Add hooks for overrides

.gitignore

@@ -7,3 +7,4 @@ template/src/__tests__/__snapshots__/
 lerna-debug.log
 npm-debug.log
 /.changelog
+.idea

packages/react-scripts/config/webpack.config.dev.js

@@ -36,7 +36,7 @@ var env = getClientEnvironment(publicUrl);
 // This is the development configuration.
 // It is focused on developer experience and fast rebuilds.
 // The production configuration is different and lives in a separate file.
-module.exports = {
+module.exports = require('./webpack.config.dev.override')({
   // You may want 'eval' instead if you prefer to see the compiled output in DevTools.
   // See the discussion in https://github.com/facebookincubator/create-react-app/issues/343.
   devtool: 'cheap-module-source-map',
@@ -235,4 +235,4 @@ module.exports = {
     net: 'empty',
     tls: 'empty'
   }
-};
+});

packages/react-scripts/config/webpack.config.dev.override.js

@@ -0,0 +1,5 @@
+function devConfigOverride(config) {
+  return config;
+}
+
+module.exports = devConfigOverride;

packages/react-scripts/config/webpack.config.prod.js

@@ -61,7 +61,7 @@ if (env['process.env'].NODE_ENV !== '"production"') {
 // This is the production configuration.
 // It compiles slowly and is focused on producing a fast and minimal bundle.
 // The development configuration is different and lives in a separate file.
-module.exports = {
+module.exports = require('./webpack.config.prod.override')({
   // Don't attempt to continue if there are any errors.
   bail: true,
   // We generate sourcemaps in production. This is slow but gives good results.
@@ -277,4 +277,4 @@ module.exports = {
     net: 'empty',
     tls: 'empty'
   }
-};
+});

packages/react-scripts/config/webpack.config.prod.override.js

@@ -0,0 +1,5 @@
+function prodConfigOverride(config) {
+  return config;
+}
+
+module.exports = prodConfigOverride;

packages/react-scripts/scripts/eject.js

@@ -54,7 +54,9 @@ prompt(
     path.join('config', 'paths.js'),
     path.join('config', 'polyfills.js'),
     path.join('config', 'webpack.config.dev.js'),
+    path.join('config', 'webpack.config.dev.override.js'),
     path.join('config', 'webpack.config.prod.js'),
+    path.join('config', 'webpack.config.prod.override.js'),
     path.join('config', 'jest', 'cssTransform.js'),
     path.join('config', 'jest', 'fileTransform.js'),
     path.join('scripts', 'build.js'),