Fix Server Islands in Vercel (#11491)

* Fix Server Islands in Vercel

* Add a changeset

* Get server islands pattern from the segments

* Move getPattern so it can be used at runtime

* Fix build

.changeset/tidy-shrimps-grab.md

@@ -0,0 +1,7 @@
+---
+'astro': patch
+---
+
+Fix for Server Islands in Vercel adapter
+
+Vercel, and probably other adapters only allow pre-defined routes. This makes it so that the `astro:build:done` hook includes the `_server-islands/` route as part of the route data, which is used to configure available routes.

packages/astro/src/container/index.ts

@@ -20,7 +20,8 @@ import { Logger } from '../core/logger/core.js';
 import { nodeLogDestination } from '../core/logger/node.js';
 import { removeLeadingForwardSlash } from '../core/path.js';
 import { RenderContext } from '../core/render-context.js';
-import { getParts, getPattern, validateSegment } from '../core/routing/manifest/create.js';
+import { getParts, validateSegment } from '../core/routing/manifest/create.js';
+import { getPattern } from '../core/routing/manifest/pattern.js';
 import type { AstroComponentFactory } from '../runtime/server/index.js';
 import { ContainerPipeline } from './pipeline.js';
 

packages/astro/src/core/app/index.ts

@@ -88,7 +88,7 @@ export class App {
 
 	constructor(manifest: SSRManifest, streaming = true) {
 		this.#manifest = manifest;
-		this.#manifestData = injectDefaultRoutes({
+		this.#manifestData = injectDefaultRoutes(manifest, {
 			routes: manifest.routes.map((route) => route.routeData),
 		});
 		this.#baseWithoutTrailingSlash = removeTrailingForwardSlash(this.#manifest.base);

packages/astro/src/core/build/index.ts

@@ -32,6 +32,7 @@ import { collectPagesData } from './page-data.js';
 import { staticBuild, viteBuild } from './static-build.js';
 import type { StaticBuildOptions } from './types.js';
 import { getTimeStat } from './util.js';
+import { getServerIslandRouteData } from '../server-islands/endpoint.js';
 
 export interface BuildOptions {
 	/**
@@ -216,7 +217,10 @@ class AstroBuilder {
 			pages: pageNames,
 			routes: Object.values(allPages)
 				.flat()
-				.map((pageData) => pageData.route),
+				.map((pageData) => pageData.route).concat(
+					this.settings.config.experimental.serverIslands ?
+					[ getServerIslandRouteData(this.settings.config) ] : []
+				),
 			logging: this.logger,
 			cacheManifest: internals.cacheManifestUsed,
 		});

packages/astro/src/core/routing/default.ts

@@ -12,10 +12,10 @@ import {
 	ensure404Route,
 } from './astro-designed-error-pages.js';
 
-export function injectDefaultRoutes(manifest: ManifestData) {
-	ensure404Route(manifest);
-	ensureServerIslandRoute(manifest);
-	return manifest;
+export function injectDefaultRoutes(ssrManifest: SSRManifest, routeManifest: ManifestData) {
+	ensure404Route(routeManifest);
+	ensureServerIslandRoute(ssrManifest, routeManifest);
+	return routeManifest;
 }
 
 type DefaultRouteParams = {

packages/astro/src/core/routing/manifest/create.ts

@@ -22,6 +22,7 @@ import { removeLeadingForwardSlash, slash } from '../../path.js';
 import { resolvePages } from '../../util.js';
 import { routeComparator } from '../priority.js';
 import { getRouteGenerator } from './generator.js';
+import { getPattern } from './pattern.js';
 const require = createRequire(import.meta.url);
 
 interface Item {
@@ -70,59 +71,6 @@ export function getParts(part: string, file: string) {
 	return result;
 }
 
-export function getPattern(
-	segments: RoutePart[][],
-	base: AstroConfig['base'],
-	addTrailingSlash: AstroConfig['trailingSlash']
-) {
-	const pathname = segments
-		.map((segment) => {
-			if (segment.length === 1 && segment[0].spread) {
-				return '(?:\\/(.*?))?';
-			} else {
-				return (
-					'\\/' +
-					segment
-						.map((part) => {
-							if (part.spread) {
-								return '(.*?)';
-							} else if (part.dynamic) {
-								return '([^/]+?)';
-							} else {
-								return part.content
-									.normalize()
-									.replace(/\?/g, '%3F')
-									.replace(/#/g, '%23')
-									.replace(/%5B/g, '[')
-									.replace(/%5D/g, ']')
-									.replace(/[.*+?^${}()|[\]\\]/g, '\\$&');
-							}
-						})
-						.join('')
-				);
-			}
-		})
-		.join('');
-
-	const trailing =
-		addTrailingSlash && segments.length ? getTrailingSlashPattern(addTrailingSlash) : '$';
-	let initial = '\\/';
-	if (addTrailingSlash === 'never' && base !== '/') {
-		initial = '';
-	}
-	return new RegExp(`^${pathname || initial}${trailing}`);
-}
-
-function getTrailingSlashPattern(addTrailingSlash: AstroConfig['trailingSlash']): string {
-	if (addTrailingSlash === 'always') {
-		return '\\/$';
-	}
-	if (addTrailingSlash === 'never') {
-		return '$';
-	}
-	return '\\/?$';
-}
-
 export function validateSegment(segment: string, file = '') {
 	if (!file) file = segment;
 
@@ -486,7 +434,7 @@ function isStaticSegment(segment: RoutePart[]) {
  *   For example, `/foo/[bar]` and `/foo/[baz]` or `/foo/[...bar]` and `/foo/[...baz]`
  *     but not `/foo/[bar]` and `/foo/[...baz]`.
  */
-function detectRouteCollision(a: RouteData, b: RouteData, config: AstroConfig, logger: Logger) {
+function detectRouteCollision(a: RouteData, b: RouteData, _config: AstroConfig, logger: Logger) {
 	if (a.type === 'fallback' || b.type === 'fallback') {
 		// If either route is a fallback route, they don't collide.
 		// Fallbacks are always added below other routes exactly to avoid collisions.

packages/astro/src/core/routing/manifest/pattern.ts

@@ -0,0 +1,57 @@
+import type {
+	AstroConfig,
+	RoutePart,
+} from '../../../@types/astro.js';
+
+export function getPattern(
+	segments: RoutePart[][],
+	base: AstroConfig['base'],
+	addTrailingSlash: AstroConfig['trailingSlash']
+) {
+	const pathname = segments
+		.map((segment) => {
+			if (segment.length === 1 && segment[0].spread) {
+				return '(?:\\/(.*?))?';
+			} else {
+				return (
+					'\\/' +
+					segment
+						.map((part) => {
+							if (part.spread) {
+								return '(.*?)';
+							} else if (part.dynamic) {
+								return '([^/]+?)';
+							} else {
+								return part.content
+									.normalize()
+									.replace(/\?/g, '%3F')
+									.replace(/#/g, '%23')
+									.replace(/%5B/g, '[')
+									.replace(/%5D/g, ']')
+									.replace(/[.*+?^${}()|[\]\\]/g, '\\$&');
+							}
+						})
+						.join('')
+				);
+			}
+		})
+		.join('');
+
+	const trailing =
+		addTrailingSlash && segments.length ? getTrailingSlashPattern(addTrailingSlash) : '$';
+	let initial = '\\/';
+	if (addTrailingSlash === 'never' && base !== '/') {
+		initial = '';
+	}
+	return new RegExp(`^${pathname || initial}${trailing}`);
+}
+
+function getTrailingSlashPattern(addTrailingSlash: AstroConfig['trailingSlash']): string {
+	if (addTrailingSlash === 'always') {
+		return '\\/$';
+	}
+	if (addTrailingSlash === 'never') {
+		return '$';
+	}
+	return '\\/?$';
+}

packages/astro/src/core/server-islands/endpoint.ts

@@ -11,33 +11,41 @@ import {
 	renderTemplate,
 } from '../../runtime/server/index.js';
 import { createSlotValueFromString } from '../../runtime/server/render/slot.js';
+import { getPattern } from '../routing/manifest/pattern.js';
 
 export const SERVER_ISLAND_ROUTE = '/_server-islands/[name]';
 export const SERVER_ISLAND_COMPONENT = '_server-islands.astro';
 
-export function ensureServerIslandRoute(manifest: ManifestData) {
-	if (manifest.routes.some((route) => route.route === '/_server-islands/[name]')) {
-		return;
-	}
+type ConfigFields = Pick<SSRManifest, 'base' | 'trailingSlash'>;
 
+export function getServerIslandRouteData(config: ConfigFields) {
+	const segments = [
+		[{ content: '_server-islands', dynamic: false, spread: false }],
+		[{ content: 'name', dynamic: true, spread: false }],
+	];
 	const route: RouteData = {
 		type: 'page',
 		component: SERVER_ISLAND_COMPONENT,
 		generate: () => '',
 		params: ['name'],
-		segments: [
-			[{ content: '_server-islands', dynamic: false, spread: false }],
-			[{ content: 'name', dynamic: true, spread: false }],
-		],
-		// eslint-disable-next-line
-		pattern: /^\/_server-islands\/([^/]+?)$/,
+		segments,
+		pattern: getPattern(segments, config.base, config.trailingSlash),
 		prerender: false,
 		isIndex: false,
 		fallbackRoutes: [],
 		route: SERVER_ISLAND_ROUTE,
 	};
+	return route;
+}
 
-	manifest.routes.push(route);
+
+
+export function ensureServerIslandRoute(config: ConfigFields, routeManifest: ManifestData) {
+	if (routeManifest.routes.some((route) => route.route === '/_server-islands/[name]')) {
+		return;
+	}
+
+	routeManifest.routes.push(getServerIslandRouteData(config));
 }
 
 type RenderOptions = {

packages/astro/src/vite-plugin-astro-server/plugin.ts

@@ -35,7 +35,7 @@ export default function createVitePluginAstroServer({
 		configureServer(viteServer) {
 			const loader = createViteLoader(viteServer);
 			const manifest = createDevelopmentManifest(settings);
-			let manifestData: ManifestData = injectDefaultRoutes(
+			let manifestData: ManifestData = injectDefaultRoutes(manifest,
 				createRouteManifest({ settings, fsMod }, logger)
 			);
 			const pipeline = DevPipeline.create(manifestData, { loader, logger, manifest, settings });
@@ -46,7 +46,7 @@ export default function createVitePluginAstroServer({
 			function rebuildManifest(needsManifestRebuild: boolean) {
 				pipeline.clearRouteCache();
 				if (needsManifestRebuild) {
-					manifestData = injectDefaultRoutes(createRouteManifest({ settings }, logger));
+					manifestData = injectDefaultRoutes(manifest, createRouteManifest({ settings }, logger));
 					pipeline.setManifestData(manifestData);
 				}
 			}

packages/integrations/vercel/test/fixtures/server-islands/astro.config.mjs

@@ -0,0 +1,10 @@
+import vercel from '@astrojs/vercel/serverless';
+import { defineConfig } from 'astro/config';
+
+export default defineConfig({
+	output: "server",
+	adapter: vercel(),
+	experimental: {
+		serverIslands: true,
+	}
+});

packages/integrations/vercel/test/fixtures/server-islands/package.json

@@ -0,0 +1,10 @@
+{
+    "name": "@test/vercel-server-islands",
+    "version": "0.0.0",
+    "private": true,
+    "dependencies": {
+        "@astrojs/vercel": "workspace:*",
+        "astro": "workspace:*"
+    }
+}
+  

packages/integrations/vercel/test/fixtures/server-islands/src/components/Island.astro

@@ -0,0 +1 @@
+<h1>I'm an island</h1>

packages/integrations/vercel/test/fixtures/server-islands/src/pages/index.astro

@@ -0,0 +1,12 @@
+---
+import Island from '../components/Island.astro';
+---
+<html>
+	<head>
+		<title>One</title>
+	</head>
+	<body>
+		<h1>One</h1>
+		<Island server:defer />
+	</body>
+</html>

packages/integrations/vercel/test/server-islands.test.js

@@ -0,0 +1,29 @@
+import assert from 'node:assert/strict';
+import { before, describe, it } from 'node:test';
+import { loadFixture } from './test-utils.js';
+
+describe('Server Islands', () => {
+	/** @type {import('./test-utils.js').Fixture} */
+	let fixture;
+
+	before(async () => {
+		fixture = await loadFixture({
+			root: './fixtures/server-islands/',
+		});
+		await fixture.build();
+	});
+
+	it('server islands route is in the config', async () => {
+		const config = JSON.parse(
+			await fixture.readFile('../.vercel/output/config.json')
+		);
+		let found = null;
+		for(let route of config.routes) {
+		  if(route.src?.includes('_server-islands')) {
+		    found = route;
+		    break;
+		  }
+		}
+		assert.notEqual(found, null, 'Default server islands route included');
+	});
+});

pnpm-lock.yaml

@@ -5542,6 +5542,15 @@ importers:
         specifier: workspace:*
         version: link:../../../../../astro
 
+  packages/integrations/vercel/test/fixtures/server-islands:
+    dependencies:
+      '@astrojs/vercel':
+        specifier: workspace:*
+        version: link:../../..
+      astro:
+        specifier: workspace:*
+        version: link:../../../../../astro
+
   packages/integrations/vercel/test/fixtures/serverless-prerender:
     dependencies:
       '@astrojs/vercel':