fix: fixed 500 error when db connection failed

- DB가 접속되지 않을 때 서버를 종료하여 api연결 시 실패 원인을 모르는
것보다, 500 에러를 출력하여 왜 처리가 안되는지 명확히 표시하여
클라이언트내에서 다른 처리가 가능하도록 하기 위해 변경
- 불필요한 파일 제거

apis/product/app.js

@@ -1,22 +1,18 @@
 import express from 'express';
 import cookieParser from 'cookie-parser';
 import logger from 'morgan';
-import dotenv from 'dotenv';
 import cors from 'cors';
-import db from './db';
 import indexRouter from './routes/index';
 import productRouter from './routes/product';
 import infoRouter from './routes/info';
 import secretRouter from './routes/secret';
 import etagGenerator from './routes/middleware/etag-generator';
-
-dotenv.config();
-db().catch(() => {
-  process.exit();
-});
+import { dbConnect } from './config';
 
 const app = express();
 
+app.use(dbConnect());
+
 app.use(cors());
 app.use(logger('dev'));
 app.use(express.json());
@@ -32,9 +28,8 @@ app.use('/secrets', secretRouter);
 
 // eslint-disable-next-line no-unused-vars
 app.use((err, req, res, next) => {
-  const message = err.message.split('|')[0].trim();
   res.status(err.status || 500);
-  res.json(message);
+  res.json(err.message);
 });
 
 module.exports = app;

apis/product/bin/www.js

@@ -4,6 +4,7 @@
  * Module dependencies.
  */
 
+var dotenv = require('dotenv').config();
 var app = require('../app');
 var debug = require('debug')('template:server');
 var http = require('http');

apis/product/config/index.js

@@ -1,3 +1,26 @@
+import mongoose from 'mongoose';
+
+export const dbConnect = () => {
+  const options = {
+    useNewUrlParser: true,
+    useUnifiedTopology: true,
+    keepAlive: false,
+  };
+  let errorMessage;
+  mongoose.connect(`${process.env.MONGO_URL}`, options, (err) => {
+    if (err) {
+      errorMessage = err.toString();
+    }
+  });
+  return (req, res, next) => {
+    if (errorMessage) {
+      next({ status: 500, message: errorMessage });
+    } else {
+      next();
+    }
+  };
+};
+
 export const mongoosasticSettings = (process.env.NODE_ENV === 'test') ? {} : {
   hosts: process.env.ELASTICSEARCH,
   port: process.env.ESPORT,