Node compat

.changeset/chatty-pandas-swim.md

@@ -0,0 +1,5 @@
+---
+'@sveltejs/adapter-vercel': minor
+---
+
+feat: allow compatible subset of Node.js built-in modules when targeting edge functions

.changeset/two-pianos-obey.md

@@ -0,0 +1,5 @@
+---
+'@sveltejs/adapter-netlify': minor
+---
+
+feat: allow Node.js built-in modules when targeting edge functions

packages/adapter-netlify/index.js

@@ -1,6 +1,7 @@
 import { appendFileSync, existsSync, readdirSync, readFileSync, writeFileSync } from 'node:fs';
 import { dirname, join, resolve, posix } from 'node:path';
 import { fileURLToPath } from 'node:url';
+import { builtinModules } from 'node:module';
 import esbuild from 'esbuild';
 import toml from '@iarna/toml';
 
@@ -165,7 +166,12 @@ async function generate_edge_functions({ builder }) {
 		format: 'esm',
 		platform: 'browser',
 		sourcemap: 'linked',
-		target: 'es2020'
+		target: 'es2020',
+
+		// Node built-ins are allowed, but must be prefixed with `node:`
+		// https://docs.netlify.com/edge-functions/api/#runtime-environment
+		external: builtinModules.map((id) => `node:${id}`),
+		alias: Object.fromEntries(builtinModules.map((id) => [id, `node:${id}`]))
 	});
 
 	writeFileSync('.netlify/edge-functions/manifest.json', JSON.stringify(edge_manifest));

packages/adapter-vercel/index.js

@@ -18,6 +18,9 @@ const get_default_runtime = () => {
 	);
 };
 
+// https://vercel.com/docs/functions/edge-functions/edge-runtime#compatible-node.js-modules
+const compatible_node_modules = ['async_hooks', 'events', 'buffer', 'assert', 'util'];
+
 /** @type {import('.').default} **/
 const plugin = function (defaults = {}) {
 	if ('edge' in defaults) {
@@ -109,20 +112,61 @@ const plugin = function (defaults = {}) {
 					`export const manifest = ${builder.generateManifest({ relativePath, routes })};\n`
 				);
 
-				await esbuild.build({
-					entryPoints: [`${tmp}/edge.js`],
-					outfile: `${dirs.functions}/${name}.func/index.js`,
-					target: 'es2020', // TODO verify what the edge runtime supports
-					bundle: true,
-					platform: 'browser',
-					format: 'esm',
-					external: config.external,
-					sourcemap: 'linked',
-					banner: { js: 'globalThis.global = globalThis;' },
-					loader: {
-						'.wasm': 'copy'
+				try {
+					const result = await esbuild.build({
+						entryPoints: [`${tmp}/edge.js`],
+						outfile: `${dirs.functions}/${name}.func/index.js`,
+						target: 'es2020', // TODO verify what the edge runtime supports
+						bundle: true,
+						platform: 'browser',
+						format: 'esm',
+						external: [
+							...compatible_node_modules,
+							...compatible_node_modules.map((id) => `node:${id}`),
+							...(config.external || [])
+						],
+						sourcemap: 'linked',
+						banner: { js: 'globalThis.global = globalThis;' },
+						loader: {
+							'.wasm': 'copy'
+						}
+					});
+
+					if (result.warnings.length > 0) {
+						const formatted = await esbuild.formatMessages(result.warnings, {
+							kind: 'warning',
+							color: true
+						});
+
+						console.error(formatted.join('\n'));
 					}
-				});
+				} catch (error) {
+					for (const e of error.errors) {
+						for (const node of e.notes) {
+							const match =
+								/The package "(.+)" wasn't found on the file system but is built into node/.exec(
+									node.text
+								);
+
+							if (match) {
+								node.text = `Cannot use "${match[1]}" when deploying to Vercel Edge Functions.`;
+							}
+						}
+					}
+
+					const formatted = await esbuild.formatMessages(error.errors, {
+						kind: 'error',
+						color: true
+					});
+
+					console.error(formatted.join('\n'));
+
+					throw new Error(
+						`Bundling with esbuild failed with ${error.errors.length} ${
+							error.errors.length === 1 ? 'error' : 'errors'
+						}`
+					);
+				}
 
 				write(
 					`${dirs.functions}/${name}.func/.vc-config.json`,