fix: correctly handle pathnames found in the _redirects file

.changeset/fuzzy-maps-sort.md

@@ -0,0 +1,5 @@
+---
+'@sveltejs/adapter-cloudflare': patch
+---
+
+fix: error if `_routes.json` is in the `/static` public directory

.changeset/quiet-onions-accept.md

@@ -0,0 +1,5 @@
+---
+'@sveltejs/adapter-cloudflare': patch
+---
+
+fix: correctly handle pathnames found in the `_redirects` file

documentation/docs/25-build-and-deploy/60-adapter-cloudflare.md

@@ -72,6 +72,7 @@ Only for Cloudflare Pages. Allows you to customise the [`_routes.json`](https://
 - `exclude` defines routes that will _not_ invoke a function — this is a faster and cheaper way to serve your app's static assets. This array can include the following special values:
 	- `<build>` contains your app's build artifacts (the files generated by Vite)
 	- `<files>` contains the contents of your `static` directory
+	- `<redirects>` contains a list of pathnames from your [`_redirects` file](https://developers.cloudflare.com/pages/configuration/redirects/) at the root
 	- `<prerendered>` contains a list of prerendered pages
 	- `<all>` (the default) contains all of the above
 

packages/adapter-cloudflare/index.d.ts

@@ -67,6 +67,10 @@ export interface AdapterOptions {
 	platformProxy?: GetPlatformProxyOptions;
 }
 
+/**
+ * The JSON format of the {@link https://developers.cloudflare.com/pages/functions/routing/#create-a-_routesjson-file | `_routes.json`}
+ * file that controls when the Cloudflare Pages Function is invoked.
+ */
 export interface RoutesJSONSpec {
 	version: 1;
 	description: string;

packages/adapter-cloudflare/index.js

@@ -1,15 +1,19 @@
-import { copyFileSync, existsSync, writeFileSync } from 'node:fs';
 import path from 'node:path';
 import process from 'node:process';
+import { copyFileSync, existsSync, readFileSync, writeFileSync } from 'node:fs';
 import { fileURLToPath } from 'node:url';
+import { get_routes_json, parse_redirects } from './utils.js';
 import { getPlatformProxy, unstable_readConfig } from 'wrangler';
 
 /** @type {import('./index.js').default} */
 export default function (options = {}) {
 	return {
 		name: '@sveltejs/adapter-cloudflare',
 		async adapt(builder) {
-			if (existsSync('_routes.json')) {
+			if (
+				existsSync('_routes.json') ||
+				existsSync(`${builder.config.kit.files.assets}/_routes.json`)
+			) {
 				throw new Error(
 					"Cloudflare Pages' _routes.json should be configured in svelte.config.js. See https://svelte.dev/docs/kit/adapter-cloudflare#Options-routes"
 				);
@@ -67,7 +71,9 @@ export default function (options = {}) {
 				building_for_cloudflare_pages ||
 				wrangler_config.assets?.not_found_handling === '404-page'
 			) {
-				// generate plaintext 404.html first which can then be overridden by prerendering, if the user defined such a page
+				// generate plaintext 404.html first which can then be overridden by prerendering, if the user defined such a page.
+				// This file is served when a request fails to match an asset.
+				// If we're building for Cloudflare Pages, it's only served when a request matches an entry in `routes.exclude`
 				const fallback = path.join(assets_dest, '404.html');
 				if (options.fallback === 'spa') {
 					await builder.generateFallback(fallback);
@@ -104,28 +110,43 @@ export default function (options = {}) {
 			});
 
 			// _headers
-			if (existsSync('_headers')) {
-				copyFileSync('_headers', `${dest}/_headers`);
+			const headers_src = '_headers';
+			const headers_dest = `${dest}/_headers`;
+			if (existsSync(headers_src)) {
+				copyFileSync(headers_src, headers_dest);
 			}
-			writeFileSync(`${dest}/_headers`, generate_headers(builder.getAppPath()), { flag: 'a' });
+			writeFileSync(headers_dest, generate_headers(builder.getAppPath()), { flag: 'a' });
 
 			// _redirects
-			if (existsSync('_redirects')) {
-				copyFileSync('_redirects', `${dest}/_redirects`);
+			const redirects_src = '_redirects';
+			const redirects_dest = `${dest}/_redirects`;
+			if (existsSync(redirects_src)) {
+				copyFileSync(redirects_src, redirects_dest);
 			}
 			if (builder.prerendered.redirects.size > 0) {
-				writeFileSync(`${dest}/_redirects`, generate_redirects(builder.prerendered.redirects), {
+				writeFileSync(redirects_dest, generate_redirects(builder.prerendered.redirects), {
 					flag: 'a'
 				});
 			}
 
-			writeFileSync(`${dest}/.assetsignore`, generate_assetsignore(), { flag: 'a' });
-
 			if (building_for_cloudflare_pages) {
+				// _routes.json
+				/** @type {string[]} */
+				let redirects = [];
+				if (existsSync(redirects_dest)) {
+					const redirect_rules = readFileSync(redirects_dest, 'utf8');
+					redirects = parse_redirects(redirect_rules);
+				}
 				writeFileSync(
 					`${dest}/_routes.json`,
-					JSON.stringify(get_routes_json(builder, client_assets, options.routes ?? {}), null, '\t')
+					JSON.stringify(
+						get_routes_json(builder, client_assets, redirects, options.routes ?? {}),
+						null,
+						'\t'
+					)
 				);
+			} else {
+				writeFileSync(`${dest}/.assetsignore`, generate_assetsignore(), { flag: 'a' });
 			}
 		},
 		emulate() {
@@ -167,68 +188,9 @@ export default function (options = {}) {
 }
 
 /**
- * @param {import('@sveltejs/kit').Builder} builder
- * @param {string[]} assets
- * @param {import('./index.js').AdapterOptions['routes']} routes
- * @returns {import('./index.js').RoutesJSONSpec}
+ * @param {string} app_dir
+ * @returns {string}
  */
-function get_routes_json(builder, assets, { include = ['/*'], exclude = ['<all>'] }) {
-	if (!Array.isArray(include) || !Array.isArray(exclude)) {
-		throw new Error('routes.include and routes.exclude must be arrays');
-	}
-
-	if (include.length === 0) {
-		throw new Error('routes.include must contain at least one route');
-	}
-
-	if (include.length > 100) {
-		throw new Error('routes.include must contain 100 or fewer routes');
-	}
-
-	exclude = exclude
-		.flatMap((rule) => (rule === '<all>' ? ['<build>', '<files>', '<prerendered>'] : rule))
-		.flatMap((rule) => {
-			if (rule === '<build>') {
-				return [`/${builder.getAppPath()}/immutable/*`, `/${builder.getAppPath()}/version.json`];
-			}
-
-			if (rule === '<files>') {
-				return assets
-					.filter(
-						(file) =>
-							!(
-								file.startsWith(`${builder.config.kit.appDir}/`) ||
-								file === '_headers' ||
-								file === '_redirects'
-							)
-					)
-					.map((file) => `${builder.config.kit.paths.base}/${file}`);
-			}
-
-			if (rule === '<prerendered>') {
-				return builder.prerendered.paths;
-			}
-
-			return rule;
-		});
-
-	const excess = include.length + exclude.length - 100;
-	if (excess > 0) {
-		const message = `Cloudflare Pages Functions' includes/excludes exceeds _routes.json limits (see https://developers.cloudflare.com/pages/platform/functions/routing/#limits). Dropping ${excess} exclude rules — this will cause unnecessary function invocations.`;
-		builder.log.warn(message);
-
-		exclude.length -= excess;
-	}
-
-	return {
-		version: 1,
-		description: 'Generated by @sveltejs/adapter-cloudflare',
-		include,
-		exclude
-	};
-}
-
-/** @param {string} app_dir */
 function generate_headers(app_dir) {
 	return `
 # === START AUTOGENERATED SVELTE IMMUTABLE HEADERS ===
@@ -242,7 +204,10 @@ function generate_headers(app_dir) {
 `.trimEnd();
 }
 
-/** @param {Map<string, { status: number; location: string }>} redirects */
+/**
+ * @param {Map<string, { status: number; location: string }>} redirects
+ * @returns {string}
+ */
 function generate_redirects(redirects) {
 	const rules = Array.from(
 		redirects.entries(),
@@ -256,14 +221,17 @@ ${rules}
 `.trimEnd();
 }
 
+/**
+ * @returns {string}
+ */
 function generate_assetsignore() {
 	// this comes from https://github.com/cloudflare/workers-sdk/blob/main/packages/create-cloudflare/templates-experimental/svelte/templates/static/.assetsignore
 	return `
 _worker.js
 _routes.json
 _headers
 _redirects
-`;
+`.trimEnd();
 }
 
 /**

packages/adapter-cloudflare/package.json

@@ -38,7 +38,9 @@
 		"format": "pnpm lint --write",
 		"check": "tsc --skipLibCheck",
 		"prepublishOnly": "pnpm build",
-		"test": "pnpm build && pnpm -r --workspace-concurrency 1 --filter=\"./test/**\" test"
+		"test:unit": "vitest run",
+		"test:e2e": "pnpm build && pnpm -r --workspace-concurrency 1 --filter=\"./test/**\" test",
+		"test": "pnpm test:unit && pnpm test:e2e"
 	},
 	"dependencies": {
 		"@cloudflare/workers-types": "^4.20250507.0",
@@ -49,7 +51,8 @@
 		"@sveltejs/kit": "workspace:^",
 		"@types/node": "^18.19.48",
 		"esbuild": "^0.25.4",
-		"typescript": "^5.3.3"
+		"typescript": "^5.3.3",
+		"vitest": "^3.1.1"
 	},
 	"peerDependencies": {
 		"@sveltejs/kit": "^2.0.0",

packages/adapter-cloudflare/tsconfig.json

@@ -15,5 +15,12 @@
 		"lib": ["es2021"],
 		"types": ["@cloudflare/workers-types"]
 	},
-	"include": ["index.js", "utils.js", "test/utils.js", "internal.d.ts", "src/worker.js"]
+	"include": [
+		"index.js",
+		"utils.js",
+		"utils.spec.js",
+		"test/utils.js",
+		"internal.d.ts",
+		"src/worker.js"
+	]
 }

packages/adapter-cloudflare/utils.js

@@ -0,0 +1,111 @@
+/**
+ * Extracts the redirect source from each line of a [_redirects](https://developers.cloudflare.com/pages/configuration/redirects/)
+ * file so we can exclude them in [_routes.json](https://developers.cloudflare.com/pages/functions/routing/#create-a-_routesjson-file)
+ * to ensure the redirect is invoked instead of the Cloudflare Worker.
+ * @param {string} file_contents
+ * @returns {string[]}
+ */
+export function parse_redirects(file_contents) {
+	/** @type {string[]} */
+	const redirects = [];
+
+	for (const line of file_contents.split('\n')) {
+		const content = line.trim();
+		if (!content) continue;
+
+		const [pathname] = line.split(' ');
+		// pathnames with placeholders are not supported
+		if (!pathname || pathname.includes('/:')) {
+			throw new Error(`The following _redirects rule cannot be excluded by _routes.json: ${line}`);
+		}
+		redirects.push(pathname);
+	}
+
+	return redirects;
+}
+
+/**
+ * Generates the [_routes.json](https://developers.cloudflare.com/pages/functions/routing/#create-a-_routesjson-file)
+ * file that dictates which routes invoke the Cloudflare Worker.
+ * @param {import('@sveltejs/kit').Builder} builder
+ * @param {string[]} client_assets
+ * @param {string[]} redirects
+ * @param {import('./index.js').AdapterOptions['routes']} routes
+ * @returns {import('./index.js').RoutesJSONSpec}
+ */
+export function get_routes_json(builder, client_assets, redirects, routes) {
+	const include = routes?.include ?? ['/*'];
+	let exclude = routes?.exclude ?? ['<all>'];
+
+	if (!Array.isArray(include) || !Array.isArray(exclude)) {
+		throw new Error('routes.include and routes.exclude must be arrays');
+	}
+
+	if (include?.length === 0) {
+		throw new Error('routes.include must contain at least one route');
+	}
+
+	if (include?.length > 100) {
+		throw new Error('routes.include must contain 100 or fewer routes');
+	}
+
+	/** @type {Set<string>} */
+	const transformed_rules = new Set();
+	for (const rule of exclude) {
+		if (rule === '<all>') {
+			transformed_rules.add('<build>');
+			transformed_rules.add('<files>');
+			transformed_rules.add('<prerendered>');
+			transformed_rules.add('<redirects>');
+		} else {
+			transformed_rules.add(rule);
+		}
+	}
+
+	/** @type {Set<string>} */
+	const excluded_routes = new Set();
+	for (const rule of transformed_rules) {
+		if (rule === '<build>') {
+			const app_path = builder.getAppPath();
+			excluded_routes.add(`/${app_path}/version.json`);
+			excluded_routes.add(`/${app_path}/immutable/*`);
+			continue;
+		}
+
+		if (rule === '<files>') {
+			for (const file of client_assets) {
+				if (file.startsWith(`${builder.config.kit.appDir}/`)) continue;
+				excluded_routes.add(`${builder.config.kit.paths.base}/${file}`);
+			}
+			continue;
+		}
+
+		if (rule === '<prerendered>') {
+			builder.prerendered.paths.forEach((path) => excluded_routes.add(path));
+			continue;
+		}
+
+		if (rule === '<redirects>') {
+			redirects.forEach((path) => excluded_routes.add(path));
+			continue;
+		}
+
+		excluded_routes.add(rule);
+	}
+	exclude = Array.from(excluded_routes);
+
+	const excess = include.length + exclude.length - 100;
+	if (excess > 0) {
+		builder.log.warn(
+			`Cloudflare Pages Functions' includes/excludes exceeds _routes.json limits (see https://developers.cloudflare.com/pages/platform/functions/routing/#limits). Dropping ${excess} exclude rules — this will cause unnecessary function invocations.`
+		);
+		exclude.length -= excess;
+	}
+
+	return {
+		version: 1,
+		description: 'Generated by @sveltejs/adapter-cloudflare',
+		include,
+		exclude
+	};
+}