Serverless Framework + express, mongoDB atlas sample

config.js

module.exports.getConfig = () => {
//console.log("IS_OFFLINE= ", process.env.IS_OFFLINE);
  return {
    MONGODB_URL: '',
    MONGODB_DB_NAME: 'test',
    DELETE_TOKEN_EXPIRE_MIN : 120,  // min (ex: 120)    
  };
};

index.js

var express = require('express');
var router = express.Router();
const Config = require('../config');
const LibMongo = require('../lib/LibMongo');

/* GET home page. */
router.get('/', function(req, res, next) {
  console.log("root");
  res.json({ret: 'root OK'});
});
router.get('/test', function(req, res, next) {
  console.log("test");
  res.json({ret: 'OK'});
});
router.get('/test2',async function(req, res, next) {
//console.log("test2");
  const cfg = Config.getConfig();
//console.log( cfg.MONGODB_URL );
//console.log( cfg.MONGODB_DB_NAME );
  const client = await LibMongo.getClient();
  const db = client.db(cfg.MONGODB_DB_NAME);
  const collection = db.collection("tasks");
  const items = await collection.find({}).sort({created_at: -1}).toArray();
  client.close();
//console.log(items);
  res.json({data: items});
});


module.exports = router;

LibMongo.js

'use strict';
const MongoClient = require('mongodb').MongoClient;
const Config = require('../config.js');
const CFG = Config.getConfig();
//console.log( CFG.MONGODB_URL );
//console.log( CFG.MONGODB_DB_NAME );
const URI = CFG.MONGODB_URL + "?retryWrites=true&w=majority";
const DbName = CFG.MONGODB_DB_NAME;
module.exports.getClient =  async () => {
//  console.log("IS_OFFLINE= ", process.env.IS_OFFLINE);
  try{
    //console.log(process.env.MONGODB_DB_NAME);
    const client = await new MongoClient(URI, { useNewUrlParser: true, useUnifiedTopology: true });
    await client.connect();
    return client
  } catch (err) {
    console.log(err);
    throw new Error('Error, getClient');
  }
};
/*
module.exports.getArrayWhere = async  (collectionName , where) => {
  console.log("IS_OFFLINE= ", process.env.IS_OFFLINE);
  try{
    let client = await MongoClient.connect(URL);
    const db = client.db(DbName);
    const collection = db.collection(collectionName);
    const items = await collection.find(where).sort({created_at: -1}).toArray()
    client.close();
    return items    
  } catch (err) {
    console.log(err);
    throw new Error('Error, getClient');
  }
};
*/