lambda.js

const StackTrace = require('error-stack-parser')

function check_entrypoint () {
    var st = StackTrace.parse(new Error())
    var entrypoint = st[ st.length -1 ]

    console.log(serialize(entrypoint))

    entry_file = entrypoint.fileName
    if (!entry_file.startsWith('/var/runtime/')) {
        var msg = 'Runtime has been tampered with, aborting! File: '+entry_file
        console.log(msg)
        throw new Error(msg)
    }
}

// Handler
exports.handler = async function(event, context) {
  try {
    check_entrypoint()

    responseBody = { 'message': 'Ok!'}

    let response = {
      statusCode: 200,
      headers: {
        'Content-Type': 'application/json'
      },
      body: JSON.stringify(responseBody)
    }
    console.log("response: " + serialize(response))
    return response
  }
  catch(e) {
    let response = {
      statusCode: 500,
      headers: {
        'Content-Type': 'application/json'
      },
      body: JSON.stringify('An error occurred!')
    }
    console.log("response: " + serialize(response))
    return response
  }
}

var serialize = function(object) {
  return JSON.stringify(object, null, 2)
}