feat(vercel): `includeFiles` and `excludeFiles` (#5085)

* refactor + include/excludeFiles

* Changeset

* Updated README.md

Co-authored-by: Sarah Rainsberger <sarah@rainsberger.ca>

* Missing .js

Co-authored-by: Sarah Rainsberger <sarah@rainsberger.ca>

6 files changed, 168 insertions, 60 deletions

diff --git a/.changeset/violet-buckets-call.md b/.changeset/violet-buckets-call.md
new file mode 100644
index 000000000..37688d16b
--- /dev/null
+++ b/.changeset/violet-buckets-call.md
@@ -0,0 +1,5 @@
+---
+'@astrojs/vercel': minor
+---
+
+Added `includeFiles` and `excludeFiles` options
diff --git a/packages/integrations/vercel/README.md b/packages/integrations/vercel/README.md
index 532cf3141..ca9610a61 100644
--- a/packages/integrations/vercel/README.md
+++ b/packages/integrations/vercel/README.md
@@ -84,7 +84,49 @@ vercel deploy --prebuilt
 
 ## Configuration
 
-This adapter does not expose any configuration options.
+To configure this adapter, pass an object to the `vercel()` function call in `astro.config.mjs`:
+
+### includeFiles
+
+> **Type:** `string[]`
+> **Available for:** Edge, Serverless
+
+Use this property to force files to be bundled with your function. This is helpful when you notice missing files.
+
+```js
+import { defineConfig } from 'astro/config';
+import vercel from '@astrojs/vercel/serverless';
+
+export default defineConfig({
+  output: 'server',
+  adapter: vercel({
+    includeFiles: ['./my-data.json']
+  })
+});
+```
+
+> **Note**
+> When building for the Edge, all the depencies get bundled in a single file to save space. **No extra file will be bundled**. So, if you _need_ some file inside the function, you have to specify it in `includeFiles`.
+
+
+### excludeFiles
+
+> **Type:** `string[]`
+> **Available for:** Serverless
+
+Use this property to exclude any files from the bundling process that would otherwise be included.
+
+```js
+import { defineConfig } from 'astro/config';
+import vercel from '@astrojs/vercel/serverless';
+
+export default defineConfig({
+  output: 'server',
+  adapter: vercel({
+    excludeFiles: ['./src/some_big_file.jpg']
+  })
+});
+```
 
 ## Troubleshooting
 
diff --git a/packages/integrations/vercel/src/edge/adapter.ts b/packages/integrations/vercel/src/edge/adapter.ts
index c842cb38f..73cc89483 100644
--- a/packages/integrations/vercel/src/edge/adapter.ts
+++ b/packages/integrations/vercel/src/edge/adapter.ts
@@ -1,6 +1,8 @@
 import type { AstroAdapter, AstroConfig, AstroIntegration } from 'astro';
+import { relative as relativePath } from 'node:path';
+import { fileURLToPath } from 'node:url';
 
-import { getVercelOutput, writeJson } from '../lib/fs.js';
+import { getVercelOutput, removeDir, writeJson, copyFilesToFunction } from '../lib/fs.js';
 import { getRedirects } from '../lib/redirects.js';
 
 const PACKAGE_NAME = '@astrojs/vercel/edge';
@@ -13,8 +15,13 @@ function getAdapter(): AstroAdapter {
 	};
 }
 
-export default function vercelEdge(): AstroIntegration {
+export interface VercelEdgeConfig {
+	includeFiles?: string[];
+}
+
+export default function vercelEdge({ includeFiles = [] }: VercelEdgeConfig = {}): AstroIntegration {
 	let _config: AstroConfig;
+	let buildTempFolder: URL;
 	let functionFolder: URL;
 	let serverEntry: string;
 	let needsBuildConfig = false;
@@ -30,13 +37,15 @@ export default function vercelEdge(): AstroIntegration {
 					build: {
 						serverEntry: 'entry.mjs',
 						client: new URL('./static/', outDir),
-						server: new URL('./functions/render.func/', config.outDir),
+						server: new URL('./dist/', config.root),
 					},
 				});
 			},
 			'astro:config:done': ({ setAdapter, config }) => {
 				setAdapter(getAdapter());
 				_config = config;
+				buildTempFolder = config.build.server;
+				functionFolder = new URL('./functions/render.func/', config.outDir);
 				serverEntry = config.build.serverEntry;
 				functionFolder = config.build.server;
 
@@ -50,8 +59,8 @@ export default function vercelEdge(): AstroIntegration {
 			'astro:build:start': ({ buildConfig }) => {
 				if (needsBuildConfig) {
 					buildConfig.client = new URL('./static/', _config.outDir);
+					buildTempFolder = buildConfig.server = new URL('./dist/', _config.root);
 					serverEntry = buildConfig.serverEntry = 'entry.mjs';
-					functionFolder = buildConfig.server = new URL('./functions/render.func/', _config.outDir);
 				}
 			},
 			'astro:build:setup': ({ vite, target }) => {
@@ -79,11 +88,25 @@ export default function vercelEdge(): AstroIntegration {
 				}
 			},
 			'astro:build:done': async ({ routes }) => {
+				const entry = new URL(serverEntry, buildTempFolder);
+
+				// Copy entry and other server files
+				const commonAncestor = await copyFilesToFunction(
+					[
+						new URL(serverEntry, buildTempFolder),
+						...includeFiles.map((file) => new URL(file, _config.root)),
+					],
+					functionFolder
+				);
+
+				// Remove temporary folder
+				await removeDir(buildTempFolder);
+
 				// Edge function config
 				// https://vercel.com/docs/build-output-api/v3#vercel-primitives/edge-functions/configuration
 				await writeJson(new URL(`./.vc-config.json`, functionFolder), {
 					runtime: 'edge',
-					entrypoint: serverEntry,
+					entrypoint: relativePath(commonAncestor, fileURLToPath(entry)),
 				});
 
 				// Output configuration
diff --git a/packages/integrations/vercel/src/lib/fs.ts b/packages/integrations/vercel/src/lib/fs.ts
index 64c4c69ba..47b218ce5 100644
--- a/packages/integrations/vercel/src/lib/fs.ts
+++ b/packages/integrations/vercel/src/lib/fs.ts
@@ -1,5 +1,7 @@
 import type { PathLike } from 'node:fs';
 import * as fs from 'node:fs/promises';
+import nodePath from 'node:path';
+import { fileURLToPath } from 'node:url';
 
 export async function writeJson<T>(path: PathLike, data: T) {
 	await fs.writeFile(path, JSON.stringify(data), { encoding: 'utf-8' });
@@ -15,3 +17,58 @@ export async function emptyDir(dir: PathLike): Promise<void> {
 }
 
 export const getVercelOutput = (root: URL) => new URL('./.vercel/output/', root);
+
+/**
+ * Copies files into a folder keeping the folder structure intact.
+ * The resulting file tree will start at the common ancestor.
+ *
+ * @param {URL[]} files A list of files to copy (absolute path).
+ * @param {URL} outDir Destination folder where to copy the files to (absolute path).
+ * @param {URL[]} [exclude] A list of files to exclude (absolute path).
+ * @returns {Promise<string>} The common ancestor of the copied files.
+ */
+export async function copyFilesToFunction(
+	files: URL[],
+	outDir: URL,
+	exclude: URL[] = []
+): Promise<string> {
+	const excludeList = exclude.map(fileURLToPath);
+	const fileList = files.map(fileURLToPath).filter((f) => !excludeList.includes(f));
+
+	if (files.length === 0) throw new Error('[@astrojs/vercel] No files found to copy');
+
+	let commonAncestor = nodePath.dirname(fileList[0]);
+	for (const file of fileList.slice(1)) {
+		while (!file.startsWith(commonAncestor)) {
+			commonAncestor = nodePath.dirname(commonAncestor);
+		}
+	}
+
+	for (const origin of fileList) {
+		const dest = new URL(nodePath.relative(commonAncestor, origin), outDir);
+
+		const realpath = await fs.realpath(origin);
+		const isSymlink = realpath !== origin;
+		const isDir = (await fs.stat(origin)).isDirectory();
+
+		// Create directories recursively
+		if (isDir && !isSymlink) {
+			await fs.mkdir(new URL('..', dest), { recursive: true });
+		} else {
+			await fs.mkdir(new URL('.', dest), { recursive: true });
+		}
+
+		if (isSymlink) {
+			const realdest = fileURLToPath(new URL(nodePath.relative(commonAncestor, realpath), outDir));
+			await fs.symlink(
+				nodePath.relative(fileURLToPath(new URL('.', dest)), realdest),
+				dest,
+				isDir ? 'dir' : 'file'
+			);
+		} else if (!isDir) {
+			await fs.copyFile(origin, dest);
+		}
+	}
+
+	return commonAncestor;
+}
diff --git a/packages/integrations/vercel/src/lib/nft.ts b/packages/integrations/vercel/src/lib/nft.ts
index ba3677583..6a9ac116e 100644
--- a/packages/integrations/vercel/src/lib/nft.ts
+++ b/packages/integrations/vercel/src/lib/nft.ts
@@ -1,12 +1,20 @@
 import { nodeFileTrace } from '@vercel/nft';
-import * as fs from 'node:fs/promises';
-import nodePath from 'node:path';
+import { relative as relativePath } from 'node:path';
 import { fileURLToPath } from 'node:url';
 
-export async function copyDependenciesToFunction(
-	entry: URL,
-	outDir: URL
-): Promise<{ handler: string }> {
+import { copyFilesToFunction } from './fs.js';
+
+export async function copyDependenciesToFunction({
+	entry,
+	outDir,
+	includeFiles,
+	excludeFiles,
+}: {
+	entry: URL;
+	outDir: URL;
+	includeFiles: URL[];
+	excludeFiles: URL[];
+}): Promise<{ handler: string }> {
 	const entryPath = fileURLToPath(entry);
 
 	// Get root of folder of the system (like C:\ on Windows or / on Linux)
@@ -19,8 +27,6 @@ export async function copyDependenciesToFunction(
 		base: fileURLToPath(base),
 	});
 
-	if (result.fileList.size === 0) throw new Error('[@astrojs/vercel] No files found');
-
 	for (const error of result.warnings) {
 		if (error.message.startsWith('Failed to resolve dependency')) {
 			const [, module, file] = /Cannot find module '(.+?)' loaded from (.+)/.exec(error.message)!;
@@ -42,49 +48,14 @@ export async function copyDependenciesToFunction(
 		}
 	}
 
-	const fileList = [...result.fileList];
-
-	let commonAncestor = nodePath.dirname(fileList[0]);
-	for (const file of fileList.slice(1)) {
-		while (!file.startsWith(commonAncestor)) {
-			commonAncestor = nodePath.dirname(commonAncestor);
-		}
-	}
-
-	for (const file of fileList) {
-		const origin = new URL(file, base);
-		const dest = new URL(nodePath.relative(commonAncestor, file), outDir);
-
-		const realpath = await fs.realpath(origin);
-		const isSymlink = realpath !== fileURLToPath(origin);
-		const isDir = (await fs.stat(origin)).isDirectory();
-
-		// Create directories recursively
-		if (isDir && !isSymlink) {
-			await fs.mkdir(new URL('..', dest), { recursive: true });
-		} else {
-			await fs.mkdir(new URL('.', dest), { recursive: true });
-		}
-
-		if (isSymlink) {
-			const realdest = fileURLToPath(
-				new URL(
-					nodePath.relative(nodePath.join(fileURLToPath(base), commonAncestor), realpath),
-					outDir
-				)
-			);
-			await fs.symlink(
-				nodePath.relative(fileURLToPath(new URL('.', dest)), realdest),
-				dest,
-				isDir ? 'dir' : 'file'
-			);
-		} else if (!isDir) {
-			await fs.copyFile(origin, dest);
-		}
-	}
+	const commonAncestor = await copyFilesToFunction(
+		[...result.fileList].map((file) => new URL(file, base)).concat(includeFiles),
+		outDir,
+		excludeFiles
+	);
 
 	return {
 		// serverEntry location inside the outDir
-		handler: nodePath.relative(nodePath.join(fileURLToPath(base), commonAncestor), entryPath),
+		handler: relativePath(commonAncestor, entryPath),
 	};
 }
diff --git a/packages/integrations/vercel/src/serverless/adapter.ts b/packages/integrations/vercel/src/serverless/adapter.ts
index 5b65c331e..3c7ba15de 100644
--- a/packages/integrations/vercel/src/serverless/adapter.ts
+++ b/packages/integrations/vercel/src/serverless/adapter.ts
@@ -14,7 +14,15 @@ function getAdapter(): AstroAdapter {
 	};
 }
 
-export default function vercelEdge(): AstroIntegration {
+export interface VercelServerlessConfig {
+	includeFiles?: string[];
+	excludeFiles?: string[];
+}
+
+export default function vercelServerless({
+	includeFiles,
+	excludeFiles,
+}: VercelServerlessConfig = {}): AstroIntegration {
 	let _config: AstroConfig;
 	let buildTempFolder: URL;
 	let functionFolder: URL;
@@ -59,10 +67,12 @@ export default function vercelEdge(): AstroIntegration {
 			},
 			'astro:build:done': async ({ routes }) => {
 				// Copy necessary files (e.g. node_modules/)
-				const { handler } = await copyDependenciesToFunction(
-					new URL(serverEntry, buildTempFolder),
-					functionFolder
-				);
+				const { handler } = await copyDependenciesToFunction({
+					entry: new URL(serverEntry, buildTempFolder),
+					outDir: functionFolder,
+					includeFiles: includeFiles?.map((file) => new URL(file, _config.root)) || [],
+					excludeFiles: excludeFiles?.map((file) => new URL(file, _config.root)) || [],
+				});
 
 				// Remove temporary folder
 				await removeDir(buildTempFolder);