refactor: singular middleware (#9776)

* per-route middleware -> singular middleware

* add changeset

* emit middleware.mjs only when user middleware exists

* Apply suggestions from code review

.changeset/twenty-papayas-agree.md

@@ -0,0 +1,5 @@
+---
+"astro": patch
+---
+
+Simplifies internals that handle middleware.

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

@@ -18,6 +18,8 @@ export function deserializeManifest(serializedManifest: SerializedSSRManifest):
 	const clientDirectives = new Map(serializedManifest.clientDirectives);
 
 	return {
+		// in case user middleware exists, this no-op middleware will be reassigned (see plugin-ssr.ts)
+		middleware(_, next) { return next() },
 		...serializedManifest,
 		assets,
 		componentMetadata,

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

@@ -77,7 +77,7 @@ export interface RenderErrorOptions {
 	response?: Response;
 	status: 404 | 500;
 	/**
-	 * Whether to skip onRequest() while rendering the error page. Defaults to false.
+	 * Whether to skip middleware while rendering the error page. Defaults to false.
 	 */
 	skipMiddleware?: boolean;
 }
@@ -260,16 +260,10 @@ export class App {
 				this.#manifest.buildFormat
 			);
 			if (i18nMiddleware) {
-				if (mod.onRequest) {
-					this.#pipeline.setMiddlewareFunction(sequence(i18nMiddleware, mod.onRequest));
-				} else {
-					this.#pipeline.setMiddlewareFunction(i18nMiddleware);
-				}
+				this.#pipeline.setMiddlewareFunction(sequence(i18nMiddleware, this.#manifest.middleware));
 				this.#pipeline.onBeforeRenderRoute(i18nPipelineHook);
 			} else {
-				if (mod.onRequest) {
-					this.#pipeline.setMiddlewareFunction(mod.onRequest);
-				}
+				this.#pipeline.setMiddlewareFunction(this.#manifest.middleware);
 			}
 			response = await this.#pipeline.renderRoute(renderContext, pageModule);
 		} catch (err: any) {
@@ -429,8 +423,8 @@ export class App {
 					status
 				);
 				const page = (await mod.page()) as any;
-				if (skipMiddleware === false && mod.onRequest) {
-					this.#pipeline.setMiddlewareFunction(mod.onRequest);
+				if (skipMiddleware === false) {
+					this.#pipeline.setMiddlewareFunction(this.#manifest.middleware);
 				}
 				if (skipMiddleware) {
 					// make sure middleware set by other requests is cleared out
@@ -440,7 +434,7 @@ export class App {
 				return this.#mergeResponses(response, originalResponse);
 			} catch {
 				// Middleware may be the cause of the error, so we try rendering 404/500.astro without it.
-				if (skipMiddleware === false && mod.onRequest) {
+				if (skipMiddleware === false) {
 					return this.#renderError(request, {
 						status,
 						response: originalResponse,

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

@@ -1,5 +1,6 @@
 import type {
 	Locales,
+	MiddlewareHandler,
 	RouteData,
 	SerializedRouteData,
 	SSRComponentMetadata,
@@ -54,6 +55,7 @@ export type SSRManifest = {
 	pageModule?: SinglePageBuiltModule;
 	pageMap?: Map<ComponentPath, ImportComponentInstance>;
 	i18n: SSRManifestI18n | undefined;
+	middleware: MiddlewareHandler;
 };
 
 export type SSRManifestI18n = {
@@ -65,7 +67,7 @@ export type SSRManifestI18n = {
 
 export type SerializedSSRManifest = Omit<
 	SSRManifest,
-	'routes' | 'assets' | 'componentMetadata' | 'clientDirectives'
+	'middleware' | 'routes' | 'assets' | 'componentMetadata' | 'clientDirectives'
 > & {
 	routes: SerializedRouteInfo[];
 	assets: string[];

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

@@ -8,6 +8,7 @@ import type {
 	AstroSettings,
 	ComponentInstance,
 	GetStaticPathsItem,
+	MiddlewareHandler,
 	RouteData,
 	RouteType,
 	SSRError,
@@ -145,10 +146,17 @@ export async function generatePages(opts: StaticBuildOptions, internals: BuildIn
 		const baseDirectory = getOutputDirectory(opts.settings.config);
 		const renderersEntryUrl = new URL('renderers.mjs', baseDirectory);
 		const renderers = await import(renderersEntryUrl.toString());
+		let middleware: MiddlewareHandler = (_, next) => next();
+		try {
+			// middleware.mjs is not emitted if there is no user middleware
+			// in which case the import fails with ERR_MODULE_NOT_FOUND, and we fall back to a no-op middleware
+			middleware = await import(new URL('middleware.mjs', baseDirectory).toString()).then(mod => mod.onRequest);
+		} catch {}
 		manifest = createBuildManifest(
 			opts.settings,
 			internals,
-			renderers.renderers as SSRLoadedRenderer[]
+			renderers.renderers as SSRLoadedRenderer[],
+			middleware
 		);
 	}
 	const pipeline = new BuildPipeline(opts, internals, manifest);
@@ -249,8 +257,9 @@ async function generatePage(
 	// prepare information we need
 	const logger = pipeline.getLogger();
 	const config = pipeline.getConfig();
+	const manifest = pipeline.getManifest();
 	const pageModulePromise = ssrEntry.page;
-	const onRequest = ssrEntry.onRequest;
+	const onRequest = manifest.middleware;
 	const pageInfo = getPageDataByComponent(pipeline.getInternals(), pageData.route.component);
 
 	// Calculate information of the page, like scripts, links and styles
@@ -263,19 +272,15 @@ async function generatePage(
 	const scripts = pageInfo?.hoistedScript ?? null;
 	// prepare the middleware
 	const i18nMiddleware = createI18nMiddleware(
-		pipeline.getManifest().i18n,
-		pipeline.getManifest().base,
-		pipeline.getManifest().trailingSlash,
-		pipeline.getManifest().buildFormat
+		manifest.i18n,
+		manifest.base,
+		manifest.trailingSlash,
+		manifest.buildFormat
 	);
 	if (config.i18n && i18nMiddleware) {
-		if (onRequest) {
-			pipeline.setMiddlewareFunction(sequence(i18nMiddleware, onRequest));
-		} else {
-			pipeline.setMiddlewareFunction(i18nMiddleware);
-		}
+		pipeline.setMiddlewareFunction(sequence(i18nMiddleware, onRequest));
 		pipeline.onBeforeRenderRoute(i18nPipelineHook);
-	} else if (onRequest) {
+	} else {
 		pipeline.setMiddlewareFunction(onRequest);
 	}
 	if (!pageModulePromise) {
@@ -629,10 +634,11 @@ function getPrettyRouteName(route: RouteData): string {
  * @param settings
  * @param renderers
  */
-export function createBuildManifest(
+function createBuildManifest(
 	settings: AstroSettings,
 	internals: BuildInternals,
-	renderers: SSRLoadedRenderer[]
+	renderers: SSRLoadedRenderer[],
+	middleware: MiddlewareHandler
 ): SSRManifest {
 	let i18nManifest: SSRManifestI18n | undefined = undefined;
 	if (settings.config.i18n) {
@@ -660,5 +666,6 @@ export function createBuildManifest(
 		componentMetadata: internals.componentMetadata,
 		i18n: i18nManifest,
 		buildFormat: settings.config.build.format,
+		middleware
 	};
 }

packages/astro/src/core/build/plugins/plugin-manifest.ts

@@ -42,22 +42,18 @@ function vitePluginManifest(options: StaticBuildOptions, internals: BuildInterna
 		},
 		async load(id) {
 			if (id === RESOLVED_SSR_MANIFEST_VIRTUAL_MODULE_ID) {
-				const imports = [];
-				const contents = [];
-				const exports = [];
-				imports.push(
+				const imports = [
 					`import { deserializeManifest as _deserializeManifest } from 'astro/app'`,
 					`import { _privateSetManifestDontUseThis } from 'astro:ssr-manifest'`
-				);
-
-				contents.push(`
-const manifest = _deserializeManifest('${manifestReplace}');
-_privateSetManifestDontUseThis(manifest);
-`);
-
-				exports.push('export { manifest }');
-
-				return `${imports.join('\n')}${contents.join('\n')}${exports.join('\n')}`;
+				];
+				const contents = [
+					`const manifest = _deserializeManifest('${manifestReplace}');`,
+					`_privateSetManifestDontUseThis(manifest);`
+				];
+				const exports = [
+					`export { manifest }`
+				];
+				return [...imports, ...contents, ...exports].join('\n');
 			}
 		},
 

packages/astro/src/core/build/plugins/plugin-pages.ts

@@ -1,12 +1,10 @@
 import { extname } from 'node:path';
 import type { Plugin as VitePlugin } from 'vite';
-import type { AstroSettings } from '../../../@types/astro.js';
 import { routeIsRedirect } from '../../redirects/index.js';
 import { addRollupInput } from '../add-rollup-input.js';
 import { eachPageFromAllPages, type BuildInternals } from '../internal.js';
 import type { AstroBuildPlugin } from '../plugin.js';
 import type { StaticBuildOptions } from '../types.js';
-import { MIDDLEWARE_MODULE_ID } from './plugin-middleware.js';
 import { RENDERERS_MODULE_ID } from './plugin-renderers.js';
 import { ASTRO_PAGE_EXTENSION_POST_PATTERN, getPathFromVirtualModulePageName } from './util.js';
 
@@ -37,7 +35,6 @@ export function getVirtualModulePageIdFromPath(path: string) {
 function vitePluginPages(opts: StaticBuildOptions, internals: BuildInternals): VitePlugin {
 	return {
 		name: '@astro/plugin-build-pages',
-
 		options(options) {
 			if (opts.settings.config.output === 'static') {
 				const inputs = new Set<string>();
@@ -52,13 +49,11 @@ function vitePluginPages(opts: StaticBuildOptions, internals: BuildInternals): V
 				return addRollupInput(options, Array.from(inputs));
 			}
 		},
-
 		resolveId(id) {
 			if (id.startsWith(ASTRO_PAGE_MODULE_ID)) {
 				return '\0' + id;
 			}
 		},
-
 		async load(id) {
 			if (id.startsWith(ASTRO_PAGE_RESOLVED_MODULE_ID)) {
 				const imports: string[] = [];
@@ -74,15 +69,6 @@ function vitePluginPages(opts: StaticBuildOptions, internals: BuildInternals): V
 						imports.push(`import { renderers } from "${RENDERERS_MODULE_ID}";`);
 						exports.push(`export { renderers };`);
 
-						// The middleware should not be imported by the pages
-						if (shouldBundleMiddleware(opts.settings)) {
-							const middlewareModule = await this.resolve(MIDDLEWARE_MODULE_ID);
-							if (middlewareModule) {
-								imports.push(`import { onRequest } from "${middlewareModule.id}";`);
-								exports.push(`export { onRequest };`);
-							}
-						}
-
 						return `${imports.join('\n')}${exports.join('\n')}`;
 					}
 				}
@@ -91,13 +77,6 @@ function vitePluginPages(opts: StaticBuildOptions, internals: BuildInternals): V
 	};
 }
 
-export function shouldBundleMiddleware(settings: AstroSettings) {
-	if (settings.adapter?.adapterFeatures?.edgeMiddleware === true) {
-		return false;
-	}
-	return true;
-}
-
 export function pluginPages(opts: StaticBuildOptions, internals: BuildInternals): AstroBuildPlugin {
 	return {
 		targets: ['server'],