text: 'use strict';
  
  const errorOverlayMiddleware = require('react-dev-utils/errorOverlayMiddleware');
  const evalSourceMapMiddleware = require('react-dev-utils/evalSourceMapMiddleware');
  const noopServiceWorkerMiddleware = require('react-dev-utils/noopServiceWorkerMiddleware');
  const ignoredFiles = require('react-dev-utils/ignoredFiles');
  const paths = require('./paths');
  const fs = require('fs');
  
  const protocol = process.env.HTTPS === 'true' ? 'https' : 'http';
  const host = process.env.HOST || '0.0.0.0';
  
  module.exports = function(proxy, allowedHost) {
    return {
      headers: { "Access-Control-Allow-Origin": "*" },
      // WebpackDevServer 2.4.3 introduced a security fix that prevents remote
      // websites from potentially accessing local content through DNS rebinding:
      // https://github.com/webpack/webpack-dev-server/issues/887
      // https://medium.com/webpack/webpack-dev-server-middleware-security-issues-1489d950874a
      // However, it made several existing use cases such as development in cloud
      // environment or subdomains in development significantly more complicated:
      // https://github.com/facebook/create-react-app/issues/2271
      // https://github.com/facebook/create-react-app/issues/2233
      // While we're investigating better solutions, for now we will take a
      // compromise. Since our WDS configuration only serves files in the `public`
      // folder we won't consider accessing them a vulnerability. However, if you
      // use the `proxy` feature, it gets more dangerous because it can expose
      // remote code execution vulnerabilities in backends like Django and Rails.
      // So we will disable the host check normally, but enable it if you have
      // specified the `proxy` setting. Finally, we let you override it if you
      // really know what you're doing with a special environment variable.
      disableHostCheck: !proxy || process.env.DANGEROUSLY_DISABLE_HOST_CHECK === 'true',
      // Enable gzip compression of generated files.
      compress: true,
      // Silence WebpackDevServer's own logs since they're generally not useful.
      // It will still show compile warnings and errors with this setting.
      clientLogLevel: 'none',
      // By default WebpackDevServer serves physical files from current directory
      // in addition to all the virtual build products that it serves from memory.
      // This is confusing because those files won’t automatically be available in
      // production build folder unless we copy them. However, copying the whole
      // project directory is dangerous because we may expose sensitive files.
      // Instead, we establish a convention that only files in `public` directory
      // get served. Our build script will copy `public` into the `build` folder.
      // In `index.html`, you can get URL of `public` folder with %PUBLIC_URL%:
      // <link rel="icon" href="%PUBLIC_URL%/favicon.ico">
      // In JavaScript code, you can access it with `process.env.PUBLIC_URL`.
      // Note that we only recommend to use `public` folder as an escape hatch
      // for files like `favicon.ico`, `manifest.json`, and libraries that are
      // for some reason broken when imported through Webpack. If you just want to
      // use an image, put it in `src` and `import` it from JavaScript instead.
      contentBase: paths.appPublic,
      // By default files from `contentBase` will not trigger a page reload.
      watchContentBase: true,
      // Enable hot reloading server. It will provide /sockjs-node/ endpoint
      // for the WebpackDevServer client so it can learn when the files were
      // updated. The WebpackDevServer client is included as an entry point
      // in the Webpack development configuration. Note that only changes
      // to CSS are currently hot reloaded. JS changes will refresh the browser.
      hot: true,
      // Use 'ws' instead of 'sockjs-node' on server since we're using native
      // websockets in `webpackHotDevClient`.
      transportMode: 'ws',
      // Prevent a WS client from getting injected as we're already including
      // `webpackHotDevClient`.
      injectClient: false,
      // It is important to tell WebpackDevServer to use the same "root" path
      // as we specified in the config. In development, we always serve from /.
      publicPath: '/',
      // WebpackDevServer is noisy by default so we emit custom message instead
      // by listening to the compiler events with `compiler.hooks[...].tap` calls above.
      quiet: true,
      // Reportedly, this avoids CPU overload on some systems.
      // https://github.com/facebook/create-react-app/issues/293
      // src/node_modules is not ignored to support absolute imports
      // https://github.com/facebook/create-react-app/issues/1065
      watchOptions: {
        ignored: ignoredFiles(paths.appSrc),
      },
      // Enable HTTPS if the HTTPS environment variable is set to 'true'
      https: protocol === 'https',
      host,
      overlay: false,
      historyApiFallback: {
        // Paths with dots should still use the history fallback.
        // See https://github.com/facebook/create-react-app/issues/387.
        disableDotRule: true,
      },
      public: allowedHost,
      proxy,
      before(app, server) {
        if (fs.existsSync(paths.proxySetup)) {
          // This registers user provided middleware for proxy reasons
          require(paths.proxySetup)(app);
        }
  
        // This lets us fetch source contents from webpack for the error overlay
        app.use(evalSourceMapMiddleware(server));
        // This lets us open files from the runtime error overlay.
        app.use(errorOverlayMiddleware());
  
        // This service worker file is effectively a 'no-op' that will reset any
        // previous service worker registered for the same host:port combination.
        // We do this in development to avoid hitting the production cache if
        // it used the same host and port.
        // https://github.com/facebook/create-react-app/issues/2272#issuecomment-302832432
        app.use(noopServiceWorkerMiddleware());
      },
    };
  };
  