As of Meteor 6.0, now we need to use Npm.require() instead. Additionally, we need to declare the module as global variables, since Meteor now has file-level scope.
var path = Npm.require('path');
var fs = Npm.require('fs');
var base = path.resolve('.');
var isBundle = fs.existsSync(base + '/bundle');
var modulePath = base + (isBundle ? '/bundle/static' : '/public') + '/node_modules';
MODULE_NAME = Npm.require(modulePath + '/MODULE_NAME'); // NOTE, this is going to be a global variable