Firebase function serving restify server if production(else just start server onj)

express_server_obj_exposed_to_firebase.js

const server = require(`./src/server`);

process.env.NODE_ENV === "DEV" ?
  /**
   *  If dev environment, run express server for local debugging.
   */

  server.listen(process.env.PORT || 3000) :
  /**
   *  Creates a function instance and with a specific specs.
   *  Serve to FireBase Express server obj.
   */
  exports[require("./package").name] = require("firebase-functions")
    .region("europe-west1")
    .runWith({ timeoutSeconds: 300, memory: "2GB" }).https.onRequest(server);