gurubot2/app/index.js

const express = require('express');
const webpack = require('webpack');
const path = require('path');

const webpackConfig = require('../webpack.config');

const __DEV__ = process.env.NODE_ENV === 'development';

function healthEndpoint(app) {
    app.get('/health', (req, res) => {
        res.send('OK');
    });

    return app;
}

function setupDevServer(app) {
    if (!__DEV__) {
        return app;
    }

    const compiler = webpack(webpackConfig);

    const serverOptions = {
        quiet: true,
        publicPath: webpackConfig.output.publicPath,
        hot: true
    };

    // eslint-disable-next-line global-require
    app.use(require('webpack-dev-middleware')(compiler, serverOptions));

    // eslint-disable-next-line global-require
    app.use(require('webpack-hot-middleware')(compiler));

    return app;
}

function clientRoute(app) {
    app.use(express.static(path.resolve(__dirname, '../static')));

    return app;
}

function run() {
    const app = express();

    healthEndpoint(app);
    setupDevServer(app);
    clientRoute(app);

    const port = process.env.PORT || 3000;

    app.listen(port, () => {
        console.log('Listening on port', port);
    });
}

module.exports = {
    run
};