astro/packages/integrations/cloudflare/README.md

@astrojs/cloudflare

An SSR adapter for use with Cloudflare Pages Functions targets. Write your code in Astro/Javascript and deploy to Cloudflare Pages.

Install

Add the Cloudflare 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.

# Using NPM
npx astro add cloudflare
# Using Yarn
yarn astro add cloudflare
# Using PNPM
pnpm astro add cloudflare

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

1. Add the Cloudflare 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:

npm install @astrojs/cloudflare

2. Add the following to your astro.config.mjs file:

  // astro.config.mjs
  import { defineConfig } from 'astro/config';
+ import cloudflare from '@astrojs/cloudflare';

  export default defineConfig({
+   output: 'server',
+   adapter: cloudflare(),
  });

Options

Mode

mode: "advanced" | "directory"

default "advanced"

Cloudflare Pages has 2 different modes for deploying functions, advanced mode which picks up the _worker.js in dist, or a directory mode where pages will compile the worker out of a functions folder in the project root. For most projects the adapter default of advanced will be sufficient; the dist folder will contain your compiled project.

mode:directory

Switching to directory mode allows you to use pages plugins such as Sentry or write custom code to enable logging.

// astro.config.mjs
export default defineConfig({
  adapter: cloudflare({ mode: 'directory' }),
});

In directory mode, the adapter will compile the client-side part of your app the same way as in advanced mode by default, but moves the worker script into a functions folder in the project root. In this case, the adapter will only ever place a [[path]].js in that folder, allowing you to add additional plugins and pages middleware which can be checked into version control.

To instead compile a separate bundle for each page, set the functionPerPath option in your Cloudflare adapter config. This option requires some manual maintenance of the functions folder. Files emitted by Astro will overwrite existing functions files with identical names, so you must choose unique file names for each file you manually add. Additionally, the adapter will never empty the functions folder of outdated files, so you must clean up the folder manually when you remove pages.

  // astro.config.mjs
  import {defineConfig} from "astro/config";
  import cloudflare from '@astrojs/cloudflare';

  export default defineConfig({
    adapter: cloudflare({
      mode: 'directory',
+     functionPerRoute: true
    })
  })

Note that this adapter does not support using Cloudflare Pages Middleware. Astro will bundle the Astro middleware into each page.

routes.strategy

routes.strategy: "auto" | "include" | "exclude"

default "auto"

Determines how routes.json will be generated if no custom _routes.json is provided.

There are three options available:

• "auto" (default): Will automatically select the strategy that generates the fewest entries. This should almost always be sufficient, so choose this option unless you have a specific reason not to.

• include: Pages and endpoints that are not pre-rendered are listed as include entries, telling Cloudflare to invoke these routes as functions. exclude entries are only used to resolve conflicts. Usually the best strategy when your website has mostly static pages and only a few dynamic pages or endpoints.

  Example: For src/pages/index.astro (static), src/pages/company.astro (static), src/pages/users/faq.astro (static) and /src/pages/users/[id].astro (SSR) this will produce the following _routes.json:

  {
    "version": 1,
    "include": [
      "/_image", // Astro's image endpoint
      "/users/*" // Dynamic route
    ],
    "exclude": [
      // Static routes that needs to be exempted from the dynamic wildcard route above
      "/users/faq/",
      "/users/faq/index.html"
    ]
  }
  

• exclude: Pre-rendered pages are listed as exclude entries (telling Cloudflare to handle these routes as static assets). Usually the best strategy when your website has mostly dynamic pages or endpoints and only a few static pages.

  Example: For the same pages as in the previous example this will produce the following _routes.json:

  {
    "version": 1,
    "include": [
      "/*" // Handle everything as function except the routes below
    ],
    "exclude": [
      // All static assets
      "/",
      "/company/",
      "/index.html",
      "/users/faq/",
      "/favicon.png",
      "/company/index.html",
      "/users/faq/index.html"
    ]
  }
  

routes.include

routes.include: string[]

default []

If you want to use the automatic _routes.json generation, but want to include additional routes (e.g. when having custom functions in the functions folder), you can use the routes.include option to add additional routes to the include array.

routes.exclude

routes.exclude: string[]

default []

If you want to use the automatic _routes.json generation, but want to exclude additional routes, you can use the routes.exclude option to add additional routes to the exclude array.

The following example automatically generates _routes.json while including and excluding additional routes. Note that that is only necessary if you have custom functions in the functions folder that are not handled by Astro.

  // astro.config.mjs
  export default defineConfig({
    adapter: cloudflare({
      mode: 'directory',
+     routes: {
+       strategy: 'include',
+       include: ['/users/*'], // handled by custom function: functions/users/[id].js
+       exclude: ['/users/faq'], // handled by static page: pages/users/faq.astro
+     },
    }),
  });

Enabling Preview

In order for preview to work you must install wrangler

pnpm install wrangler --save-dev

It's then possible to update the preview script in your package.json to "preview": "wrangler pages dev ./dist". This will allow you to run your entire application locally with Wrangler, which supports secrets, environment variables, KV namespaces, Durable Objects and all other supported Cloudflare bindings.

Access to the Cloudflare runtime

You can access all the Cloudflare bindings and environment variables from Astro components and API routes through Astro.locals.

If you're inside an .astro file, you access the runtime using the Astro.locals global:

const env = Astro.locals.runtime.env;

From an endpoint:

// src/pages/api/someFile.js
export function GET(context) {
  const runtime = context.locals.runtime;

  return new Response('Some body');
}

Depending on your adapter mode (advanced = worker, directory = pages), the runtime object will look a little different due to differences in the Cloudflare API.

If you're using the advanced runtime, you can type the runtime object as following:

// src/env.d.ts
/// <reference types="astro/client" />
import type { AdvancedRuntime } from '@astrojs/cloudflare';

type ENV = {
  SERVER_URL: string;
};

declare namespace App {
  interface Locals extends AdvancedRuntime<ENV> {
    user: {
      name: string;
      surname: string;
    };
  }
}

If you're using the directory runtime, you can type the runtime object as following:

// src/env.d.ts
/// <reference types="astro/client" />
import type { DirectoryRuntime } from '@astrojs/cloudflare';

type ENV = {
  SERVER_URL: string;
};

declare namespace App {
  interface Locals extends DirectoryRuntime<ENV> {
    user: {
      name: string;
      surname: string;
    };
  }
}

Environment Variables

See Cloudflare's documentation for working with environment variables.

// pages/[id].json.js

export function GET({ params }) {
  // Access environment variables per request inside a function
  const serverUrl = import.meta.env.SERVER_URL;
  const result = await fetch(serverUrl + "/user/" + params.id);
  return {
    body: await result.text(),
  };
}

cloudflare.runtime

runtime: "off" | "local" | "remote" default "off"

This optional flag enables the Astro dev server to populate environment variables and the Cloudflare Request Object, avoiding the need for Wrangler.

• local: environment variables are available, but the request object is populated from a static placeholder value.
• remote: environment variables and the live, fetched request object are available.
• off: the Astro dev server will populate neither environment variables nor the request object. Use Wrangler to access Cloudflare bindings and environment variables.

// astro.config.mjs
import { defineConfig } from 'astro/config';
import cloudflare from '@astrojs/cloudflare';

export default defineConfig({
  output: 'server',
  adapter: cloudflare({
    runtime: 'off' | 'local' | 'remote',
  }),
});

Wasm module imports

wasmModuleImports: boolean

default: false

Whether or not to import .wasm files directly as ES modules.

Add wasmModuleImports: true to astro.config.mjs to enable in both the Cloudflare build and the Astro dev server.

  // astro.config.mjs
  import {defineConfig} from "astro/config";
  import cloudflare from '@astrojs/cloudflare';

  export default defineConfig({
    adapter: cloudflare({
+     wasmModuleImports: true
    }),
    output: 'server'
  })

Once enabled, you can import a web assembly module in Astro with a .wasm?module import.

The following is an example of importing a Wasm module that then responds to requests by adding the request's number parameters together.

// pages/add/[a]/[b].js
import mod from '../util/add.wasm?module';

// instantiate ahead of time to share module
const addModule: any = new WebAssembly.Instance(mod);

export async function GET(context) {
  const a = Number.parseInt(context.params.a);
  const b = Number.parseInt(context.params.b);
  return new Response(`${addModule.exports.add(a, b)}`);
}

While this example is trivial, Wasm can be used to accelerate computationally intensive operations which do not involve significant I/O such as embedding an image processing library.

Headers, Redirects and function invocation routes

Cloudflare has support for adding custom headers, configuring static redirects and defining which routes should invoke functions. Cloudflare looks for _headers, _redirects, and _routes.json files in your build output directory to configure these features. This means they should be placed in your Astro project’s public/ directory.

Custom _routes.json

By default, @astrojs/cloudflare will generate a _routes.json file with include and exclude rules based on your applications's dynamic and static routes. This will enable Cloudflare to serve files and process static redirects without a function invocation. Creating a custom _routes.json will override this automatic optimization and, if not configured manually, cause function invocations that will count against the request limits of your Cloudflare plan.

See Cloudflare's documentation for more details.

Node.js compatibility

Astro's Cloudflare adapter allows you to use any Node.js runtime API supported by Cloudflare:

• assert
• AsyncLocalStorage
• Buffer
• Diagnostics Channel
• EventEmitter
• path
• process
• Streams
• StringDecoder
• util

To use these APIs, your page or endpoint must be server-side rendered (not pre-rendered) and must use the the import {} from 'node:*' import syntax.

// pages/api/endpoint.js
export const prerender = false;
import { Buffer } from 'node:buffer';

Additionally, you'll need to enable the Compatibility Flag in Cloudflare. The configuration for this flag may vary based on where you deploy your Astro site.

For detailed guidance, please refer to the Cloudflare documentation.

Troubleshooting

For help, check out the #support channel on Discord. Our friendly Support Squad members are here to help!

You can also check our Astro Integration Documentation for more on integrations.

Meaningful error messages

Currently, errors during running your application in Wrangler are not very useful, due to the minification of your code. For better debugging, you can add vite.build.minify = false setting to your astro.config.mjs.

  // astro.config.mjs
  export default defineConfig({
    adapter: cloudflare(),
    output: 'server',

+   vite: {
+     build: {
+       minify: false,
+     },
+   },
  });

Contributing

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