blogpost_crossAccountRole_registerUser.js

const response = require('cfn-response-promise')
const util = require('util')

async function replyToResourceRequest(event, context) {
  return await response.send(event, context, response.SUCCESS, {});
}

async function saveUserDetailsToDb(AccountId, RoleArn, ExternalID) {
  console.log(`Persisting the user info to the database ${AccountId}, ${RoleArn}, ${ExternalID}`)
  // do some db things...
}

module.exports.handler = async (event, context) => {

  console.log(`Got SNS message: ${util.inspect(event, { depth: 10 })}`)
  const snsMessage = event.Records[0].Sns
  const resourceEvent = JSON.parse(snsMessage.Message)

  let AccountID, RoleArn, ExternalID
  ({ AccountID, RoleArn, ExternalID } = resourceEvent.ResourceProperties)

  await saveUserDetailsToDb(AccountID, RoleArn, ExternalID)
  await replyToResourceRequest(resourceEvent, context)

}