feat: allow additional handlers in adapter-cloudflare-workers

.changeset/thirty-ghosts-cover.md

@@ -0,0 +1,6 @@
+---
+'@sveltejs/adapter-cloudflare-workers': minor
+'@sveltejs/adapter-cloudflare': minor
+---
+
+feat: allow additional handlers to be included in generated worker

documentation/docs/25-build-and-deploy/70-adapter-cloudflare-workers.md

@@ -36,6 +36,14 @@ export default {
 
 Path to your custom `wrangler.toml` or `wrangler.json` config file.
 
+### handlers
+
+Path to a file with additional [handlers](https://developers.cloudflare.com/workers/runtime-apis/handlers/) and (optionally) [Durable Objects](https://developers.cloudflare.com/durable-objects/) to be exported from the file the adapter generates. This allows you to, for example, include handlers for scheduled or queue triggers alongside the fetch handler your SvelteKit app.
+
+> [!NOTE] The adapter expects the `handlers` file to have a default export. If you only want to export a Durable Object, add `export default {};` to the file.
+
+> [!NOTE] The adapter will overwrite any [fetch handler](https://developers.cloudflare.com/workers/runtime-apis/handlers/fetch/) exported from the `handlers` file in the generated worker. Most uses for a fetch handler are covered by endpoints or server hooks, so you should use those instead.
+
 ### platformProxy
 
 Preferences for the emulated `platform.env` local bindings. See the [getPlatformProxy](https://developers.cloudflare.com/workers/wrangler/api/#syntax) Wrangler API documentation for a full list of options.

packages/adapter-cloudflare-workers/files/entry.js

@@ -1,7 +1,11 @@
 import { Server } from 'SERVER';
 import { manifest, prerendered, base_path } from 'MANIFEST';
+import handlers from 'HANDLERS';
 import { getAssetFromKV, mapRequestToAsset } from '@cloudflare/kv-asset-handler';
 import static_asset_manifest_json from '__STATIC_CONTENT_MANIFEST';
+
+export * from 'HANDLERS';
+
 const static_asset_manifest = JSON.parse(static_asset_manifest_json);
 
 const server = new Server(manifest);
@@ -12,6 +16,7 @@ const immutable = `${app_path}/immutable/`;
 const version_file = `${app_path}/version.json`;
 
 export default {
+	...handlers,
 	/**
 	 * @param {Request} req
 	 * @param {any} env

packages/adapter-cloudflare-workers/index.d.ts

@@ -6,6 +6,10 @@ export default function plugin(options?: AdapterOptions): Adapter;
 
 export interface AdapterOptions {
 	config?: string;
+	/**
+	 * Path to a file with additional {@link https://developers.cloudflare.com/workers/runtime-apis/handlers/ | handlers} and (optionally) {@link https://developers.cloudflare.com/durable-objects/ | Durable Objects} to be exported from the file the adapter generates.
+	 */
+	handlers?: string;
 	/**
 	 * Config object passed to {@link https://developers.cloudflare.com/workers/wrangler/api/#getplatformproxy | getPlatformProxy}
 	 * during development and preview.

packages/adapter-cloudflare-workers/index.js

@@ -1,6 +1,7 @@
 import { existsSync, readFileSync, writeFileSync } from 'node:fs';
-import { posix, dirname } from 'node:path';
+import { posix, dirname, resolve } from 'node:path';
 import { execSync } from 'node:child_process';
+import { cwd } from 'node:process';
 import esbuild from 'esbuild';
 import toml from '@iarna/toml';
 import { fileURLToPath } from 'node:url';
@@ -32,7 +33,7 @@ const compatible_node_modules = [
 ];
 
 /** @type {import('./index.js').default} */
-export default function ({ config = 'wrangler.toml', platformProxy = {} } = {}) {
+export default function ({ config = 'wrangler.toml', platformProxy = {}, handlers } = {}) {
 	return {
 		name: '@sveltejs/adapter-cloudflare-workers',
 
@@ -58,7 +59,8 @@ export default function ({ config = 'wrangler.toml', platformProxy = {} } = {})
 			builder.copy(`${files}/entry.js`, `${tmp}/entry.js`, {
 				replace: {
 					SERVER: `${relativePath}/index.js`,
-					MANIFEST: './manifest.js'
+					MANIFEST: './manifest.js',
+					HANDLERS: './_handlers.js'
 				}
 			});
 
@@ -78,6 +80,20 @@ export default function ({ config = 'wrangler.toml', platformProxy = {} } = {})
 					`export const base_path = ${JSON.stringify(builder.config.kit.paths.base)};\n`
 			);
 
+			if (handlers) {
+				// TODO: find a more robust way to resolve files relative to svelte.config.js
+				const handlers_file = resolve(cwd(), handlers);
+				writeFileSync(
+					`${tmp}/_handlers.js`,
+					`import handlers from "${handlers_file}";\n\n` +
+						`export * from "${handlers_file}";\n\n` +
+						'export default handlers;'
+				);
+			} else {
+				// The handlers file must export a plain object as its default export.
+				writeFileSync(`${tmp}/_handlers.js`, 'export default {};');
+			}
+
 			const external = ['__STATIC_CONTENT_MANIFEST', 'cloudflare:*'];
 			if (compatibility_flags && compatibility_flags.includes('nodejs_compat')) {
 				external.push(...compatible_node_modules.map((id) => `node:${id}`));

packages/adapter-cloudflare-workers/placeholders.d.ts

@@ -14,3 +14,11 @@ declare module '__STATIC_CONTENT_MANIFEST' {
 	const json: string;
 	export default json;
 }
+
+declare module 'HANDLERS' {
+	import { ExportedHandler } from '@cloudflare/workers-types';
+
+	const handlers: Omit<ExportedHandler, 'fetch'>;
+
+	export default handlers;
+}