fix: Improve Static Server Reliability

package/src/server/index.ts

@@ -1,5 +1,7 @@
 /// <reference types="astro/client" />
-
+import path, { relative } from 'node:path';
+import url from 'node:url';
+import { readdir } from 'node:fs/promises';
 import cluster from 'node:cluster';
 import os from 'node:os';
 
@@ -78,16 +80,25 @@ function handler(
 
   const app = new App(manifest);
 
-  return (req: Request, server: Server): Promise<Response> => {
+  // The dist may be copied somewhere after building.
+  // The build environment's full client path (options.client) can't be relied on in production.
+  // `resolveClientDir()` finds the full path to the client directory in the current environment
+  const clientDir = resolveClientDir(options);
+
+  const clientAssetsPromise = getStaticAssets(clientDir);
+  let clientAssets: Awaited<typeof clientAssetsPromise> | undefined;
+
+  return async (req: Request, server: Server): Promise<Response> => {
     const routeData = app.match(req);
     if (!routeData) {
       const url = new URL(req.url);
-
-      const manifestAssetExists = manifest.assets.has(url.pathname);
+      const staticAssetExists = (clientAssets ??= await clientAssetsPromise).has(
+        url.pathname,
+      );
 
       // If the manifest asset doesn't exist, or the request url ends with a slash
       // we should serve the index.html file from the respective directory.
-      if (!manifestAssetExists || req.url.endsWith('/')) {
+      if (!staticAssetExists || req.url.endsWith('/')) {
         const localPath = new URL(
           `./${app.removeBase(url.pathname)}/index.html`,
           clientRoot,
@@ -96,7 +107,7 @@ function handler(
       }
 
       // Otherwise we attempt to serve the static asset from the client directory.
-      if (manifestAssetExists) {
+      if (staticAssetExists) {
         const localPath = new URL(app.removeBase(url.pathname), clientRoot);
         return serveStaticFile(url.pathname, localPath, clientRoot, options);
       }
@@ -109,3 +120,50 @@ function handler(
     });
   };
 }
+
+async function getStaticAssets(clientDir: string) {
+  const dirEntries = await readdir(clientDir, { withFileTypes: true, recursive: true });
+  const publicPath = new Set<string>();
+  for (const entry of dirEntries) {
+    if (entry.isFile() == false) continue;
+    publicPath.add(
+      prependForwardSlash(path.relative(clientDir, entry.parentPath) + '/' + entry.name),
+    );
+  }
+  return publicPath;
+}
+
+/**
+ * From https://github.com/withastro/adapters/blob/@astrojs/[email protected]/packages/node/src/serve-static.ts#L109-L125
+ *
+ * Copyright of withastro/adapters contributors, Reproduced under MIT License
+ */
+// @ts-expect-error client and server fields are always present
+function resolveClientDir(options: InternalOptions) {
+  const clientURLRaw = new URL(options.client);
+  const serverURLRaw = new URL(options.server);
+  const rel = path.relative(
+    url.fileURLToPath(serverURLRaw),
+    url.fileURLToPath(clientURLRaw),
+  );
+
+  // walk up the parent folders until you find the one that is the root of the server entry folder. This is how we find the client folder relatively.
+  const serverFolder = path.basename(options.server);
+  let serverEntryFolderURL = path.dirname(import.meta.url);
+  while (!serverEntryFolderURL.endsWith(serverFolder)) {
+    serverEntryFolderURL = path.dirname(serverEntryFolderURL);
+  }
+
+  const serverEntryURL = serverEntryFolderURL + '/entry.mjs';
+  const clientURL = new URL(appendForwardSlash(rel), serverEntryURL);
+  const client = url.fileURLToPath(clientURL);
+  return client;
+}
+
+function prependForwardSlash(pth: string) {
+  return pth.startsWith('/') ? pth : '/' + pth;
+}
+
+function appendForwardSlash(pth: string) {
+  return pth.endsWith('/') ? pth : pth + '/';
+}