An AWS lambda authorizer that work with google access token

aws-lambda-authorizer-google.js

const axios = require("axios");

exports.handler = async event => {
  const token = event.authorizationToken;
  console.log(`Received token`, token);

  let googleAuthRes;
  try {
    googleAuthRes = await axios.get(
      `https://www.googleapis.com/oauth2/v1/tokeninfo?access_token=${token}`
    );
  } catch (err) {
    console.error("Couldn't validate token", err);

    return Promise.reject("Unauthorized");
  }

  return Promise.resolve(
    generatePolicy(
      googleAuthRes.data.user_id,
      "Allow",
      event.methodArn,
      googleAuthRes.data
    )
  );
};

const generatePolicy = (principalId, effect, resource, context = {}) => {
  const authResponse = { principalId, context };

  if (effect && resource) {
    authResponse.policyDocument = {
      Version: "2012-10-17",
      Statement: [
        {
          Action: "execute-api:Invoke",
          Effect: effect,
          Resource: resource
        }
      ]
    };
  }

  return authResponse;
};