1  'use strict';
 2  
 3  const errorOverlayMiddleware = require('react-dev-utils/errorOverlayMiddleware');
 4  const noopServiceWorkerMiddleware = require('react-dev-utils/noopServiceWorkerMiddleware');
 5  const ignoredFiles = require('react-dev-utils/ignoredFiles');
 6  const config = require('./webpack.config.dev');
 7  const paths = require('./paths');
 8  
 9  const protocol = process.env.HTTPS === 'true' ? 'https' : 'http';
10  const host = process.env.HOST || '0.0.0.0';
11  
12  module.exports = function(proxy, allowedHost) {
13    return {
14      // WebpackDevServer 2.4.3 introduced a security fix that prevents remote
15      // websites from potentially accessing local content through DNS rebinding:
16      // https://github.com/webpack/webpack-dev-server/issues/887
17      // https://medium.com/webpack/webpack-dev-server-middleware-security-issues-1489d950874a
18      // However, it made several existing use cases such as development in cloud
19      // environment or subdomains in development significantly more complicated:
20      // https://github.com/facebookincubator/create-react-app/issues/2271
21      // https://github.com/facebookincubator/create-react-app/issues/2233
22      // While we're investigating better solutions, for now we will take a
23      // compromise. Since our WDS configuration only serves files in the `public`
24      // folder we won't consider accessing them a vulnerability. However, if you
25      // use the `proxy` feature, it gets more dangerous because it can expose
26      // remote code execution vulnerabilities in backends like Django and Rails.
27      // So we will disable the host check normally, but enable it if you have
28      // specified the `proxy` setting. Finally, we let you override it if you
29      // really know what you're doing with a special environment variable.
30      disableHostCheck:
31        !proxy || process.env.DANGEROUSLY_DISABLE_HOST_CHECK === 'true',
32      // Enable gzip compression of generated files.
33      compress: true,
34      // Silence WebpackDevServer's own logs since they're generally not useful.
35      // It will still show compile warnings and errors with this setting.
36      clientLogLevel: 'none',
37      // By default WebpackDevServer serves physical files from current directory
38      // in addition to all the virtual build products that it serves from memory.
39      // This is confusing because those files won’t automatically be available in
40      // production build folder unless we copy them. However, copying the whole
41      // project directory is dangerous because we may expose sensitive files.
42      // Instead, we establish a convention that only files in `public` directory
43      // get served. Our build script will copy `public` into the `build` folder.
44      // In `index.html`, you can get URL of `public` folder with %PUBLIC_URL%:
45      // <link rel="shortcut icon" href="%PUBLIC_URL%/favicon.ico">
46      // In JavaScript code, you can access it with `process.env.PUBLIC_URL`.
47      // Note that we only recommend to use `public` folder as an escape hatch
48      // for files like `favicon.ico`, `manifest.json`, and libraries that are
49      // for some reason broken when imported through Webpack. If you just want to
50      // use an image, put it in `src` and `import` it from JavaScript instead.
51      contentBase: paths.appPublic,
52      // By default files from `contentBase` will not trigger a page reload.
53      watchContentBase: true,
54      // Enable hot reloading server. It will provide /sockjs-node/ endpoint
55      // for the WebpackDevServer client so it can learn when the files were
56      // updated. The WebpackDevServer client is included as an entry point
57      // in the Webpack development configuration. Note that only changes
58      // to CSS are currently hot reloaded. JS changes will refresh the browser.
59      hot: true,
60      // It is important to tell WebpackDevServer to use the same "root" path
61      // as we specified in the config. In development, we always serve from /.
62      publicPath: config.output.publicPath,
63      // WebpackDevServer is noisy by default so we emit custom message instead
64      // by listening to the compiler events with `compiler.plugin` calls above.
65      quiet: true,
66      // Reportedly, this avoids CPU overload on some systems.
67      // https://github.com/facebookincubator/create-react-app/issues/293
68      // src/node_modules is not ignored to support absolute imports
69      // https://github.com/facebookincubator/create-react-app/issues/1065
70      watchOptions: {
71        ignored: ignoredFiles(paths.appSrc),
72      },
73      // Enable HTTPS if the HTTPS environment variable is set to 'true'
74      https: protocol === 'https',
75      host: host,
76      overlay: false,
77      historyApiFallback: {
78        // Paths with dots should still use the history fallback.
79        // See https://github.com/facebookincubator/create-react-app/issues/387.
80        disableDotRule: true,
81      },
82      public: allowedHost,
83      proxy,
84      before(app) {
85        // This lets us open files from the runtime error overlay.
86        app.use(errorOverlayMiddleware());
87        // This service worker file is effectively a 'no-op' that will reset any
88        // previous service worker registered for the same host:port combination.
89        // We do this in development to avoid hitting the production cache if
90        // it used the same host and port.
91        // https://github.com/facebookincubator/create-react-app/issues/2272#issuecomment-302832432
92        app.use(noopServiceWorkerMiddleware());
93      },
94    };
95  };