Firebase Google Cloud Functions REST router

index.js

require('dotenv').config({ path: __dirname + '/.env' })

const fs = require('fs')
const api = require('./middleware/router')
const functions = require('firebase-functions')

// runtime options
const runtimeOpts = {
  memory: '256MB',
  timeoutSeconds: 500
}

// exports
fs.readdirSync(__dirname + '/api/').forEach(functionName => {
  exports[functionName.slice(0, -3)] = functions.runWith(runtimeOpts).https.onRequest(api)
})

resource.js

const get = (req, res) => {
  res.status(200).send('fetch site: ' + req.body.id)
}

const all = (req, res) => {
  res.status(200).send('fetch sites: ' + req.body.id)
}

const post = (req, res) => {
  res.status(200).send('create new site: ' + req.body.id)
}

const put = (req, res) => {
  res.status(200).send('update site: ' + req.body.id)
}

// exports
module.exports = {
  all,
  get,
  put,
  post
}

router.js

require('colors')

const path = require('path')
const express = require('express')
const cookies = require('cookie-parser')()
const corsHdr = require('cors')({ origin: true })
// const appAuth = require('./authGuard')
const api = express()

api.use(corsHdr)
api.use(cookies)
// api.use(appAuth)

api.all('*', (req, res, next) => {
  const functionType = req.method.toLocaleLowerCase()
  const functionFile = '../api/' + process.env.FUNCTION_NAME

  try {
    if (functionType === 'get' && path.basename(req.path).slice(-1) === 's') {
      console.log(
        functionType.toUpperCase().red,
        'request:'.yellow,
        ('/' + path.basename(functionFile) + 's').red,
        'body:'.yellow,
        req.body
      )

      return require(functionFile).all(req, res, next)
    } else if (functionType === 'get') req.body.id = path.basename(req.path)

    console.log(
      functionType.toUpperCase().red,
      'request:'.yellow,
      ('/' + path.basename(functionFile)).red,
      'body:'.yellow,
      req.body
    )

    return require(functionFile)[functionType](req, res, next)
  } catch (error) {
    console.error(error)

    res.status(400).send('Bad req')
  }
})

// exports
module.exports = api

What: when creating firebase backend functions with express, the typical use case is to route all API requests to a single cloud function performing routing.

Problem: the issue with the solution above is that Firebase Functions log reports the same function name for all cloud function requests.

Solution: dynamically rendered Google Cloud Functions by scanning javascript files located in /functions/api folder. Each javascript will create a unique HTTP cloud function export route and execute function name based on the request method: GET, POST, PUT etc.

To Do dynamically render firebase.json hosting rewrite rules based on available functions.