astro/packages/integrations/vercel/README.md

# @astrojs/vercel

This adapter allows Astro to deploy your SSR site to [Vercel](https://www.vercel.com/).

Learn how to deploy your Astro site in our [Vercel deployment guide](https://docs.astro.build/en/guides/deploy/vercel/).

- <strong>[Why Astro Vercel](#why-astro-vercel)</strong>
- <strong>[Installation](#installation)</strong>
- <strong>[Usage](#usage)</strong>
- <strong>[Configuration](#configuration)</strong>
- <strong>[Troubleshooting](#troubleshooting)</strong>
- <strong>[Contributing](#contributing)</strong>
- <strong>[Changelog](#changelog)</strong>

## Why Astro Vercel

If you're using Astro as a static site builder — its behavior out of the box — you don't need an adapter. 

If you wish to [use server-side rendering (SSR)](https://docs.astro.build/en/guides/server-side-rendering/), Astro requires an adapter that matches your deployment runtime.

[Vercel](https://www.netlify.com/) is a deployment platform that allows you to host your site by connecting directly to your GitHub repository.  This adapter enhances the Astro build process to prepare your project for deployment through Vercel.

## Installation

Add the Vercel adapter to enable SSR in your Astro project with the following `astro add` command. This will install the adapter and make the appropriate changes to your `astro.config.mjs` file in one step.

```bash
npx astro add vercel
```

If you prefer to install the adapter manually instead, complete the following two steps:

1. Install the Vercel adapter to your project’s dependencies using your preferred package manager. If you’re using npm or aren’t sure, run this in the terminal:

    ```bash
      npm install @astrojs/vercel
    ```

1. Add two new lines to your `astro.config.mjs` project configuration file.

    ```js title="astro.config.mjs" ins={2, 5-6}
    import { defineConfig } from 'astro/config';
    import netlify from '@astrojs/vercel/serverless';

    export default defineConfig({
      output: 'server',
      adapter: vercel(),
    });
    ```

### Targets

You can deploy to different targets:

- `edge`: SSR inside an [Edge function](https://vercel.com/docs/concepts/functions/edge-functions).
- `serverless`: SSR inside a [Node.js function](https://vercel.com/docs/concepts/functions/serverless-functions).
- `static`: generates a static website following Vercel's output formats, redirects, etc.

> **Note**: deploying to the Edge has [its limitations](https://vercel.com/docs/concepts/functions/edge-functions#known-limitations). An edge function can't be more than 1 MB in size and they don't support native Node.js APIs, among others.

You can change where to target by changing the import:

```js
import vercel from '@astrojs/vercel/edge';
import vercel from '@astrojs/vercel/serverless';
import vercel from '@astrojs/vercel/static';
```

## Usage

📚 **[Read the full deployment guide here.](https://docs.astro.build/en/guides/deploy/vercel/)**

You can deploy by CLI (`vercel deploy`) or by connecting your new repo in the [Vercel Dashboard](https://vercel.com/). Alternatively, you can create a production build locally:

```sh
astro build
vercel deploy --prebuilt
```

## Configuration

This adapter does not expose any configuration options.

## Troubleshooting

**A few known complex packages (example: [puppeteer](https://github.com/puppeteer/puppeteer)) do not support bundling and therefore will not work properly with this adapter.** By default, Vercel doesn't include npm installed files & packages from your project's `./node_modules` folder. To address this, the `@astrojs/vercel` adapter automatically bundles your final build output using `esbuild`.

For help, check out the `#support-threads` channel on [Discord](https://astro.build/chat). Our friendly Support Squad members are here to help!

## Contributing

This package is maintained by Astro's Core team. You're welcome to submit an issue or PR!

## Changelog

See [CHANGELOG.md](CHANGELOG.md) for a history of changes to this integration.

[astro-integration]: https://docs.astro.build/en/guides/integrations-guide/