Bundle files that aren’t required or imported:

const ExtractSass = {
  entry: glob_entries('./public/styles/external/*.less'),
  output: {
    filename: './.build/junk/[name].[chunkhash].js',
  },
  module: {
    loaders: [{
      test: /\.less$/,
      loader: ExtractTextPlugin.extract(
        'isomorphic-style-loader',
        'css-loader?modules&localIdentName=[name]_[local]',
        'less-loader'
      )
    }]
  },
  plugins: [
    new ExtractTextPlugin('./.build/css/[name].css')
  ]
};

Dependencies

• extract-text-webpack-plugin
• webpack-glob-entries
• isomorphic-style-loader

The trick: create JS files for each LESS file, then extract them to CSS.