Individual webpack stats per entrypoint

webpack.config.ts

const path = require('path')
const slsw = require('serverless-webpack')
const { StatsWriterPlugin } = require('webpack-stats-plugin')
const yaml = require('js-yaml')
const fs = require('fs')

require('events').EventEmitter.defaultMaxListeners = 20 // default: 10, using 11 at the moment

/**
 * slsw.lib.entries is used when invoking webpack from serverless, e.g. `serverless package`
 * But it's not defined when invoking webpack independently, so we provide a fallback
 */
const entry =
    slsw.lib.entries && Object.keys(slsw.lib.entries).length > 0
        ? slsw.lib.entries
        : Object.assign(
              ...Object.values(yaml.load(fs.readFileSync(path.resolve(__dirname, 'serverless.yml'))).functions).map(
                  (f) => ({
                      [f.handler.split('.')[0]]: `./${f.handler.split('.')[0]}.ts`,
                  })
              )
          )

const isDev = slsw.lib.isLocal || process.env.LOCAL || process.env.NODE_ENV === 'development' // etc.

/**
 * When packaging individually, serverless-webpack forms individual webpack configurations by
 * deeply cloning this one, and adjusting the entrypoints. That means we can tell which function
 * we are compiling, and vary the filename accurately.
 *
 * The returned path must be relative (to the output dir), not absolute.
 */
const statsFilename = (c) => `../stats/stats-${path.basename(c.entrypoints.entries().next().value[0])}.json`

module.exports = {
    context: process.cwd(),
    mode: isDev ? 'development' : 'production',
    devtool: isDev ? 'inline-source-map' : 'none',
    entry,
    externals: ['aws-sdk', 'pino-pretty', 'pino-debug', 'debug', 'pg'],
    resolve: {
        extensions: ['.ts', '.js'],
    },
    output: {
        libraryTarget: 'commonjs2',
        path: path.join(__dirname, '.webpack'),
        filename: '[name].js',
    },
    target: 'node',
    module: {
        rules: [
            {
                // Include ts, tsx files.
                test: /\.tsx?$/,
                include: path.resolve(__dirname, 'src'),
                use: [
                    {
                        loader: 'ts-loader',
                        options: {
                            transpileOnly: true, // typechecking is through tsc --noEmit
                            experimentalWatchApi: true,
                        },
                    },
                ],
            },
        ],
    },
    plugins: [].concat(
        process.env.WEBPACK_STATS
            ? [
                  new StatsWriterPlugin({
                      filename: statsFilename,
                      fields: null,
                      stats: {
                          maxModules: Infinity,
                          source: false,
                      },
                  }),
              ]
            : []
    ),
}