You can do the same thing with Lambda @ Edge and CloudFront for .60 per million requests and there is a free tier. (https://aws.amazon.com/lambda/pricing/)
Yeah I just wanted to point out like the authors whose post I copied here that the way of going serverless taken by the story author was probably not ideal.
Lambdas @ edge don’t either. There are different optimizations than regular lambdas and you wouldn’t use a heavyweight environment and of course they wouldn’t be running attached to a network.