Rocket.Chat/apps/meteor/app/lib/server/startup/robots.js

import { Meteor } from 'meteor/meteor';
import { WebApp } from 'meteor/webapp';

import { settings } from '../../../settings/server';

Meteor.startup(function () {
	return WebApp.connectHandlers.use('/robots.txt', function (req, res /* , next*/) {
		res.writeHead(200);
		res.end(settings.get('Robot_Instructions_File_Content'));
	});
});