[remix] Reinstall dependencies during prepareCache() (#10922)

https://github.com/vercel/vercel/pull/10819 introduced a bug causing the `prepareCache()` function to fail (due to `@remix-run/dev` no longer being require-able). Even if it were not failing, the deps installed are not a valid representation of the user's `package.json` / lockfile. So to have more truthful cache contents, run `npm install` once again during `prepareCache()` to fix both issues at the same time.

.changeset/neat-turkeys-relate.md

@@ -0,0 +1,5 @@
+---
+'@vercel/remix-builder': patch
+---
+
+Reinstall dependencies during `prepareCache()`

packages/remix/src/build.ts

@@ -104,15 +104,17 @@ export const build: BuildV2 = async ({
     meta
   );
 
-  const { cliType, packageJsonPath, lockfileVersion } = await scanParentDirs(
+  const { cliType, packageJsonPath, lockfileVersion, lockfilePath } =
-    entrypointFsDirname
+    await scanParentDirs(entrypointFsDirname);
-  );
 
   if (!packageJsonPath) {
     throw new Error('Failed to locate `package.json` file in your project');
   }
 
-  const pkgRaw = await fs.readFile(packageJsonPath, 'utf8');
+  const [lockfileRaw, pkgRaw] = await Promise.all([
+    lockfilePath ? fs.readFile(lockfilePath) : null,
+    fs.readFile(packageJsonPath, 'utf8'),
+  ]);
   const pkg = JSON.parse(pkgRaw);
 
   const spawnOpts = getSpawnOptions(meta, nodeVersion);
@@ -423,9 +425,7 @@ module.exports = config;`;
       cleanupOps.push(
         fs
           .rename(renamedRemixConfigPath, remixConfigPath)
-          .then(() =>
+          .then(() => debug(`Restored original "${remixConfigPath}" file`))
-            debug(`Restored original "${basename(remixConfigPath)}" file`)
-          )
       );
     }
     // Restore original server entrypoint if it was modified (for Hydrogen v2)
@@ -433,11 +433,24 @@ module.exports = config;`;
       cleanupOps.push(
         fs
           .writeFile(serverEntryPointAbs, originalServerEntryPoint)
-          .then(() =>
+          .then(() => debug(`Restored original "${serverEntryPointAbs}" file`))
-            debug(`Restored original "${basename(serverEntryPointAbs!)}" file`)
-          )
       );
     }
+    // Restore original `package.json` file and lockfile
+    if (depsModified) {
+      cleanupOps.push(
+        fs
+          .writeFile(packageJsonPath, pkgRaw)
+          .then(() => debug(`Restored original "${packageJsonPath}" file`))
+      );
+      if (lockfilePath && lockfileRaw) {
+        cleanupOps.push(
+          fs
+            .writeFile(lockfilePath, lockfileRaw)
+            .then(() => debug(`Restored original "${lockfilePath}" file`))
+        );
+      }
+    }
     await Promise.all(cleanupOps);
   }
 

packages/remix/src/prepare-cache.ts

@@ -1,4 +1,9 @@
-import { glob } from '@vercel/build-utils';
+import {
+  getNodeVersion,
+  getSpawnOptions,
+  glob,
+  runNpmInstall,
+} from '@vercel/build-utils';
 import { dirname, join, relative } from 'path';
 import { require_, chdirAndReadConfig } from './utils';
 import type { PrepareCache } from '@vercel/build-utils';
@@ -7,10 +12,32 @@ export const prepareCache: PrepareCache = async ({
   entrypoint,
   repoRootPath,
   workPath,
+  config,
 }) => {
   const root = repoRootPath || workPath;
   const mountpoint = dirname(entrypoint);
   const entrypointFsDirname = join(workPath, mountpoint);
+
+  // Because the `node_modules` directory was modified to install
+  // the forked Remix compiler, re-install to the "fresh" dependencies
+  // state before the cache gets created.
+  const nodeVersion = await getNodeVersion(
+    entrypointFsDirname,
+    undefined,
+    config
+  );
+  const spawnOpts = getSpawnOptions({}, nodeVersion);
+  await runNpmInstall(
+    entrypointFsDirname,
+    [],
+    {
+      ...spawnOpts,
+      stdio: 'ignore',
+    },
+    undefined,
+    nodeVersion
+  );
+
   const packageJsonPath = join(entrypointFsDirname, 'package.json');
   const remixRunDevPath = dirname(
     require_.resolve('@remix-run/dev/package.json', {