fix(@astrojs/cloudflare): support for nodejs_compat (#8595)

Co-authored-by: Sarah Rainsberger <sarah@rainsberger.ca>
Co-authored-by: Florian Lefebvre <contact@florian-lefebvre.dev>

3 files changed, 71 insertions, 0 deletions

diff --git a/.changeset/fifty-weeks-bake.md b/.changeset/fifty-weeks-bake.md
new file mode 100644
index 000000000..714be802e
--- /dev/null
+++ b/.changeset/fifty-weeks-bake.md
@@ -0,0 +1,20 @@
+---
+'@astrojs/cloudflare': minor
+---
+
+Add support for the following Node.js Runtime APIs, which are availabe in [Cloudflare](https://developers.cloudflare.com/workers/runtime-apis/nodejs) using the `node:` syntax.
+
+- assert
+- AsyncLocalStorage
+- Buffer
+- Diagnostics Channel
+- EventEmitter
+- path
+- process
+- Streams
+- StringDecoder
+- util
+
+```js
+import { Buffer } from 'node:buffer';
+```
diff --git a/packages/integrations/cloudflare/README.md b/packages/integrations/cloudflare/README.md
index 27e621853..0d3312ce8 100644
--- a/packages/integrations/cloudflare/README.md
+++ b/packages/integrations/cloudflare/README.md
@@ -202,6 +202,33 @@ This will enable Cloudflare to serve files and process static redirects without
 
 See [Cloudflare's documentation](https://developers.cloudflare.com/pages/platform/functions/routing/#create-a-_routesjson-file) 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. 
+
+```js
+// 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](https://developers.cloudflare.com/workers/runtime-apis/nodejs).
+
 ## Troubleshooting
 
 For help, check out the `#support` channel on [Discord](https://astro.build/chat). Our friendly Support Squad members are here to help!
diff --git a/packages/integrations/cloudflare/src/index.ts b/packages/integrations/cloudflare/src/index.ts
index b64d986af..24c22d8f1 100644
--- a/packages/integrations/cloudflare/src/index.ts
+++ b/packages/integrations/cloudflare/src/index.ts
@@ -296,6 +296,18 @@ export default function createIntegration(args?: Options): AstroIntegration {
 						target: 'es2020',
 						platform: 'browser',
 						conditions: ['workerd', 'worker', 'browser'],
+						external: [
+							'node:assert',
+							'node:async_hooks',
+							'node:buffer',
+							'node:diagnostics_channel',
+							'node:events',
+							'node:path',
+							'node:process',
+							'node:stream',
+							'node:string_decoder',
+							'node:util',
+						],
 						entryPoints: entryPaths,
 						outdir: outputDir,
 						allowOverwrite: true,
@@ -357,6 +369,18 @@ export default function createIntegration(args?: Options): AstroIntegration {
 						target: 'es2020',
 						platform: 'browser',
 						conditions: ['workerd', 'worker', 'browser'],
+						external: [
+							'node:assert',
+							'node:async_hooks',
+							'node:buffer',
+							'node:diagnostics_channel',
+							'node:events',
+							'node:path',
+							'node:process',
+							'node:stream',
+							'node:string_decoder',
+							'node:util',
+						],
 						entryPoints: [entryPath],
 						outfile: buildPath,
 						allowOverwrite: true,