webpackDevServer.config.js

"use strict";

const errorOverlayMiddleware = require("react-dev-utils/errorOverlayMiddleware");
const evalSourceMapMiddleware = require("react-dev-utils/evalSourceMapMiddleware");
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, port) {
  return {
    // 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.
    allowedHosts:
      !proxy || process.env.DANGEROUSLY_DISABLE_HOST_CHECK === "true"
        ? "all"
        : "auto",
    // Enable gzip compression of generated files.
    compress: 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
    static: {
      // 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.
      directory: paths.appPublic,
      // 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: "/",
      watch: {
        ignored: ignoredFiles(paths.appSrc),
      },
    },
    // Enable HTTPS if the HTTPS environment variable is set to 'true'
    server: {
      type: protocol,
    },
    host,
    port,
    historyApiFallback: {
      // Paths with dots should still use the history fallback.
      // See https://github.com/facebook/create-react-app/issues/387.
      disableDotRule: true,
    },
    client: {
      // Silence WebpackDevServer's own logs since they're generally not useful.
      // It will still show compile warnings and errors with this setting.
      logging: "none",
      webSocketURL: allowedHost,
      overlay: false,
    },
    proxy,
    setupMiddlewares: (middlewares, server) => {
      if (fs.existsSync(paths.proxySetup)) {
        // This registers user provided middleware for proxy reasons
        require(paths.proxySetup)(server.app);
      }

      middlewares.unshift(
        // This lets us fetch source contents from webpack for the error overlay.
        evalSourceMapMiddleware(server),
        // This lets us open files from the runtime error overlay.
        errorOverlayMiddleware()
      );
      return middlewares;
    },
  };
};