Provide migration guide for setupMiddlewares

[oobles]

Documentation Is:

• [x ] Missing
• [x ] Needed
• Confusing
• Not Sure?

Please Explain in Detail...

The recent change for issue #4068 deprecates onAfterSetupMiddleware and onBeforeSetupMiddleware. The commit making the change provides a new example, but there's no migration guide on how to migrate away from the deprecated configuration options.

Your Proposal for Changes

[snitin315]

Before

module.exports = {
  //...
  devServer: {
    onAfterSetupMiddleware: function (devServer) {
      if (!devServer) {
        throw new Error('webpack-dev-server is not defined');
      }

      devServer.app.get('/some/after/path', function (req, res) {
        res.json({ custom: 'response-after' });
      });
    },

    onBeforeSetupMiddleware: function (devServer) {
      if (!devServer) {
        throw new Error('webpack-dev-server is not defined');
      }

      devServer.app.get('/some/before/path', function (req, res) {
        res.json({ custom: 'response-before' });
      });
    },
  },
};

After

module.exports = {
  // ...
  devServer: {
    setupMiddlewares: (middlewares, devServer) => {
      if (!devServer) {
        throw new Error('webpack-dev-server is not defined');
      }

       // onBeforeSetupMiddleware
      devServer.app.get('/some/before/path', (_, response) => {
         response.json({ custom: 'response-before' });
      });

      // onAfterSetupMiddleware
      middlewares.push({
        name: 'after-middleware',
        // `path` is optional
        path: '/some/after/path',
        middleware: (req, res) => {
          res.json({ custom: 'response-after' });
        },
      });

      // another after middleware
      middlewares.push((req, res) => {
        res.send('Hello World!');
      });

      return middlewares;
    },
  },
};

I believe this should be the migration. /cc @alexander-akait

[markcipolla]

Thanks @snitin315 🙏🏻

How would you migrate a before and after block with server.use instead of server.get?
e.g. the below:

before(app, server) {
      // Keep `evalSourceMapMiddleware` and `errorOverlayMiddleware`
      // middlewares before `redirectServedPath` otherwise will not have any effect
      // 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());

      if (fs.existsSync(paths.proxySetup)) {
        // This registers user provided middleware for proxy reasons
        require(paths.proxySetup)(app);
      }
    },
    after(app) {
      // Redirect to `PUBLIC_URL` or `homepage` from `package.json` if url not match
      app.use(redirectServedPath(paths.publicUrlOrPath));

      // 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(paths.publicUrlOrPath));
    },

[alexander-akait]

middlewares is just array, put it before or after, as you work with arrays and return modified array

[otakustay]

Note that app.get(...) in onAfterSetupMiddleware is not the same as app.get(...) in setupMiddlewares.

It seems app.get() in setupMiddlewares are always applied before middlewares are applied, if we have a config like this:

{
    onAfterSetupMiddleware: server => {
        server.app.get('/__index__.html', (req, res) => res.send('foo'));
    },
    config.historyApiFallback = {
        index: '/__index__.html',
        disableDotRule: true,
    };
}

The route /__index__.html will take place for history api fallback, however if we changed it to this:

{
    setupMiddlewares: (middlewares, server) => {
        server.app.get('/__index__.html', (req, res) => res.send('foo'));
        return middlewares;
    },
    config.historyApiFallback = {
        index: '/__index__.html',
        disableDotRule: true,
    };
}

History api fallback are broken, we have to transform it into a middleware like:

middlewares.unshift({
    path: '/__index__.html',
    handler: (req, res, next) => {
        if (req.method === 'GET') {
            res.send('foo');
        }
        else {
            next();
        }
    }
});

In this way we have to add a request.method check in middleware implementation.

[alexander-akait]

Yes, it is good solution 👍

[coderXaj]

(node:9304) [DEP_WEBPACK_DEV_SERVER_ON_AFTER_SETUP_MIDDLEWARE] DeprecationWarning: 'onAfterSetupMiddleware' option is deprecated. Please use the 'setupMiddlewares' option.
(Use node --trace-deprecation ... to show where the warning was created)
(node:9304) [DEP_WEBPACK_DEV_SERVER_ON_BEFORE_SETUP_MIDDLEWARE] DeprecationWarning: 'onBeforeSetupMiddleware' option is deprecated. Please use the 'setupMiddlewares' option.

Can any one please tell me how solve to this error my localhost is not opening after i get this error.

[umair39]

Before

module.exports = {
  //...
  devServer: {
    onAfterSetupMiddleware: function (devServer) {
      if (!devServer) {
        throw new Error('webpack-dev-server is not defined');
      }

      devServer.app.get('/some/after/path', function (req, res) {
        res.json({ custom: 'response-after' });
      });
    },

    onBeforeSetupMiddleware: function (devServer) {
      if (!devServer) {
        throw new Error('webpack-dev-server is not defined');
      }

      devServer.app.get('/some/before/path', function (req, res) {
        res.json({ custom: 'response-before' });
      });
    },
  },
};

After

module.exports = {
  // ...
  devServer: {
    setupMiddlewares: (middlewares, devServer) => {
      if (!devServer) {
        throw new Error('webpack-dev-server is not defined');
      }

       // onBeforeSetupMiddleware
      devServer.app.get('/some/before/path', (_, response) => {
         response.json({ custom: 'response-before' });
      });

      // onAfterSetupMiddleware
      middlewares.push({
        name: 'after-middleware',
        // `path` is optional
        path: '/some/after/path',
        middleware: (req, res) => {
          res.json({ custom: 'response-after' });
        },
      });

      // another after middleware
      middlewares.push((req, res) => {
        res.send('Hello World!');
      });

      return middlewares;
    },
  },
};

I believe this should be the migration. /cc @alexander-akait

i am facing same issue how i use that code in node module files

[umair39]

where i can find file to isert modified code

[alexander-akait]

webpack.config.js file

[darkcohiba]

@snitin315 I can not find where to replace the code with the updated segment, what is the module this goes in?