feat: better adapter type (#15412)

* feat: better adapter type

* fix

* Discard changes to packages/integrations/cloudflare/src/index.ts

* Apply suggestion from @florian-lefebvre

* feedback

Author: florian-lefebvre

.changeset/dry-icons-nail.md

@@ -0,0 +1,5 @@
+---
+'astro': patch
+---
+
+Improves the `AstroAdapter` type and how legacy adapters are handled

packages/astro/dev-only.d.ts

@@ -66,9 +66,6 @@ declare module 'virtual:astro:adapter-entrypoint' {
 
 declare module 'virtual:astro:adapter-config' {
 	export const args: any;
-	export const exports: string[] | undefined;
-	export const adapterFeatures: any;
-	export const serverEntrypoint: string;
 }
 
 declare module 'virtual:astro:dev-css' {

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

@@ -4,16 +4,22 @@ import type { BuildInternals } from '../internal.js';
 import type { StaticBuildOptions } from '../types.js';
 import { ASTRO_VITE_ENVIRONMENT_NAMES } from '../../constants.js';
 
-const SSR_VIRTUAL_MODULE_ID = 'virtual:astro:legacy-ssr-entry';
-export const RESOLVED_SSR_VIRTUAL_MODULE_ID = '\0' + SSR_VIRTUAL_MODULE_ID;
+type LegacyAdapter = Extract<AstroAdapter, { entryType?: 'legacy-dynamic' }>;
+
+function isLegacyAdapter(adapter: AstroAdapter): adapter is LegacyAdapter {
+	return adapter.entryType === undefined || adapter.entryType === 'legacy-dynamic';
+}
+
+export const LEGACY_SSR_ENTRY_VIRTUAL_MODULE = 'virtual:astro:legacy-ssr-entry';
+export const RESOLVED_LEGACY_SSR_ENTRY_VIRTUAL_MODULE = '\0' + LEGACY_SSR_ENTRY_VIRTUAL_MODULE;
 
 const ADAPTER_VIRTUAL_MODULE_ID = 'virtual:astro:adapter-entrypoint';
 const RESOLVED_ADAPTER_VIRTUAL_MODULE_ID = '\0' + ADAPTER_VIRTUAL_MODULE_ID;
 
 const ADAPTER_CONFIG_VIRTUAL_MODULE_ID = 'virtual:astro:adapter-config';
 const RESOLVED_ADAPTER_CONFIG_VIRTUAL_MODULE_ID = '\0' + ADAPTER_CONFIG_VIRTUAL_MODULE_ID;
 
-function vitePluginAdapter(adapter: AstroAdapter): VitePlugin {
+function vitePluginAdapter(adapter: LegacyAdapter): VitePlugin {
 	return {
 		name: '@astrojs/vite-plugin-astro-adapter',
 		enforce: 'post',
@@ -49,7 +55,7 @@ export default _serverEntrypoint.default;`,
  * Makes adapter config (args, exports, features, entrypoint) available at runtime
  * so the adapter can access its own configuration during SSR.
  */
-function vitePluginAdapterConfig(adapter: AstroAdapter): VitePlugin {
+function vitePluginAdapterConfig(adapter: LegacyAdapter): VitePlugin {
 	return {
 		name: '@astrojs/vite-plugin-astro-adapter-config',
 		enforce: 'post',
@@ -70,17 +76,14 @@ function vitePluginAdapterConfig(adapter: AstroAdapter): VitePlugin {
 			},
 			handler() {
 				return {
-					code: `export const args = ${adapter.args ? JSON.stringify(adapter.args, null, 2) : 'undefined'};
-export const exports = ${adapter.exports ? JSON.stringify(adapter.exports) : 'undefined'};
-export const adapterFeatures = ${adapter.adapterFeatures ? JSON.stringify(adapter.adapterFeatures, null, 2) : 'undefined'};
-export const serverEntrypoint = ${JSON.stringify(adapter.serverEntrypoint)};`,
+					code: `export const args = ${adapter.args ? JSON.stringify(adapter.args, null, 2) : 'undefined'};`,
 				};
 			},
 		},
 	};
 }
 
-function vitePluginSSR(internals: BuildInternals, adapter: AstroAdapter): VitePlugin {
+function vitePluginSSR(internals: BuildInternals, adapter: LegacyAdapter): VitePlugin {
 	return {
 		name: '@astrojs/vite-plugin-astro-ssr-server',
 		enforce: 'post',
@@ -89,15 +92,15 @@ function vitePluginSSR(internals: BuildInternals, adapter: AstroAdapter): VitePl
 		},
 		resolveId: {
 			filter: {
-				id: new RegExp(`^${SSR_VIRTUAL_MODULE_ID}$`),
+				id: new RegExp(`^${LEGACY_SSR_ENTRY_VIRTUAL_MODULE}$`),
 			},
 			handler() {
-				return RESOLVED_SSR_VIRTUAL_MODULE_ID;
+				return RESOLVED_LEGACY_SSR_ENTRY_VIRTUAL_MODULE;
 			},
 		},
 		load: {
 			filter: {
-				id: new RegExp(`^${RESOLVED_SSR_VIRTUAL_MODULE_ID}$`),
+				id: new RegExp(`^${RESOLVED_LEGACY_SSR_ENTRY_VIRTUAL_MODULE}$`),
 			},
 			handler() {
 				const exports: string[] = [];
@@ -131,14 +134,17 @@ function vitePluginSSR(internals: BuildInternals, adapter: AstroAdapter): VitePl
 }
 
 export function pluginSSR(options: StaticBuildOptions, internals: BuildInternals): VitePlugin[] {
-	// We check before this point if there's an adapter, so we can safely assume it exists here.
-	const adapter = options.settings.adapter!;
+	const adapter = options.settings.adapter;
 	const ssr = options.settings.buildOutput === 'server';
 
-	const plugins: VitePlugin[] = [vitePluginAdapter(adapter), vitePluginAdapterConfig(adapter)];
+	const plugins: VitePlugin[] = [];
+
+	if (adapter && isLegacyAdapter(adapter)) {
+		plugins.push(vitePluginAdapter(adapter), vitePluginAdapterConfig(adapter));
 
-	if (ssr) {
-		plugins.unshift(vitePluginSSR(internals, adapter));
+		if (ssr) {
+			plugins.unshift(vitePluginSSR(internals, adapter));
+		}
 	}
 
 	return plugins;

packages/astro/src/core/build/static-build.ts

@@ -22,7 +22,7 @@ import { generatePages } from './generate.js';
 import { trackPageData } from './internal.js';
 import { getAllBuildPlugins } from './plugins/index.js';
 import { manifestBuildPostHook } from './plugins/plugin-manifest.js';
-import { RESOLVED_SSR_VIRTUAL_MODULE_ID } from './plugins/plugin-ssr.js';
+import { LEGACY_SSR_ENTRY_VIRTUAL_MODULE, RESOLVED_LEGACY_SSR_ENTRY_VIRTUAL_MODULE } from './plugins/plugin-ssr.js';
 import { ASTRO_PAGE_EXTENSION_POST_PATTERN } from './plugins/util.js';
 import type { StaticBuildOptions } from './types.js';
 import { encodeName, getTimeStat, viteBuildReturnToRollupOutputs } from './util.js';
@@ -228,7 +228,7 @@ async function buildEnvironments(opts: StaticBuildOptions, internals: BuildInter
 				...viteConfig.build?.rollupOptions,
 				// Setting as `exports-only` allows us to safely delete inputs that are only used during prerendering
 				preserveEntrySignatures: 'exports-only',
-				...(useLegacyDynamic ? { input: 'virtual:astro:legacy-ssr-entry' } : {}),
+				...(useLegacyDynamic ? { input: LEGACY_SSR_ENTRY_VIRTUAL_MODULE } : {}),
 				output: {
 					hoistTransitiveImports: false,
 					format: 'esm',
@@ -264,7 +264,7 @@ async function buildEnvironments(opts: StaticBuildOptions, internals: BuildInter
 								routes,
 							);
 						} else if (
-							chunkInfo.facadeModuleId === RESOLVED_SSR_VIRTUAL_MODULE_ID ||
+							chunkInfo.facadeModuleId === RESOLVED_LEGACY_SSR_ENTRY_VIRTUAL_MODULE ||
 							// This catches the case when the adapter uses `entryType: 'self'. When doing so,
 							// the adapter must set rollupOptions.input.
 							isRollupInput(chunkInfo.name) ||

packages/astro/src/types/public/integrations.ts

@@ -119,20 +119,33 @@ export interface AstroAdapterClientConfig {
 	assetQueryParams?: URLSearchParams;
 }
 
-export interface AstroAdapter {
-	name: string;
+interface AdapterLegacyDynamicProperties {
+	/**
+	 * Determines how the adapter's entrypoint is handled during the build.
+	 * - `'self'`: The adapter defines its own entrypoint and sets rollupOptions.input
+	 * - `'legacy-dynamic'`: Uses the virtual module entrypoint with dynamic exports
+	 * @default 'legacy-dynamic'
+	 */
+	entryType?: 'legacy-dynamic';
 	serverEntrypoint?: string | URL;
-	previewEntrypoint?: string | URL;
 	exports?: string[];
 	args?: any;
-	adapterFeatures?: AstroAdapterFeatures;
+}
+
+interface AdapterSelfProperties {
 	/**
 	 * Determines how the adapter's entrypoint is handled during the build.
 	 * - `'self'`: The adapter defines its own entrypoint and sets rollupOptions.input
 	 * - `'legacy-dynamic'`: Uses the virtual module entrypoint with dynamic exports
 	 * @default 'legacy-dynamic'
 	 */
-	entryType?: 'self' | 'legacy-dynamic';
+	entryType: 'self';
+}
+
+export type AstroAdapter = {
+	name: string;
+	previewEntrypoint?: string | URL;
+	adapterFeatures?: AstroAdapterFeatures;
 	/**
 	 * List of features supported by an adapter.
 	 *
@@ -143,7 +156,7 @@ export interface AstroAdapter {
 	 * Configuration for Astro's client-side code.
 	 */
 	client?: AstroAdapterClientConfig;
-}
+} & (AdapterLegacyDynamicProperties | AdapterSelfProperties);
 
 export type AstroAdapterFeatureMap = {
 	/**