morgan custom format example

index.js

const express = require('express');
const fs = require('fs');
const path = require('path');
const morgan = require('morgan');

const morganFormat = (tokens, req, res) => (
  JSON.stringify({
    'remote-addr': tokens['remote-addr'](req),
    'remote-user': tokens['remote-user'](req),
    'date': tokens.date(req, res, 'iso'),
    method: tokens.method(req, res),
    url: tokens.url(req, res),
    status: tokens.status(req, res),
    'content-length': tokens.res(req, res, 'content-length'),
    'response-time-ms': tokens['response-time'](req, res),
    referrer: tokens.referrer(req)
  })
);

const accessLogStream = fs.createWriteStream(path.join(__dirname, 'access.log'), {flags: 'a'});
const app = express();
app.use(morgan(morganFormat, { stream: accessLogStream }));

let dict = {
  hello: 'greeting',
  greeting: 'acknowledgement',
  cat: 'feline',
  feline: 'carnivore',
  placental: 'mammal'
};

app.get('/', (req, res) => res.send('Hello World!'));

app.get('/get/:key', (req, res) => {
  const key = req.params.key;
  const value = dict[key];
  if (!value) {
    res.status(404).send(key + ' not found.');
    return;
  }
  res.send(value);
});

app.post('/post/:key/:value', (req, res) => {
  const key = req.params.key;
  const value = req.params.value;
  if ((!key) || (!value)) {
    res.status(500).send('Bad request.');
    return;
  }
  dict[key] = value;
  res.status(200).send('OK');
});

app.use(express.static('public'));

app.listen(3000, () => console.log('Example app listening on port 3000!'));

package.json

{
  "name": "morgan-custom-format-example",
  "version": "1.0.0",
  "description": "morgan custom format example",
  "main": "index.js",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1"
  },
  "author": "[email protected]",
  "license": "ISC",
  "dependencies": {
    "express": "^4.16.3",
    "morgan": "^1.9.0"
  }
}