webpack.config.js

const path = require('path')
const decompress = require('decompress')

const SHARP_VERSION = '0.18.2'
const sharpTarball = path.join(
  __dirname,
  `lambda-sharp/tarballs/sharp-${SHARP_VERSION}-aws-lambda-linux-x64-node-6.10.1.tar.gz`
)
const webpackDir = path.join(__dirname, '.webpack/')

function ExtractTarballPlugin (archive, to) {
  return {
    apply: (compiler) => {
      compiler.plugin('emit', (compilation, callback) => {
        decompress(path.resolve(archive), path.resolve(to))
          .then(() => callback())
          .catch(error => console.error('Unable to extract archive ', archive, to, error.stack))
      })
    },
  }
}

module.exports = {
  entry: './src/handler',
  target: 'node',
  module: {
    rules: [
      {
        test: /\.js$/,
        loader: 'babel-loader',
        include: __dirname,
        exclude: /node_modules/,
        options: {
          presets: ['env'],
        },
      },
    ],
  },
  output: {
    libraryTarget: 'commonjs',
    path: path.resolve(__dirname, '.webpack'),
    filename: 'handler.js', // this should match the first part of function handler in serverless.yml
  },
  externals: ['sharp', 'aws-sdk'],
  plugins: [new ExtractTarballPlugin(sharpTarball, webpackDir)],
}