index.js

#!/usr/bin/env node

'use strict'

const express = require('express')
const bodyParser = require('body-parser')
const os = require('os')
const mjml2html = require('mjml')
const program = require('commander')
const beautifyHtml = require('js-beautify').html
const minifyHtml = require('html-minifier').minify

program.usage('[options]').parse(process.argv)

const app = express()

app.use(
  bodyParser.text({
    inflate: true,
    limit: '2048kb',
    type: '*/*'
  })
)

const opts = {
  keepComments: process.env.MJML_KEEP_COMMENTS === 'true',
  validationLevel: ['soft', 'strict', 'skip']
    .includes(process.env.MJML_VALIDATION_LEVEL)
    ? process.env.MJML_VALIDATION_LEVEL
    : 'soft',
  healthchecks: process.env.HEALTHCHECK === 'true'
}

const charsetOpts = {
  write: process.env.CHARSET,
  contentType: process.env.DEFAULT_RESPONSE_CONTENT_TYPE || 'text/html; charset=utf-8'
}

const doBeautify = process.env.MJML_BEAUTIFY === 'true'
const doMinifiy = process.env.MJML_MINIFY === 'true'

app.all('*', function (req, res) {
  // enable cors
  if (process.env.CORS) {
    res.header('Access-Control-Allow-Origin', process.env.CORS)
    res.header('Access-Control-Allow-Headers', '*')
    res.header('Access-Control-Allow-Methods', 'POST')
    res.header('Access-Control-Max-Age', '-1')
  }

  // ensure content type is set
  if (!req.headers['content-type']) {
    res.status(500).send('Content-Type must be set, use text/plain if unsure')
    return
  }

  try {
    const result = mjml2html(req.body || '', opts)

    if (doBeautify) {
      result.html = beautifyHtml(result.html, {
        indent_size: 2,
        wrap_attributes_indent_size: 2,
        max_preserve_newline: 0,
        preserve_newlines: false,
        end_with_newline: true
      })
    }

    if (doMinifiy) {
      result.html = minifyHtml(result.html, {
        collapseWhitespace: true,
        minifyCSS: false,
        caseSensitive: true,
        removeEmptyAttributes: true
      })
    }

    if (charsetOpts.contentType !== '') {
      res.writeHead(200, { 'Content-Type': charsetOpts.contentType })
    } else {
      // fall back
      res.writeHead(200, { 'Content-Type': 'text/html' })
    }

    if (charsetOpts.write !== '') {
      res.write(result.html, charsetOpts.write)
    } else {
      res.write(result.html)
    }

    res.end()
  } catch (ex) {
    // print error details
    console.log(req.body || '')
    console.error(ex)
    console.log('')

    res.writeHead(400, { 'Content-Type': 'text/plain' })
    res.end(ex.message)
  }
})

const server = app.listen(process.env.PORT || 80)

const signals = {
  SIGHUP: 1,
  SIGINT: 2,
  SIGTERM: 15
}

const shutdown = (signal, value) => {
  server.close(() => {
    console.log(`app stopped by ${signal} with value ${value}`)
    process.exit(128 + value)
  })
}

Object.keys(signals).forEach((signal) => {
  process.on(signal, () => {
    console.log(`process received a ${signal} signal`)
    shutdown(signal, signals[signal])
  })
})

console.log('self: ' + os.hostname() + ':' + server.address().port)
console.log('cors: ' + (process.env.CORS || 'n/a'))
console.log('healthchecks: ' + opts.healthchecks)
console.log('mjml keep comments: ' + opts.keepComments)
console.log('mjml validation level: ' + opts.validationLevel)
console.log('mjml beautify: ' + doBeautify)
console.log('mjml minify: ' + doMinifiy)
console.log('node default content-type:' + charsetOpts.contentType)
console.log('node write charset:' + charsetOpts.write)
console.log('')
console.log('POST mjml as text/plain raw body, result will be returned as text/html.')