webpack devServer.proxy 官方文檔
devServer.proxy 簡單使用說明

object [object, function]

Proxying some URLs can be useful when you have a separate API backend development server and you want to send API requests on the same domain.

The dev-server makes use of the powerful http-proxy-middleware package. Check out its documentationfor more advanced usages. Note that some of http-proxy-middleware's features do not require a target key, e.g. its router feature, but you will still need to include a target key in your configuration here, otherwise webpack-dev-server won't pass it along to http-proxy-middleware.

With a backend on localhost:3000, you can use this to enable proxying:

webpack.config.js

module.exports = {
  //...
  devServer: {
    proxy: {
      '/api': 'http://localhost:3000',
    },
  },
};

A request to /api/users will now proxy the request to http://localhost:3000/api/users.

If you don't want /api to be passed along, we need to rewrite the path:

webpack.config.js

module.exports = {
  //...
  devServer: {
    proxy: {
      '/api': {
        target: 'http://localhost:3000',
        pathRewrite: { '^/api': '' },
      },
    },
  },
};

A backend server running on HTTPS with an invalid certificate will not be accepted by default. If you want to, modify your configuration like this:

webpack.config.js

module.exports = {
  //...
  devServer: {
    proxy: {
      '/api': {
        target: 'https://other-server.example.com',
        secure: false,
      },
    },
  },
};

Sometimes you don't want to proxy everything. It is possible to bypass the proxy based on the return value of a function.

In the function, you get access to the request, response, and proxy options.

• Return null or undefined to continue processing the request with proxy.
• Return false to produce a 404 error for the request.
• Return a path to serve from, instead of continuing to proxy the request.

E.g. for a browser request, you want to serve an HTML page, but for an API request, you want to proxy it. You could do something like this:

webpack.config.js

module.exports = {
  //...
  devServer: {
    proxy: {
      '/api': {
        target: 'http://localhost:3000',
        bypass: function (req, res, proxyOptions) {
          if (req.headers.accept.indexOf('html') !== -1) {
            console.log('Skipping proxy for browser request.');
            return '/index.html';
          }
        },
      },
    },
  },
};

If you want to proxy multiple, specific paths to the same target, you can use an array of one or more objects with a context property:

webpack.config.js

module.exports = {
  //...
  devServer: {
    proxy: [
      {
        context: ['/auth', '/api'],
        target: 'http://localhost:3000',
      },
    ],
  },
};

Note that requests to root won't be proxied by default. To enable root proxying, the devMiddleware.index option should be specified as a falsy value:

webpack.config.js

module.exports = {
  //...
  devServer: {
    devMiddleware: {
      index: false, // specify to enable root proxying
    },
    proxy: {
      context: () => true,
      target: 'http://localhost:1234',
    },
  },
};

The origin of the host header is kept when proxying by default, you can set changeOrigin to true to override this behaviour. It is useful in some cases like using name-based virtual hosted sites.

webpack.config.js

module.exports = {
  //...
  devServer: {
    proxy: {
      '/api': {
        target: 'http://localhost:3000',
        changeOrigin: true,
      },
    },
  },
};