using serverless upload file to s3

serverless-s3-upload.js

'use strict'

const AWS = require('aws-sdk')
const Busboy = require('busboy')
const S3 = new AWS.S3()

const makeResponse = (error, result) => {
  const statusCode = error && error.statusCode || 200
  return {
    statusCode,
    headers: {
      "Access-Control-Allow-Origin" : "*"
    },
    body: JSON.stringify(result),
  }
}

const upload = (path, file, contentType, callback) => {
  const params = {
    Bucket: 'activity',
    Key: path,
    Body: file,
    ACL: 'public-read',
    ContentType: contentType
  }
  S3.upload(params, (err, res) => {
    if (err) console.error(err, res)
    callback(err, res)
  })
}



module.exports.upload = (req, context, callback) => {
  const { headers } = req
  const busboy = new Busboy({ headers })
  const uploadData = {
    file: null,
    path: null,
    mimetype: null
  }
  

  let formData = {}
  busboy.on('field', function(fieldname, value) {
    formData[fieldname] = value
  })

  busboy.on('file', (fieldname, file, filename, encoding, mimetype) => {
    file.on('data', function(data) {
      uploadData.file = data
      uploadData.contentType = mimetype
    })
  })

  busboy.on('error', () => {
    console.error(error)
  })

  busboy.on('finish', function() {
    uploadData.path = formData.path

    const { path, file, contentType } = uploadData
    upload(path, file, contentType, (error, result) => {
      if(error) context

      const response = makeResponse(error, result)
      context.succeed(response)
    })
  })

  busboy.write(req.body, 'binary')
  busboy.end()  
}