Create a Basic Framework with Express (Part 1)

We will be using Docker, Node 18, MySQL 8, and Redis. Following Setting Up Node App using Docker post express, nodemon, dotenv packages should be installed.

In this application, we will not be writing a rest app, it will be a basic full stack framework. Packages will be installed once we reach the point where we need to use them.

Create Project Structure

node_modules
public
controllers
database
helpers
middlewares
routes
storage
views

Setup Logging

Install Winston
```
npm install winston
```
To be able to write daily logs instead of a single log, install Winston Daily Rotate File
```
npm install winston-daily-rotate-file
```

Create a logger.js helper in helpers directory

We want to have it log into daily log files of max size of 1GB and will be kept for 10 days.

const winston = require('winston')
const { format } = winston
const { combine, timestamp, printf, splat } = format
require('winston-daily-rotate-file')

const dailyTransport = new winston.transports.DailyRotateFile({
  // file name format
  filename: 'application-%DATE%.log',
  datePattern: 'YYYY-MM-DD',
  zippedArchive: true,
  // limit each log to 1GB
  maxSize: '1g',
  // format the log
  format: combine(
      timestamp(),
      splat(),
      printf((info) => {
          return `[${info.timestamp}] ${info.level}: ${info.message}`
      })
  ),
  level: 'info',
  // save logs into storage/logs
  dirname: 'storage/logs',
  // save logs for 10 days
  maxFiles: '10d',
})

const logger = winston.createLogger({
  transports: [dailyTransport],
})

module.exports = logger

Create a errorHandler.middleware.js helper in middlewares directory

Log the error and send a response to the user

// import logger helpers
const loggerx = require('../helpers/logger')

const errorHandler = {
 // log the error
 logger: (error, request, response, next) => {
     loggerx.error(`${error.message} %o`, error)
     next(error) // calling next middleware
 },

 responder: (error, request, response, next) => {
     const status = error.statusCode || 500
     // send status and error message
     return response.status(status).send(error.message)
 }
}
module.exports = errorHandler;

Add the error handler middleware to index.js and test it out!

 ...
 const express = require('express')
 const app = express()

 // import the logger helper so we can test the logging
 const logger = require('../helpers/logger')
 // import the error handler
 const errorHandler = require('./middlewares/errorHandler.middleware.js')

 ...

 // Cause an error
 app.get('/error', async (req, res, next) => {
     try {
         let error = new Error('This is a major issue!!')
         error.statusCode = 500
         throw error
     } catch (error) {
         return next(error)
     }
 })

 // Just logging
 app.get('/log', async (req, res, next) => {
     logger.info('hello from /log')
     res.send('hello')
 })

 // log the error
 app.use(errorHandler.logger)
 // send error to user
 app.use(errorHandler.responder)

 ...

Go to localhost:3000/error and localhost:3000/log, the log file can be found in storage/logs (example below)

[2023-03-20T00:41:29.652Z] error: This is a major issue!! Error: This is a major issue!!
  at /app/index.js:28:25
  at Layer.handle [as handle_request] (/app/node_modules/express/lib/router/layer.js:95:5)
  at next (/app/node_modules/express/lib/router/route.js:144:13)
  at Route.dispatch (/app/node_modules/express/lib/router/route.js:114:3)
  at Layer.handle [as handle_request] (/app/node_modules/express/lib/router/layer.js:95:5)
  at /app/node_modules/express/lib/router/index.js:284:15
  at Function.process_params (/app/node_modules/express/lib/router/index.js:346:12)
  at next (/app/node_modules/express/lib/router/index.js:280:10)
  at expressInit (/app/node_modules/express/lib/middleware/init.js:40:5)
  at Layer.handle [as handle_request] (/app/node_modules/express/lib/router/layer.js:95:5) {
[stack]: 'Error: This is a major issue!!\n' +
  '    at /app/index.js:28:25\n' +
  '    at Layer.handle [as handle_request] (/app/node_modules/express/lib/router/layer.js:95:5)\n' +
  '    at next (/app/node_modules/express/lib/router/route.js:144:13)\n' +
  '    at Route.dispatch (/app/node_modules/express/lib/router/route.js:114:3)\n' +
  '    at Layer.handle [as handle_request] (/app/node_modules/express/lib/router/layer.js:95:5)\n' +
  '    at /app/node_modules/express/lib/router/index.js:284:15\n' +
  '    at Function.process_params (/app/node_modules/express/lib/router/index.js:346:12)\n' +
  '    at next (/app/node_modules/express/lib/router/index.js:280:10)\n' +
  '    at expressInit (/app/node_modules/express/lib/middleware/init.js:40:5)\n' +
  '    at Layer.handle [as handle_request] (/app/node_modules/express/lib/router/layer.js:95:5)',
[message]: 'This is a major issue!!',
statusCode: 500
}
[2023-03-20T00:41:59.271Z] info: hello from /log