webpack.config.js

const path = require("path");
const AwsSamPlugin = require("aws-sam-webpack-plugin");

const awsSamPlugin = new AwsSamPlugin();

module.exports = {
  // Loads the entry object from the AWS::Serverless::Function resources in your
  // SAM config. Setting this to a function will
  entry: () => awsSamPlugin.entry(),

  // Write the output to the .aws-sam/build folder
  output: {
    filename: (chunkData) => awsSamPlugin.filename(chunkData),
    libraryTarget: "commonjs2",
    path: path.resolve(".")
  },

  // Create source maps
  devtool: "source-map",

  // Resolve .ts and .js extensions
  resolve: {
    extensions: [".ts", ".js"]
  },

  // Target node
  target: "node",

  // AWS recommends always including the aws-sdk in your Lambda package but excluding can significantly reduce
  // the size of your deployment package. If you want to always include it then comment out this line. It has
  // been included conditionally because the node10.x docker image used by SAM local doesn't include it.
  externals: process.env.NODE_ENV === "development" ? [] : ["aws-sdk"],

  // Set the webpack mode
  mode: process.env.NODE_ENV || "production",

  // Add the AWS SAM Webpack plugin
  plugins: [awsSamPlugin]
};