How can I call my AWS Lambda function URL via a custom domain?

Question

I have created an AWS Lambda with the new function URL feature enabled.

Since the URL isn't that easy to remember, I would like to create a Route 53 alias like lambda.mywebsite.com.

There is no Route 53 alias for Lambda function URLs in the drop-down menu for aliases in Route 53.

How can I call my AWS Lambda function URL via a custom domain?

Is a CNAME record the way to go?

Answer 1

How can I call my AWS Lambda function URL via a custom domain?

If you must use an AWS Lambda function URL, fronting it with a CloudFront distribution with your desired custom domain name is the only way currently.

There is no support currently for a Route 53 alias record, as the Host header must be set to the Lambda function URL domain. If the Host header does not exist, HTTP 400 Bad Request is returned & if it does exist but is not the correct value, HTTP 403 Forbidden is returned.

They are meant to be the simplest & fastest way to invoke your Lambda functions via a public endpoint without using other AWS services like API gateway, so a native lack of support for a custom domain name makes sense.

Answer 2

I tried the same once lambda url feature was out. Following are the steps:

1. Create a cloudfront distribution with lambda url as https endpoint, add the domain name in the alternate domain name field.
2. Create a A record for the domain in Route53 and point it to the cloudfront distribution.

Note: If in case you haven't added domain certificate in step1 then the cloudfront option in step2 wont show any value to select.