Client Certificate Auth to Node.js server example?

Hey guys , im trying to setup Client Certificate Auth in AWS API Gateway and authenticate it at nodejs server. But there are no good examples. Has anyone here implemented it ?

https://aws.amazon.com/blogs/compute/propagating-valid-mtls-client-certificate-identity-to-downstream-services-using-amazon-api-gateway/|https://aws.amazon.com/blogs/compute/propagating-valid-mtls-client-certificate-identity-to-downstream-services-using-amazon-api-gateway/

Very generic but official

what problem are you running into, hopefully you don’t need client certificate auth