Morgan, Winston configuration for Express

logger.js

const winston = require('winston')
const morgan = require('morgan')

const { name: packageName } = require('./package')
const {
  LOG_CONSOLE,
  LOG_FILE,
  LOG_LEVEL,
  NODE_ENV
} = process.env

const format = winston.format.combine(
  winston.format.timestamp(),
  winston.format.errors({ stack: true }),
  NODE_ENV !== 'production' ? winston.format.simple() : winston.format.json()
)

const transports = [
  LOG_CONSOLE === 'true' && new winston.transports.Console(),
  LOG_FILE === 'true' && new winston.transports.File({ filename: `${packageName}.log` })
].filter(Boolean)

const logger = winston.createLogger({
  defaultMeta: { service: packageName },
  format,
  level: LOG_LEVEL,
  transports
})

// write morgan http request data as json to winston logs
logger.stream = {
  write: (json) => {
    const requestData = JSON.parse(json);
    const message = `${requestData.method} ${requestData.url} ${requestData.status}`
    logger.log('info', {
      ...requestData,
      message
    })
  }
}

// https://www.npmjs.com/package/morgan#tokens
morgan.token('id', req => req.id)
morgan.token('uid', req => req.user && req.user.id)
const tokenString = [
  'id',
  'http-version',
  'method',
  'remote-addr',
  'status',
  'total-time',
  'uid',
  'url',
  // 'response-time',
  // 'user-agent',
].map(token => `"${token}": ":${token}"`)
.join(', ');
const morganFormat = `{${tokenString}, "content-length": ":res[content-length]"}`

const requestLoggerMiddleware = morgan(morganFormat, { stream: logger.stream });

module.exports = {
  logger,
  requestLoggerMiddleware
}