---
title: 'env'
---

Parent: [main.js|ts configuration](./main-config.md)

Type: `(config: { [key: string]: string }) => { [key: string]: string }`

Defines custom Storybook [environment variables](../configure/environment-variables.md#using-storybook-configuration).

<!-- prettier-ignore-start -->

<CodeSnippets
  paths={[
    'common/main-config-env.js.mdx',
    'common/main-config-env.ts.mdx',
  ]}
/>

<!-- prettier-ignore-end -->