feat(i18n): domain with lookup table

packages/astro/src/@types/astro.ts

@@ -1520,7 +1520,7 @@ export interface AstroUserConfig {
 			 * @docs
 			 * @kind h4
 			 * @name experimental.i18n.routingStrategy
-			 * @type {'prefix-always' | 'prefix-other-locales'}
+			 * @type {'prefix-always' | 'prefix-other-locales' | 'domain'}
 			 * @default 'prefix-other-locales'
 			 * @version 3.5.0
 			 * @description
@@ -1533,9 +1533,12 @@ export interface AstroUserConfig {
 			 *  - `prefix-always`: All URLs will display a language prefix.
 			 *    URLs will be of the form `example.com/[locale]/content/` for every route, including the default language.
 			 *    Localized folders are used for every language, including the default.
+			 *  - `domain`: SSR only, it enables support for different domains. When a locale is mapped to domain, all the URLs won't have the language prefix.
+			 *    You map `fr` to `fr.example.com`, if you want a to have a blog page to look like `fr.example.com/blog` instead of `example.com/fr/blog`.
+			 *    The localised folders be must in the `src/pages/` folder.
 			 *
 			 */
-			routingStrategy?: 'prefix-always' | 'prefix-other-locales';
+			routingStrategy?: 'prefix-always' | 'prefix-other-locales' | 'domain';
 
 			/**
 			 * @docs
@@ -1556,7 +1559,8 @@ export interface AstroUserConfig {
 			 *            locales: ["en", "fr", "pt-br", "es"],
 			 *            domains: {
 			 *                fr: "https://fr.example.com",
-			 *            }
+			 *            },
+			 *            routingStrategy: "domain"
 			 *        }
 			 *    }
 			 * })

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

@@ -131,8 +131,29 @@ export class App {
 		const url = new URL(request.url);
 		// ignore requests matching public assets
 		if (this.#manifest.assets.has(url.pathname)) return undefined;
-		const pathname = prependForwardSlash(this.removeBase(url.pathname));
-		const routeData = matchRoute(pathname, this.#manifestData);
+		let pathname;
+		if (this.#manifest.i18n && this.#manifest.i18n.routingStrategy === 'domain') {
+			const host = request.headers.get('X-Forwarded-Host');
+			if (host) {
+				try {
+					let hostUrl = new URL(this.removeBase(url.pathname), host);
+					const maybePathname = this.#manifest.i18n.domainLookupTable[hostUrl.toString()];
+					if (maybePathname) {
+						pathname = maybePathname;
+					}
+				} catch (e) {
+					// waiting to decide what to do here
+					// eslint-disable-next-line no-console
+					console.error(e);
+					// TODO: What kind of error should we try? This happens if we have an invalid value inside the X-Forwarded-Host header
+				}
+			}
+		}
+		if (!pathname) {
+			pathname = prependForwardSlash(this.removeBase(url.pathname));
+		}
+		let routeData = matchRoute(pathname, this.#manifestData);
+
 		// missing routes fall-through, prerendered are handled by static layer
 		if (!routeData || routeData.prerender) return undefined;
 		return routeData;

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

@@ -55,9 +55,10 @@ export type SSRManifest = {
 
 export type SSRManifestI18n = {
 	fallback?: Record<string, string>;
-	routingStrategy?: 'prefix-always' | 'prefix-other-locales';
+	routingStrategy?: 'prefix-always' | 'prefix-other-locales' | 'domain';
 	locales: string[];
 	defaultLocale: string;
+	domainLookupTable: Record<string, string>;
 };
 
 export type SerializedSSRManifest = Omit<

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

@@ -634,6 +634,7 @@ export function createBuildManifest(
 			routingStrategy: settings.config.experimental.i18n.routingStrategy,
 			defaultLocale: settings.config.experimental.i18n.defaultLocale,
 			locales: settings.config.experimental.i18n.locales,
+			domainLookupTable: {},
 		};
 	}
 	return {

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

@@ -9,13 +9,14 @@ import type {
 	SerializedRouteInfo,
 	SerializedSSRManifest,
 } from '../../app/types.js';
-import { joinPaths, prependForwardSlash } from '../../path.js';
+import { appendForwardSlash, joinPaths, prependForwardSlash } from '../../path.js';
 import { serializeRouteData } from '../../routing/index.js';
 import { addRollupInput } from '../add-rollup-input.js';
 import { getOutFile, getOutFolder } from '../common.js';
 import { cssOrder, mergeInlineCss, type BuildInternals } from '../internal.js';
 import type { AstroBuildPlugin } from '../plugin.js';
 import type { StaticBuildOptions } from '../types.js';
+import { shouldAppendForwardSlash } from '../util.js';
 
 const manifestReplace = '@@ASTRO_MANIFEST_REPLACE@@';
 const replaceExp = new RegExp(`['"](${manifestReplace})['"]`, 'g');
@@ -161,6 +162,7 @@ function buildManifest(
 	const { settings } = opts;
 
 	const routes: SerializedRouteInfo[] = [];
+	const domainLookupTable: Record<string, string> = {};
 	const entryModules = Object.fromEntries(internals.entrySpecifierToBundleMap.entries());
 	if (settings.scripts.some((script) => script.stage === 'page')) {
 		staticFiles.push(entryModules[PAGE_SCRIPT_ID]);
@@ -234,6 +236,32 @@ function buildManifest(
 			styles,
 			routeData: serializeRouteData(route, settings.config.trailingSlash),
 		});
+
+		/**
+		 * logic meant for i18n domain support, where we fill the lookup table
+		 */
+		const i18n = settings.config.experimental.i18n;
+		if (i18n && i18n.domains && i18n.routingStrategy === 'domain') {
+			// Domain routing strategy assumes that the locale starts at the beginning of the path, so it's safe to get the first item
+			// This is something like /es/guides/getting-started
+			const segments = route.route.split('/');
+			const pathnameLocale = segments[1];
+			const maybeLocaleDomain = i18n.domains[pathnameLocale];
+			if (maybeLocaleDomain) {
+				// This is something like guides/getting-started
+				let pathnameWithoutLocale = segments
+					.filter((segment) => segment !== pathnameLocale)
+					.slice(1)
+					.join('/');
+				if (shouldAppendForwardSlash(settings.config.trailingSlash, settings.config.build.format)) {
+					pathnameWithoutLocale = appendForwardSlash(pathnameWithoutLocale);
+				}
+				// We build a URL object like this: https://es.example.com/guides/getting-started
+				const domainPath = new URL(pathnameWithoutLocale, maybeLocaleDomain);
+				// We map  https://es.example.com/guides/getting-started -> /es/guides/getting-started
+				domainLookupTable[domainPath.toString()] = route.route;
+			}
+		}
 	}
 
 	// HACK! Patch this special one.
@@ -248,6 +276,7 @@ function buildManifest(
 			routingStrategy: settings.config.experimental.i18n.routingStrategy,
 			locales: settings.config.experimental.i18n.locales,
 			defaultLocale: settings.config.experimental.i18n.defaultLocale,
+			domainLookupTable,
 		};
 	}
 

packages/astro/src/core/config/schema.ts

@@ -356,16 +356,15 @@ export const AstroConfigSchema = z.object({
 									)
 							)
 							.optional(),
-						// TODO: properly add default when the feature goes of experimental
 						routingStrategy: z
-							.enum(['prefix-always', 'prefix-other-locales'])
+							.enum(['prefix-always', 'prefix-other-locales', 'domain'])
 							.optional()
 							.default('prefix-other-locales'),
 					})
 					.optional()
 					.superRefine((i18n, ctx) => {
 						if (i18n) {
-							const { defaultLocale, locales, fallback, domains } = i18n;
+							const { defaultLocale, locales, fallback, domains, routingStrategy } = i18n;
 							if (!locales.includes(defaultLocale)) {
 								ctx.addIssue({
 									code: z.ZodIssueCode.custom,
@@ -397,6 +396,16 @@ export const AstroConfigSchema = z.object({
 								}
 							}
 							if (domains) {
+								const entries = Object.entries(domains);
+								if (entries.length > 0) {
+									if (routingStrategy !== 'domain') {
+										ctx.addIssue({
+											code: z.ZodIssueCode.custom,
+											message: `When specifying some domains, the property \`i18n.routingStrategy\` must be set to \`"domain"\`.`,
+										});
+									}
+								}
+
 								for (const [domainKey, domainValue] of Object.entries(domains)) {
 									if (!locales.includes(domainKey)) {
 										ctx.addIssue({

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

@@ -93,6 +93,7 @@ export function createDevelopmentManifest(settings: AstroSettings): SSRManifest
 			routingStrategy: settings.config.experimental.i18n.routingStrategy,
 			defaultLocale: settings.config.experimental.i18n.defaultLocale,
 			locales: settings.config.experimental.i18n.locales,
+			domainLookupTable: {},
 		};
 	}
 	return {

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

@@ -277,11 +277,7 @@ export async function handleRoute({
 
 	const onRequest = middleware?.onRequest as MiddlewareEndpointHandler | undefined;
 	if (config.experimental.i18n) {
-		const i18Middleware = createI18nMiddleware(
-			config.experimental.i18n,
-			config.base,
-			config.trailingSlash
-		);
+		const i18Middleware = createI18nMiddleware(manifest.i18n, config.base, config.trailingSlash);
 
 		if (i18Middleware) {
 			if (onRequest) {

packages/astro/test/fixtures/i18n-routing-subdomain/astro.config.mjs

@@ -0,0 +1,19 @@
+import { defineConfig} from "astro/config";
+
+export default defineConfig({
+	trailingSlash: "never",
+	experimental: {
+		i18n: {
+			defaultLocale: 'en',
+			locales: [
+				'en', 'pt', 'it'
+			],
+			domains: {
+				pt: "https://example.pt"
+			},
+			routingStrategy: "domain"
+		},
+
+	},
+	base: "/new-site"
+})

packages/astro/test/fixtures/i18n-routing-subdomain/package.json

@@ -0,0 +1,8 @@
+{
+  "name": "@test/i18n-routing-subdomain",
+  "version": "0.0.0",
+  "private": true,
+  "dependencies": {
+    "astro": "workspace:*"
+  }
+}

packages/astro/test/fixtures/i18n-routing-subdomain/src/pages/en/blog/[id].astro

@@ -0,0 +1,18 @@
+---
+export function getStaticPaths() {
+    return [
+        {params: {id: '1'}, props: { content: "Hello world" }},
+        {params: {id: '2'}, props: { content: "Eat Something" }},
+        {params: {id: '3'}, props: { content: "How are you?" }},
+    ];
+}
+const { content } = Astro.props;
+---
+<html>
+<head>
+    <title>Astro</title>
+</head>
+<body>
+{content}
+</body>
+</html>

packages/astro/test/fixtures/i18n-routing-subdomain/src/pages/en/index.astro

@@ -0,0 +1,8 @@
+<html>
+<head>
+    <title>Astro</title>
+</head>
+<body>
+Hello
+</body>
+</html>

packages/astro/test/fixtures/i18n-routing-subdomain/src/pages/en/start.astro

@@ -0,0 +1,8 @@
+<html>
+<head>
+	<title>Astro</title>
+</head>
+<body>
+Start
+</body>
+</html>

packages/astro/test/fixtures/i18n-routing-subdomain/src/pages/pt/blog/[id].astro

@@ -0,0 +1,18 @@
+---
+export function getStaticPaths() {
+    return [
+        {params: {id: '1'}, props: { content: "Hola mundo" }},
+        {params: {id: '2'}, props: { content: "Eat Something" }},
+        {params: {id: '3'}, props: { content: "How are you?" }},
+    ];
+}
+const { content } = Astro.props;
+---
+<html>
+<head>
+    <title>Astro</title>
+</head>
+<body>
+{content}
+</body>
+</html>

packages/astro/test/fixtures/i18n-routing-subdomain/src/pages/pt/start.astro

@@ -0,0 +1,8 @@
+<html>
+<head>
+	<title>Astro</title>
+</head>
+<body>
+Oi essa e start
+</body>
+</html>

packages/astro/test/i18-routing.test.js

@@ -1009,4 +1009,30 @@ describe('[SSR] i18n routing', () => {
 			});
 		});
 	});
+
+	describe('i18n routing with routing strategy [subdomain]', () => {
+		/** @type {import('./test-utils').Fixture} */
+		let fixture;
+
+		before(async () => {
+			fixture = await loadFixture({
+				root: './fixtures/i18n-routing-subdomain/',
+				output: 'server',
+				adapter: testAdapter(),
+			});
+			await fixture.build();
+			app = await fixture.loadTestAdapterApp();
+		});
+
+		it('should render the en locale', async () => {
+			let request = new Request('http://example.pt/new-site/start', {
+				headers: {
+					'X-Forwarded-Host': 'https://example.pt',
+				},
+			});
+			let response = await app.render(request);
+			expect(response.status).to.equal(200);
+			expect(await response.text()).includes('Oi essa e start\n');
+		});
+	});
 });

packages/astro/test/units/config/config-validate.test.js

@@ -191,6 +191,7 @@ describe('Config Validation', () => {
 							domains: {
 								en: 'www.example.com',
 							},
+							routingStrategy: 'domain',
 						},
 					},
 				},
@@ -212,6 +213,7 @@ describe('Config Validation', () => {
 							domains: {
 								en: 'https://www.example.com/blog/page/',
 							},
+							routingStrategy: 'domain',
 						},
 					},
 				},
@@ -222,5 +224,26 @@ describe('Config Validation', () => {
 				"The URL `https://www.example.com/blog/page/` must contain only the origin. A subsequent pathname isn't allowed here. Remove `/blog/page/`."
 			);
 		});
+
+		it('errors if there are domains, and the routing strategy is not correct', async () => {
+			const configError = await validateConfig(
+				{
+					experimental: {
+						i18n: {
+							defaultLocale: 'en',
+							locales: ['es', 'en'],
+							domains: {
+								en: 'https://www.example.com/',
+							},
+						},
+					},
+				},
+				process.cwd()
+			).catch((err) => err);
+			expect(configError instanceof z.ZodError).to.equal(true);
+			expect(configError.errors[0].message).to.equal(
+				'When specifying some domains, the property `i18n.routingStrategy` must be set to `"domain"`.'
+			);
+		});
 	});
 });