create-react-app Server Side bootstrapping

// config/paths.js

module.exports = {
    ...
    appServer: resolveApp('server'),
    serverIndexJs: resolveApp('src/server.js'),
    ...
}
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As described on the github:

Webpack allows you to define externals - modules that should not be bundled.

When bundling with Webpack for the backend - you usually don't want to bundle its node_modules dependencies. This library creates an externals function that ignores node_modules when bundling in Webpack.

const path = require('path');
const paths = require('./paths');
const webpackNodeExternals = require('webpack-node-externals');

module.exports = {
    // Target Nodehs
    target: 'node',
    // Looking for the root of server app
    entry: paths.serverIndexJs,
    output: {
        // The build folder.
        path: paths.appServer,
        filename: 'server.js'
    },
    // Run Babel on every file
    module: {
        rules: [
            {
                test: /\.js?$/,
                loader: 'babel-loader',
                exclude: /node_modules/,
                options: {
                    presets: [
                        'react',
                        'stage-0',
                        ['env', { targets: { browsers: ['last 2 versions']}}]
                    ]
                }
            }
        ]
    },
    externals: [webpackNodeExternals()]
}
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