pretty-json-log.js

#!/usr/bin/env node
const readline = require('readline')
const colors = require('colors/safe')

const rl = readline.createInterface({
  input: process.stdin,
  output: process.stdout,
  terminal: false
})

const logMap = {
  60: {
    name: 'Fatal',
    colors: ['bgRed']
  },
  50: {
    name: 'Error',
    colors: ['bgRed']
  },
  40: {
    name: 'Warn',
    colors: ['bgYellow', 'black']
  },
  30: {
    name: 'Info',
    colors: ['bgBlue']
  },
  20: {
    name: 'Debug',
    colors: ['bgGray']
  },
  10: {
    name: 'Trace',
    colors: ['bgGray']
  }
}

rl.on('line', function (line) {
  try {
    const parsed = JSON.parse(line)
    const levelMapped = logMap[parsed.level]

    let str = `${levelMapped.name}[${parsed.context || 'Top'}]`
    let prefix = levelMapped.colors.reduce((str, color) => colors[color](str), str)

    console.log(`${prefix} ${parsed.msg}`)
  } catch (err) {
    console.log(line)
  }
})