $1.2
Payload size	API GW 10 MB, but Lambda's is 6 MB.	API GW 10 MB, but Lambda's is 6 MB	1 MB	6 MB
Validation	✅	❌	❌	❌
Data transformations	✅	❌	❌	❌
API Proxy	✅	✅	❌	✅
API caching	✅	❌	❌	❌
Private endpoints	✅	❌	❌	❌
Lambda alias support	✅	✅	✅ (via target groups)	✅
Additional info			Not serverless. AWS WAF supported	Custom domain are not supported but can be mapped via CloudFront
Short summary	Expensive but feature-rich	Cheaper and faster. Probably you should use that in enterprise software.	Makes sense for huge scale because of pricing.	Free, simple and easy. Tiny projects & automations.

Disclaimer

This summary was created to the best of my knowledge. If you found some mistakes, or think that something important should be added that to it, please let me know.