serverless-offline/src/events/authValidateContext.js

Emulate AWS λ and API Gateway locally when developing your Serverless project

import Boom from "@hapi/boom"
import { log } from "../utils/log.js"

const { entries, fromEntries, values } = Object

function internalServerError(message) {
  const errorType = "AuthorizerConfigurationException"

  const error = Boom.internal()

  error.output.headers["x-amzn-ErrorType"] = errorType
  error.output.payload.error = errorType
  error.output.payload.message = message

  return error
}

function isValidContext(context) {
  return values(context).every(
    (value) =>
      typeof value === "boolean" ||
      typeof value === "number" ||
      typeof value === "string",
  )
}

function transform(context) {
  return fromEntries(
    entries(context).map(([key, value]) => [key, String(value)]),
  )
}

export default function authValidateContext(context, authFunName) {
  if (typeof context !== "object") {
    return internalServerError("Authorizer response context must be an object")
  }

  if (!isValidContext(context)) {
    const error =
      "Authorizer response context values must be of type string, number, or boolean"

    log.notice(
      `Detected invalid value types returned in authorizer context: (λ: ${authFunName}). ${error}. ` +
        "More info: https://docs.aws.amazon.com/apigateway/latest/developerguide/api-gateway-lambda-authorizer-output.html",
    )

    return internalServerError(error)
  }

  return transform(context)
}