OAuth 2.0 + Lambda + API Gateway

Question

Ok I do some reaserch and I try once more explain what I am looking for.
So my question is can I make OAuth provider server using Lambda and API gateway? I didn't found any solution like this, and I don't even know how to start so any ideas are valuable.
And then I want to use API custom authentication to validade my bearer token.

I try to be specific as I can: I have my application where I store my log users. I want to OAuth 2.0 authorization code grant flow using only Lambda and API Gateway (something like Google oAuth but my app want to be an authentication provider). I found couple solutions like this: https://www.authlete.com/documents/article/custom_authorizer/index but I want to use my own authorization server implementation, and I don't want to specific in Lambda auth impl. api_key and secret_key. So there are my questions: 1. Can I make my own authorization server using only Lambda and API gateway? (I know there is a implementation in Spring but for now I want serwerless solution) 2. If I can I will be pleased for any tips because I really stuck.
There is a possibility that in my reasoning are mistakes.

Answer 1

In API Gateway you can create custom authorizers to be invoked before the API method is executed. Normally you can create a Lambda function to receive the authentication details and return a Policyt Document authorizing or denying the API method execution.

You can create a Lambda to make the OAuth provider authentication and generate the Policy Document, based on authentication flow. You can get more information here .