Production build configuration for a personal project using Vue+Vuetify and Webpack 4, with ExtractTextPlugin and SplitChunks.

build.js

console.log('build.js')
const rm = require('rimraf')
const path = require('path')
const chalk = require('chalk')
const webpack = require('webpack')
const config = require('./config')
const webpackConfig = require('./webpack.prod.conf')
const t0 = process.hrtime()

console.log(chalk.gray('---------------------PRODUCCIÓN----------------------'))

rm(path.join(config.build.assetsRoot, config.build.assetsSubDirectory), err => {
  if (err) throw err
  webpack(webpackConfig, function (err, stats) {
    if (err) throw err
    process.stdout.write(stats.toString({
      colors: true,
      modules: false,
      children: false,
      chunks: false,
      chunkModules: false
    }) + '\n')

    if (stats.hasErrors()) {
      console.log(chalk.red('  Error.'))
      process.exit(1)
    }
    const t1 = process.hrtime(t0)
    console.log(chalk.cyan('  Completado en ' + (t1[0]) + '.' + (t1[1]) + ' segundos.'))
    console.log(chalk.cyan('  A las: ' + new Date()))
  })
})

config.js

console.log('config.js')
// Based on template version: 1.1.3
// see http://vuejs-templates.github.io/webpack for documentation.

const path = require('path')

module.exports = {
  build: {
    env: { NODE_ENV: '"production"' },
    index: path.resolve(__dirname, '/build-app/index.html'),
    assetsRoot: path.resolve(__dirname, '/build-app/assets'),
    assetsSubDirectory: 'static',
    assetsPublicPath: '/',
    productionSourceMap: false,
    // Gzip off by default as many popular static hosts such as
    // Surge or Netlify already gzip all static assets for you.
    // Before setting to `true`, make sure to:
    // npm install --save-dev compression-webpack-plugin
    productionGzip: false,
    productionGzipExtensions: ['js', 'css'],
    // Run the build command with an extra argument to
    // View the bundle analyzer report after build finishes:
    // `npm run build --report`
    // Set to `true` or `false` to always turn it on or off
    //bundleAnalyzerReport: process.env.npm_config_report
    bundleAnalyzerReport: false
  },
  dev: {
    env: { NODE_ENV: '"development"' },
    port: process.env.PORT || 8080,
    autoOpenBrowser: true,
    assetsSubDirectory: 'static',
    assetsPublicPath: '/',
    proxyTable: {},
    // CSS Sourcemaps off by default because relative paths are "buggy"
    // with this option, according to the CSS-Loader README
    // (https://github.com/webpack/css-loader#sourcemaps)
    // In our experience, they generally work as expected,
    // just be aware of this issue when enabling this option.
    cssSourceMap: false
  }
}

package.json

{
  "scripts": {
    "build": "node build/build.js",
  },
  "dependencies": {
    "vue": "2.5.x",
  },
  "devDependencies": {
    "babel-core": "6.26.x",
    "babel-loader": "7.1.4",
    "babel-minify": "0.x.x",
    "babel-plugin-transform-runtime": "6.x.x",
    "babel-register": "6.x.x",
    "chalk": "2.3.2",
    "connect-history-api-fallback": "1.x.x",
    "copy-webpack-plugin": "4.x.x",
    "cross-env": "5.1.4",
    "cross-spawn": "5.x.x",
    "css-loader": "0.28.11",
    "eventsource-polyfill": "0.9.x",
    "extract-text-webpack-plugin": "^4.0.0-beta.0",
    "file-loader": "1.1.11",
    "friendly-errors-webpack-plugin": "1.6.x",
    "html-webpack-plugin": "3.1.0",
    "inject-loader": "3.0.x",
    "node-sass": "4.8.3",
    "opn": "5.3.0",
    "optimize-css-assets-webpack-plugin": "4.0.0",
    "portfinder": "1.0.x",
    "sass-loader": "6.0.7",
    "style-loader": "0.20.3",
    "url-loader": "1.0.1",
    "vue-loader": "14.2.2",
    "vue-style-loader": "4.1.0",
    "vue-template-compiler": "2.x.x",
    "webpack": "^4.2.0",
    "webpack-bundle-analyzer": "2.11.1",
    "webpack-dev-middleware": "3.0.1",
    "webpack-hot-middleware": "2.21.2",
    "webpack-merge": "4.1.2"
  },
  "engines": {
    "node": ">= 6.0.0",
    "npm": ">= 3.0.0"
  }
}

webpack.base.conf.js

console.log('webpack.base.conf.js')
const path = require('path')
const utils = require('./utils')
const config = require('./config')
const ExtractTextPlugin = require('extract-text-webpack-plugin')

function resolve(dir) {
  return path.join(__dirname, '..', dir)
}

module.exports = {
  entry: {
    app: "./src/main.js"
  },
  output: {
    path: config.build.assetsRoot,
    filename: "[name].js",
    publicPath: process.env.NODE_ENV === "production" ?
      config.build.assetsPublicPath :
      config.dev.assetsPublicPath
  },
  resolve: {
    extensions: [".js", ".vue", ".json"],
    symlinks: false,
    alias: {
      vue$: "vue/dist/vue.runtime.esm.js",
      "@": resolve("src")
    }
  },
  module: {
    rules: [{
        test: /\.vue$/,
        loader: "vue-loader",
        include: [resolve("src")],
        options: {
          loaders: ExtractTextPlugin.extract({
            use: [{
              loader: 'vue-style-loader',
              options: {
                minimize: true,
                processCssUrls: false,
                sourceMap: false,
              }
            },
            {
              loader: 'css-loader',
              options: {
                minimize: true,
                processCssUrls: false,
                sourceMap: false,
              }
            }],
            fallback: 'vue-style-loader'
          }),
          transformToRequire: {
            video: "src",
            source: "src",
            img: "src",
            image: "xlink:href"
          }
        }
      },
      {
        test: /\.js$/,
        loader: "babel-loader?cacheDirectory",
        include: [resolve("src"), resolve("test")]
      },
      {
        test: /\.(png|jpe?g|gif|svg)(\?.*)?$/,
        loader: "url-loader",
        options: {
          limit: 10000,
          name: utils.assetsPath("img/[name].[hash:7].[ext]")
        }
      },
      {
        test: /\.(mp4|webm|ogg|mp3|wav|flac|aac)(\?.*)?$/,
        loader: "url-loader",
        options: {
          limit: 10000,
          name: utils.assetsPath("media/[name].[hash:7].[ext]")
        }
      },
      {
        test: /\.(woff2?|eot|ttf|otf)(\?.*)?$/,
        loader: "url-loader",
        options: {
          limit: 10000,
          name: utils.assetsPath("fonts/[name].[hash:7].[ext]")
        }
      }
    ]
  }
};

webpack.prod.conf.js

console.log('webpack.prod.conf.js')
const path = require('path')
const utils = require('./utils')
const webpack = require('webpack')
const config = require('./config')
const merge = require('webpack-merge')
const baseWebpackConfig = require('./webpack.base.conf')
const CopyWebpackPlugin = require('copy-webpack-plugin')
const HtmlWebpackPlugin = require('html-webpack-plugin')
const ExtractTextPlugin = require('extract-text-webpack-plugin')
const OptimizeCSSPlugin = require('optimize-css-assets-webpack-plugin')

const env = process.env.NODE_ENV === 'testing'
? {
  NODE_ENV: 'testing'
}
: {
  NODE_ENV: 'production'
}

const webpackConfig = merge(baseWebpackConfig, {
  mode: process.env.NODE_ENV === 'testing' ? 'development' : 'production',
  module: {
    rules: utils.styleLoaders({
      sourceMap: config.build.productionSourceMap,
      extract: true
    })
  },
  devtool: config.build.productionSourceMap ? '#source-map' : false,
  output: {
    path: config.build.assetsRoot,
    filename: utils.assetsPath('js/[name].[chunkhash].js'),
    chunkFilename: utils.assetsPath('js/[id].[chunkhash].js')
  },
  plugins: [
    // http://vuejs.github.io/vue-loader/en/workflow/production.html
    new webpack.DefinePlugin({
      'process.env': env
    }),
    // ExtractTextPlugin extract css into its own file (must be version ^4.0.0-beta)
    new ExtractTextPlugin({
      filename: utils.assetsPath('css/[name].[contenthash].css')
    }),
    // Compress extracted CSS. We are using this plugin so that possible
    // duplicated CSS from different components can be deduped.
    new OptimizeCSSPlugin({
      cssProcessorOptions: {
        safe: true
      }
    }),
    // generate dist index.html with correct asset hash for caching.
    // you can customize output by editing /index.html
    // see https://github.com/ampedandwired/html-webpack-plugin
    new HtmlWebpackPlugin({
      filename:
        process.env.NODE_ENV === 'testing' ? 'index.html' : config.build.index,
      template: 'index.html',
      inject: true,
      minify: {
        removeComments: true,
        collapseWhitespace: true
        // more options:
        // https://github.com/kangax/html-minifier#options-quick-reference
      },
    }),
    new webpack.HashedModuleIdsPlugin(),
    new CopyWebpackPlugin([
      {
        from: path.resolve(__dirname, '../static'),
        to: config.build.assetsSubDirectory,
        ignore: ['.*']
      }
    ])
  ]
});

if (config.build.productionGzip) {
  const CompressionWebpackPlugin = require('compression-webpack-plugin')

  webpackConfig.plugins.push(
    new CompressionWebpackPlugin({
      asset: '[path].gz[query]',
      algorithm: 'gzip',
      test: new RegExp(
        '\\.(' +
        config.build.productionGzipExtensions.join('|') +
        ')$'
      ),
      threshold: 10240,
      minRatio: 0.8
    })
  )
}

if (config.build.bundleAnalyzerReport) {
  const BundleAnalyzerPlugin = require('webpack-bundle-analyzer').BundleAnalyzerPlugin
  webpackConfig.plugins.push(new BundleAnalyzerPlugin())
}

module.exports = webpackConfig

Webpack4+Vue with ExtractTextPlugin and SplitChunks project configuration

Don't forget to upgrade extract-text-webpack-plugin:
yarn upgrade extract-text-webpack-plugin@next --dev