fix: prevent conflict between Netlify Identity and edge function rendering (#12052)

Previously Netlify Edge Functions didn't support a way to configure path
matching that *excludes* paths.

Now that it does, we can avoid running the "render" edge function on
static assets. Currently, it's [just a
no-op](https://github.com/sveltejs/kit/blob/80386437030c5c79913e859e3c32fd194613e1b6/packages/adapter-netlify/src/edge.js#L18-L22),
but it's still nice to avoid the invocation.

Fixes #5235.

---------

Co-authored-by: Simon Holthausen <[email protected]>
Co-authored-by: Chew Tee Ming <[email protected]>
Co-authored-by: Tee Ming <[email protected]>

Author: 3 people

.changeset/witty-teachers-film.md

@@ -0,0 +1,5 @@
+---
+'@sveltejs/adapter-netlify': patch
+---
+
+fix: avoid unnecessary Netlify edge function invocations for static files, which resolves a conflict between Netlify Edge Functions and Netlify Identity

packages/adapter-netlify/index.js

@@ -14,15 +14,19 @@ import toml from '@iarna/toml';
  */
 
 /**
+ * TODO(serhalp) Replace this custom type with an import from `@netlify/edge-functions`,
+ * once that type is fixed to include `excludedPath` and `function`.
  * @typedef {{
  *	 functions: Array<
  *		 | {
  *				 function: string;
  *				 path: string;
+ *				 excludedPath?: string | string[];
  *		   }
  *		 | {
  *				 function: string;
  *				 pattern: string;
+ *				 excludedPattern?: string | string[];
  *		   }
  *	 >;
  *	 version: 1;
@@ -122,23 +126,6 @@ async function generate_edge_functions({ builder }) {
 
 	builder.mkdirp('.netlify/edge-functions');
 
-	// Don't match the static directory
-	const pattern = '^/.*$';
-
-	// Go doesn't support lookarounds, so we can't do this
-	// const pattern = appDir ? `^/(?!${escapeStringRegexp(appDir)}).*$` : '^/.*$';
-
-	/** @type {HandlerManifest} */
-	const edge_manifest = {
-		functions: [
-			{
-				function: 'render',
-				pattern
-			}
-		],
-		version: 1
-	};
-
 	builder.log.minor('Generating Edge Function...');
 	const relativePath = posix.relative(tmp, builder.getServerDirectory());
 
@@ -153,12 +140,43 @@ async function generate_edge_functions({ builder }) {
 		relativePath
 	});
 
-	writeFileSync(
-		`${tmp}/manifest.js`,
-		`export const manifest = ${manifest};\n\nexport const prerendered = new Set(${JSON.stringify(
-			builder.prerendered.paths
-		)});\n`
-	);
+	writeFileSync(`${tmp}/manifest.js`, `export const manifest = ${manifest};\n`);
+
+	/** @type {{ assets: Set<string> }} */
+	const { assets } = (await import(`${tmp}/manifest.js`)).manifest;
+
+	const path = '/*';
+	// We only need to specify paths without the trailing slash because
+	// Netlify will handle the optional trailing slash for us
+	const excludedPath = [
+		// Contains static files
+		`/${builder.getAppPath()}/*`,
+		...builder.prerendered.paths,
+		...Array.from(assets).flatMap((asset) => {
+			if (asset.endsWith('/index.html')) {
+				const dir = asset.replace(/\/index\.html$/, '');
+				return [
+					`${builder.config.kit.paths.base}/${asset}`,
+					`${builder.config.kit.paths.base}/${dir}`
+				];
+			}
+			return `${builder.config.kit.paths.base}/${asset}`;
+		}),
+		// Should not be served by SvelteKit at all
+		'/.netlify/*'
+	];
+
+	/** @type {HandlerManifest} */
+	const edge_manifest = {
+		functions: [
+			{
+				function: 'render',
+				path,
+				excludedPath
+			}
+		],
+		version: 1
+	};
 
 	await esbuild.build({
 		entryPoints: [`${tmp}/entry.js`],

packages/adapter-netlify/internal.d.ts

@@ -6,5 +6,4 @@ declare module 'MANIFEST' {
 	import { SSRManifest } from '@sveltejs/kit';
 
 	export const manifest: SSRManifest;
-	export const prerendered: Set<string>;
 }

packages/adapter-netlify/src/edge.js

@@ -1,8 +1,7 @@
 import { Server } from '0SERVER';
-import { manifest, prerendered } from 'MANIFEST';
+import { manifest } from 'MANIFEST';
 
 const server = new Server(manifest);
-const prefix = `/${manifest.appPath}/`;
 
 const initialized = server.init({
 	// @ts-ignore
@@ -15,12 +14,6 @@ const initialized = server.init({
  * @returns { Promise<Response> }
  */
 export default async function handler(request, context) {
-	if (is_static_file(request)) {
-		// Static files can skip the handler
-		// TODO can we serve _app/immutable files with an immutable cache header?
-		return;
-	}
-
 	await initialized;
 	return server.respond(request, {
 		platform: { context },
@@ -29,33 +22,3 @@ export default async function handler(request, context) {
 		}
 	});
 }
-
-/**
- * @param {Request} request
- */
-function is_static_file(request) {
-	const url = new URL(request.url);
-
-	// Assets in the app dir
-	if (url.pathname.startsWith(prefix)) {
-		return true;
-	}
-
-	// prerendered pages and index.html files
-	const pathname = url.pathname.replace(/\/$/, '');
-	let file = pathname.substring(1);
-
-	try {
-		file = decodeURIComponent(file);
-	} catch {
-		// ignore
-	}
-
-	return (
-		manifest.assets.has(file) ||
-		manifest.assets.has(file + '/index.html') ||
-		file in manifest._.server_assets ||
-		file + '/index.html' in manifest._.server_assets ||
-		prerendered.has(pathname || '/')
-	);
-}