webpack.config.js

const path = require("path")
const slsw = require("serverless-webpack")
const nodeExt = require("webpack-node-externals")

const stage = slsw.lib.serverless
  ? slsw.lib.serverless.processedInput.options.stage
  : "dev"

function srcPath(subdir) {
  return path.join(__dirname, "src", subdir)
}

function useIstanbulInstrumenterLoader() {
  if (stage === "dev" || stage === "test") {
    return [{
      test: /\.(js)$/,
      use: {
        loader: "istanbul-instrumenter-loader",
        options: { esModules: true }
      },
      enforce: "post",
      exclude: /node_modules|\.test\.js$/,
    }]
  }

  return []
}

module.exports = {
  mode: stage === "dev" ? "development" : "production",
  stats: stage === "dev" ? "verbose" : "errors-only",
  entry: slsw.lib.entries,
  devtool: "source-map",
  resolve: {
    extensions: [
      ".js",
      ".json"
    ],
    alias: {
      "@components": srcPath("components"),
      "@errors": srcPath("errors"),
      "@utils": srcPath("utils"),
      "@middlewares": srcPath("middlewares"),
      "@models": srcPath("models"),
      "@requests": srcPath("requests"),
      "@responses": srcPath("responses"),
      "@transformers": srcPath("transformers"),
      "@workers": srcPath("workers"),
      "@validations": srcPath("validations")
    }
  },
  output: {
    libraryTarget: "commonjs",
    path: path.join(__dirname, ".webpack"),
    filename: "[name].js",
  },
  target: "node",
  module: {
    rules: [
      ...useIstanbulInstrumenterLoader(),
      { test: /\.js$/, loader: "babel-loader", exclude: /(node_modules)/ }
    ]
  },
  plugins: [],
  optimization: {
    removeAvailableModules: true,
    occurrenceOrder: true
  },
  externals: [ nodeExt() ]
}