astro/packages/integrations/netlify/README.md

# @astrojs/netlify

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

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

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

## Why Astro Netlify

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.

[Netlify](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 Netlify.

## Installation

Add the Netlify 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.

```sh
# Using NPM
npx astro add netlify
# Using Yarn
yarn astro add netlify
# Using PNPM
pnpm astro add netlify
```

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

1. Install the Netlify 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/netlify
   ```

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

   ```js ins={3, 6-7}
   // astro.config.mjs
   import { defineConfig } from 'astro/config';
   import netlify from '@astrojs/netlify/functions';

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

### Edge Functions

Netlify has two serverless platforms, Netlify Functions and [Netlify's experimental Edge Functions](https://docs.netlify.com/netlify-labs/experimental-features/edge-functions/#app). With Edge Functions your code is distributed closer to your users, lowering latency.

To deploy with Edge Functions, use `netlify/edge-functions` in the Astro config file instead of `netlify/functions`.

```js ins={3}
// astro.config.mjs
import { defineConfig } from 'astro/config';
import netlify from '@astrojs/netlify/edge-functions';

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

### Per-page functions

The Netlify adapter builds to a single function by default. Astro 2.7 added support for splitting your build into separate entry points per page. If you use this configuration, the Netlify adapter will generate a separate function for each page. This can help reduce the size of each function so they are only bundling code used on that page.

```js
// astro.config.mjs
import { defineConfig } from 'astro/config';
import netlify from '@astrojs/netlify/functions';

export default defineConfig({
  output: 'server',
  adapter: netlify(),
  build: {
    split: true,
  },
});
```

### Static sites

For static sites you usually don't need an adapter. However, if you use `redirects` configuration (experimental) in your Astro config, the Netlify adapter can be used to translate this to the proper `_redirects` format.

```js
import { defineConfig } from 'astro/config';
import netlify from '@astrojs/netlify/static';

export default defineConfig({
  adapter: netlify(),

  redirects: {
    '/blog/old-post': '/blog/new-post',
  },
  experimental: {
    redirects: true,
  },
});
```

Once you run `astro build` there will be a `dist/_redirects` file. Netlify will use that to properly route pages in production.

> **Note**
> You can still include a `public/_redirects` file for manual redirects. Any redirects you specify in the redirects config are appended to the end of your own.


### Edge Middleware with Astro middleware

The `@astrojs/netlify/functions` adapter can automatically create an edge function that will act as "Edge Middleware", from an Astro middleware in your code base.

This is an opt-in feature and the `build.excludeMiddleware` option needs to be set to `true`:

```js
// astro.config.mjs
import { defineConfig } from 'astro/config';
import netlify from '@astrojs/netlify/functions';
export default defineConfig({
  output: 'server',
  adapter: netlify(),
  build: {
    excludeMiddleware: true,
  },
});
```

Optionally, you can create a file recognized by the adapter named `netlify-edge-middleware.(js|ts)` in the [`srcDir`](https://docs.astro.build/en/reference/configuration-reference/#srcdir) folder to create [`Astro.locals`](https://docs.astro.build/en/reference/api-reference/#astrolocals).

Typings require the [`https://edge.netlify.com`](https://docs.netlify.com/edge-functions/api/#reference) types.

> Netlify edge functions run in a Deno environment, so you would need to import types using URLs.
> 
> You can find more in the [Netlify documentation page](https://docs.netlify.com/edge-functions/api/#runtime-environment)

```ts
// src/netlify-edge-middleware.ts
import type { Context } from "https://edge.netlify.com";

export default function ({ request, context }: { request: Request, context: Context }): object {
  // do something with request and context
  return {
    title: "Spider-man's blog",
  };
}
```

The data returned by this function will be passed to Astro middleware.

The function:

- must export a **default** function;
- must **return** an `object`;
- accepts an object with a `request` and `context` as properties;
- `request` is typed as [`Request`](https://developer.mozilla.org/en-US/docs/Web/API/Request);
- `context` is typed as [`Context`](https://docs.netlify.com/edge-functions/api/#edge-function-types);

#### Limitations and constraints

When you opt-in to this feature, there are a few constraints to note:

- The Edge middleware will always be the **first** function to receive the `Request` and the last function to receive `Response`. This is an architectural constraint that follows the [boundaries set by Netlify](https://docs.netlify.com/edge-functions/overview/#use-cases).
- Only `request` and `context` may be used to produce an `Astro.locals` object. Operations like redirects, etc. should be delegated to Astro middleware.
- `Astro.locals` **must be serializable**. Failing to do so will result in a **runtime error**. This means that you **cannot** store complex types like `Map`, `function`, `Set`, etc.


## Usage

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

After [performing a build](https://docs.astro.build/en/guides/deploy/#building-your-site-locally) the `netlify/` folder will contain [Netlify Functions](https://docs.netlify.com/functions/overview/) in the `netlify/functions/` folder.

Now you can deploy. Install the [Netlify CLI](https://docs.netlify.com/cli/get-started/) and run:

```sh
netlify deploy --build
```

The [Netlify Blog post on Astro](https://www.netlify.com/blog/how-to-deploy-astro/) and the [Netlify Documentation](https://docs.netlify.com/integrations/frameworks/astro/) provide more information on how to use this integration to deploy to Netlify.

## Configuration

To configure this adapter, pass an object to the `netlify()` function call in `astro.config.mjs` - there's only one possible configuration option:

### dist

We build to the `dist` directory at the base of your project. To change this, use the `dist` option:

```js
// astro.config.mjs
import { defineConfig } from 'astro/config';
import netlify from '@astrojs/netlify/functions';

export default defineConfig({
  output: 'server',
  adapter: netlify({
    dist: new URL('./dist/', import.meta.url),
  }),
});
```

And then point to the dist in your `netlify.toml`:

```toml title="netlify.toml"
[functions]
directory = "dist/functions"
```

### builders

[Netlify On-demand Builders](https://docs.netlify.com/configure-builds/on-demand-builders/) are serverless functions used to build and cache page content on Netlify’s Edge CDN. You can enable these functions with the `builders` option:

```js
// astro.config.mjs
import { defineConfig } from 'astro/config';
import netlify from '@astrojs/netlify/functions';

export default defineConfig({
  output: 'server',
  adapter: netlify({
    builders: true,
  }),
});
```

On-demand Builders are only available with the `@astrojs/netlify/functions` adapter and are not compatible with Edge Functions.

### binaryMediaTypes

> This option is only needed for the Functions adapter and is not needed for Edge Functions.

Netlify Functions requires binary data in the `body` to be base64 encoded. The `@astrojs/netlify/functions` adapter handles this automatically based on the `Content-Type` header.

We check for common mime types for audio, image, and video files. To include specific mime types that should be treated as binary data, include the `binaryMediaTypes` option with a list of binary mime types.

```js {12}
// src/pages/image.jpg.ts

import fs from 'node:fs';

export function get() {
  const buffer = fs.readFileSync('../image.jpg');

  // Return the buffer directly, @astrojs/netlify will base64 encode the body
  return new Response(buffer, {
    status: 200,
    headers: {
      'content-type': 'image/jpeg',
    },
  });
}
```

## Examples

- The [Astro Netlify Edge Starter](https://github.com/sarahetter/astro-netlify-edge-starter) provides an example and a guide in the README.

- [Browse Astro Netlify projects on GitHub](https://github.com/search?q=%22%40astrojs%2Fnetlify%22+filename%3Apackage.json&type=Code) for more examples!

## Troubleshooting

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

You can also check our [Astro Integration Documentation][astro-integration] for more on integrations.

## 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/