Custom Webpack Config

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You can customize Storybook’s webpack setup by providing a webpack field in main.js file. The value should be an async function that receives a webpack config and eventually returns a webpack config.

Storybook has its own Webpack setup and a dev server. The webpack config is configurable, and the default can depend on which framework you’re using and whether you’ve used a generator like Create React App or Angular CLI etc.

We’re trying to make storybook more zero-config over time, help to hook into the config of generators is very welcome.

This is what the config for storybook looks like when using CRA in dev-mode:
{
mode: 'development',
bail: false,
devtool: '#cheap-module-source-map',
entry: [
  '@storybook/core/dist/server/common/polyfills.js',
  '@storybook/core/dist/server/preview/globals.js',
  '<your-storybook-dir>/preview.js',
  'webpack-hot-middleware/client.js?reload=true',
],
output: {
  path: './',
  filename: '[name].[hash].bundle.js',
  publicPath: '',
},
plugins: [
  HtmlWebpackPlugin {
    options: {
      template: '@storybook/core/dist/server/templates/index.ejs',
      templateContent: false,
      templateParameters: [Function: templateParameters],
      filename: 'iframe.html',
      hash: false,
      inject: false,
      compile: true,
      favicon: false,
      minify: undefined,
      cache: true,
      showErrors: true,
      chunks: 'all',
      excludeChunks: [],
      chunksSortMode: 'none',
      meta: {},
      title: 'Webpack App',
      xhtml: false,
      alwaysWriteToDisk: true,
    },
  },
  DefinePlugin {
    definitions: {
      'process.env': {
        NODE_ENV: '"development"',
        NODE_PATH: '""',
        PUBLIC_URL: '"."',
        '<storybook-environment-variables>'
        '<dotenv-environment-variables>'
      },
    },
  },
  WatchMissingNodeModulesPlugin {
    nodeModulesPath: './node_modules',
  },
  HotModuleReplacementPlugin {},
  CaseSensitivePathsPlugin {},
  ProgressPlugin {},
  DefinePlugin {
    definitions: {
      '<storybook-environment-variables>'
      '<dotenv-environment-variables>'
    },
  },
],
module: {
  rules: [
    { test: /\.(mjs|jsx?)$/,
      use: [
        { loader: 'babel-loader', options:
          { cacheDirectory: './node_modules/.cache/storybook',
            presets: [
              [ './node_modules/@babel/preset-env/lib/index.js', { shippedProposals: true, useBuiltIns: 'usage', corejs: '3' } ],
              './node_modules/@babel/preset-react/lib/index.js',
              './node_modules/@babel/preset-flow/lib/index.js',
            ],
            plugins: [
              './node_modules/@babel/plugin-proposal-object-rest-spread/lib/index.js',
              './node_modules/@babel/plugin-proposal-class-properties/lib/index.js',
              './node_modules/@babel/plugin-syntax-dynamic-import/lib/index.js',
              [ './node_modules/babel-plugin-emotion/dist/babel-plugin-emotion.cjs.js', { sourceMap: true, autoLabel: true } ],
              './node_modules/babel-plugin-macros/dist/index.js',
              './node_modules/@babel/plugin-transform-react-constant-elements/lib/index.js',
              './node_modules/babel-plugin-add-react-displayname/index.js',
              [ './node_modules/babel-plugin-react-docgen/lib/index.js', { DOC_GEN_COLLECTION_NAME: 'STORYBOOK_REACT_CLASSES' } ],
            ],
          },
        },
      ],
      include: [ './' ],
      exclude: [ './node_modules' ],
    },
    { test: /\.md$/,
      use: [
        { loader: './node_modules/raw-loader/index.js' },
      ],
    },
    { test: /\.css$/,
      use: [
        './node_modules/style-loader/index.js',
        { loader: './node_modules/css-loader/dist/cjs.js', options: { importLoaders: 1 } },
        { loader: './node_modules/postcss-loader/src/index.js', options: { ident: 'postcss', postcss: {}, plugins: [Function: plugins] } },
      ],
    },
    { test: /\.(svg|ico|jpg|jpeg|png|gif|eot|otf|webp|ttf|woff|woff2|cur|ani)(\?.*)?$/,
      loader: './node_modules/file-loader/dist/cjs.js',
      query: { name: 'static/media/[name].[hash:8].[ext]' },
    },
    { test: /\.(mp4|webm|wav|mp3|m4a|aac|oga)(\?.*)?$/,
      loader: './node_modules/url-loader/dist/cjs.js',
      query: { limit: 10000, name: 'static/media/[name].[hash:8].[ext]' },
    },
  ],
},
resolve: {
  extensions: [ '.mjs', '.js', '.jsx', '.json' ],
  modules: [ 'node_modules' ],
  mainFields: [ 'browser', 'main', 'module' ],
  alias: {
    'core-js': './node_modules/core-js',
    react: './node_modules/react',
    'react-dom': './node_modules/react-dom',
  },
},
optimization: {
  splitChunks: { chunks: 'all' },
  runtimeChunk: true,
  minimizer: [ [Object] ],
},
performance: { hints: false },
}

Debug the default webpack config

To effectively customize the webpack config, you might need to get the full default config it's using.
  • Create a .storybook/main.js file.
  • Edit its contents:

    module.exports = {
    webpackFinal: (config) => console.dir(config, { depth: null }) || config,
    };
  • Then run storybook:

    yarn storybook --debug-webpack

The console should log the entire config, for you to inspect.

Examples

The value should export a function, it’s first argument, is the config that storybook would use, if you were to not customize it. The second argument is an options object from storybook, this will have information about where config came from, whether we’re in production of development mode etc.

For example, here’s a .storybook/main.js to add SASS support:

const path = require('path');

// Export a function. Accept the base config as the only param.
module.exports = {
  webpackFinal: async (config, { configType }) => {
    // `configType` has a value of 'DEVELOPMENT' or 'PRODUCTION'
    // You can change the configuration based on that.
    // 'PRODUCTION' is used when building the static version of storybook.

    // Make whatever fine-grained changes you need
    config.module.rules.push({
      test: /\.scss$/,
      use: ['style-loader', 'css-loader', 'sass-loader'],
      include: path.resolve(__dirname, '../'),
    });

    // Return the altered config
    return config;
  },
};

Storybook uses the config returned from the above function to render your components in Storybook’s “preview” iframe. Note that Storybook has a completely separate webpack config for its own UI (also referred to as the “manager”), so the customizations you make only applies to the rendering of your stories, i.e. you can completely replace config.module.rules if you want.

Nevertheless, edit config with care. Make sure to preserve the following config options:

  • entry
  • output

Furthermore, config requires the HtmlWebpackplugin to generate the preview page, so rather than overwriting config.plugins you should probably append to it (or overwrite it with care), see Issue #6020 for examples:

module.exports = {
webpackFinal: (config) => {
  config.plugins.push(...);
  return config;
},
}

Finally, if your custom webpack config uses a loader that does not explicitly include specific file extensions via the test property, it is necessary to exclude the .ejs file extension from that loader.

If you’re using a non-standard Storybook config directory, you should put main.js there instead of .storybook and update the include path to make sure that it resolves to your project root.

Using Your Existing Config

If you have an existing webpack config for your project and want to reuse this app’s configuration, you can either:

  • Import your main webpack config into Storybook’s .storybook/main.js and merge the 2 configs.

Example replacing the loaders from storybook with the loaders from your app’s webpack.config.js

const path = require('path');

// your app's webpack.config.js
const custom = require('../webpack.config.js');

module.exports = {
  webpackFinal: (config) => {
    return { ...config, module: { ...config.module, rules: custom.module.rules } };
  },
};