[Fix] Add prerendered assets to Vercel config (#8332)

* Add prerendered assets to Vercel config

* use adapter-vercel logic inside adapter-static

* simplify

* update changeset

* add adapter-vercel changeset

Co-authored-by: Rich Harris <[email protected]>

Author: pawelblaszczyk5

.changeset/healthy-singers-stare.md

@@ -0,0 +1,5 @@
+---
+'@sveltejs/adapter-vercel': patch
+---
+
+[fix] only apply immutable cache-control headers to immutable assets

.changeset/old-chicken-cough.md

@@ -0,0 +1,5 @@
+---
+'@sveltejs/adapter-static': patch
+---
+
+[fix] match `adapter-vercel` logic for serving prerendered content

packages/adapter-static/index.js

@@ -71,9 +71,7 @@ See https://kit.svelte.dev/docs/page-options#prerender for more details`
 				assets = pages,
 				fallback,
 				precompress
-			} = options ??
-			platform?.defaults(builder.config) ??
-			/** @type {import('./index').AdapterOptions} */ ({});
+			} = options ?? platform?.defaults ?? /** @type {import('./index').AdapterOptions} */ ({});
 
 			builder.rimraf(assets);
 			builder.rimraf(pages);

packages/adapter-static/platforms.js

@@ -4,26 +4,22 @@ import fs from 'fs';
  * @typedef {{
  *   name: string;
  *   test: () => boolean;
- *   defaults: (config: any) => import('./index').AdapterOptions; // TODO
+ *   defaults: import('./index').AdapterOptions;
  *   done: (builder: import('@sveltejs/kit').Builder) => void;
  * }}
  * Platform */
 
+// This function is duplicated in adapter-vercel
 /** @param {import('@sveltejs/kit').Builder} builder */
-function vercel_routes(builder) {
+function static_vercel_config(builder) {
 	/** @type {any[]} */
-	const routes = [
-		{
-			src: `/${builder.config.kit.appDir}/immutable/.+`,
-			headers: {
-				'cache-control': 'public, immutable, max-age=31536000'
-			}
-		}
-	];
+	const prerendered_redirects = [];
+
+	/** @type {Record<string, { path: string }>} */
+	const overrides = {};
 
-	// explicit redirects
 	for (const [src, redirect] of builder.prerendered.redirects) {
-		routes.push({
+		prerendered_redirects.push({
 			src,
 			headers: {
 				Location: redirect.location
@@ -32,51 +28,48 @@ function vercel_routes(builder) {
 		});
 	}
 
-	// prerendered pages
-	for (const [src, page] of builder.prerendered.pages) {
-		routes.push({
-			src,
-			dest: `${builder.config.kit.appDir}/prerendered/${page.file}`
-		});
-	}
+	for (const [path, page] of builder.prerendered.pages) {
+		if (path.endsWith('/') && path !== '/') {
+			prerendered_redirects.push(
+				{ src: path, dest: path.slice(0, -1) },
+				{ src: path.slice(0, -1), status: 308, headers: { Location: path } }
+			);
 
-	// implicit redirects (trailing slashes)
-	for (const [src] of builder.prerendered.pages) {
-		if (src !== '/') {
-			routes.push({
-				src: src.endsWith('/') ? src.slice(0, -1) : src + '/',
-				headers: {
-					location: src
-				},
-				status: 308
-			});
+			overrides[page.file] = { path: path.slice(1, -1) };
+		} else {
+			overrides[page.file] = { path: path.slice(1) };
 		}
 	}
 
-	routes.push({
-		handle: 'filesystem'
-	});
-
-	return routes;
+	return {
+		version: 3,
+		routes: [
+			...prerendered_redirects,
+			{
+				src: `/${builder.getAppPath()}/immutable/.+`,
+				headers: {
+					'cache-control': 'public, immutable, max-age=31536000'
+				}
+			},
+			{
+				handle: 'filesystem'
+			}
+		],
+		overrides
+	};
 }
 
 /** @type {Platform[]} */
 export const platforms = [
 	{
 		name: 'Vercel',
 		test: () => !!process.env.VERCEL,
-		defaults: (config) => ({
-			pages: `.vercel/output/static/${config.kit.appDir}/prerendered`,
-			assets: '.vercel/output/static'
-		}),
+		defaults: {
+			pages: '.vercel/output/static'
+		},
 		done: (builder) => {
-			fs.writeFileSync(
-				'.vercel/output/config.json',
-				JSON.stringify({
-					version: 3,
-					routes: vercel_routes(builder)
-				})
-			);
+			const config = static_vercel_config(builder);
+			fs.writeFileSync('.vercel/output/config.json', JSON.stringify(config, null, '  '));
 		}
 	}
 ];

packages/adapter-vercel/index.js

@@ -25,48 +25,7 @@ const plugin = function ({ external = [], edge, split } = {}) {
 				functions: `${dir}/functions`
 			};
 
-			/** @type {any[]} */
-			const prerendered_redirects = [];
-
-			/** @type {Record<string, { path: string }>} */
-			const overrides = {};
-
-			for (const [src, redirect] of builder.prerendered.redirects) {
-				prerendered_redirects.push({
-					src,
-					headers: {
-						Location: redirect.location
-					},
-					status: redirect.status
-				});
-			}
-
-			for (const [path, page] of builder.prerendered.pages) {
-				if (path.endsWith('/') && path !== '/') {
-					prerendered_redirects.push(
-						{ src: path, dest: path.slice(0, -1) },
-						{ src: path.slice(0, -1), status: 308, headers: { Location: path } }
-					);
-
-					overrides[page.file] = { path: path.slice(1, -1) };
-				} else {
-					overrides[page.file] = { path: path.slice(1) };
-				}
-			}
-
-			/** @type {any[]} */
-			const routes = [
-				...prerendered_redirects,
-				{
-					src: `/${builder.getAppPath()}/.+`,
-					headers: {
-						'cache-control': 'public, immutable, max-age=31536000'
-					}
-				},
-				{
-					handle: 'filesystem'
-				}
-			];
+			const config = static_vercel_config(builder);
 
 			builder.log.minor('Generating serverless function...');
 
@@ -97,7 +56,7 @@ const plugin = function ({ external = [], edge, split } = {}) {
 					`nodejs${node_version.major}.x`
 				);
 
-				routes.push({ src: pattern, dest: `/${name}` });
+				config.routes.push({ src: pattern, dest: `/${name}` });
 			}
 
 			/**
@@ -142,7 +101,7 @@ const plugin = function ({ external = [], edge, split } = {}) {
 					})
 				);
 
-				routes.push({ src: pattern, dest: `/${name}` });
+				config.routes.push({ src: pattern, dest: `/${name}` });
 			}
 
 			const generate_function = edge ? generate_edge_function : generate_serverless_function;
@@ -182,18 +141,7 @@ const plugin = function ({ external = [], edge, split } = {}) {
 
 			builder.log.minor('Writing routes...');
 
-			write(
-				`${dir}/config.json`,
-				JSON.stringify(
-					{
-						version: 3,
-						routes,
-						overrides
-					},
-					null,
-					'  '
-				)
-			);
+			write(`${dir}/config.json`, JSON.stringify(config, null, '  '));
 		}
 	};
 };
@@ -225,6 +173,56 @@ function get_node_version() {
 	return { major, full };
 }
 
+// This function is duplicated in adapter-static
+/** @param {import('@sveltejs/kit').Builder} builder */
+function static_vercel_config(builder) {
+	/** @type {any[]} */
+	const prerendered_redirects = [];
+
+	/** @type {Record<string, { path: string }>} */
+	const overrides = {};
+
+	for (const [src, redirect] of builder.prerendered.redirects) {
+		prerendered_redirects.push({
+			src,
+			headers: {
+				Location: redirect.location
+			},
+			status: redirect.status
+		});
+	}
+
+	for (const [path, page] of builder.prerendered.pages) {
+		if (path.endsWith('/') && path !== '/') {
+			prerendered_redirects.push(
+				{ src: path, dest: path.slice(0, -1) },
+				{ src: path.slice(0, -1), status: 308, headers: { Location: path } }
+			);
+
+			overrides[page.file] = { path: path.slice(1, -1) };
+		} else {
+			overrides[page.file] = { path: path.slice(1) };
+		}
+	}
+
+	return {
+		version: 3,
+		routes: [
+			...prerendered_redirects,
+			{
+				src: `/${builder.getAppPath()}/immutable/.+`,
+				headers: {
+					'cache-control': 'public, immutable, max-age=31536000'
+				}
+			},
+			{
+				handle: 'filesystem'
+			}
+		],
+		overrides
+	};
+}
+
 /**
  * @param {import('@sveltejs/kit').Builder} builder
  * @param {string} entry