Merge pull request #30875 from hudsonb/bhudson/feature-discovery-fix

Fix feature discovery crash with packages using exports fields

.changeset/lovely-cobras-doubt.md

@@ -0,0 +1,5 @@
+---
+'@backstage/backend-defaults': patch
+---
+
+Fixed bug in PackageDiscoveryService where packages with "exports" field caused ERR_PACKAGE_PATH_NOT_EXPORTED error during backend startup.

packages/backend-defaults/src/PackageDiscoveryService.ts

@@ -23,6 +23,7 @@ import {
   RootLoggerService,
 } from '@backstage/backend-plugin-api';
 import { BackstagePackageJson } from '@backstage/cli-node';
+import { isError } from '@backstage/errors';
 
 const DETECTED_PACKAGE_ROLES = [
   'node-library',
@@ -125,9 +126,19 @@ export class PackageDiscoveryService {
     const features: BackendFeature[] = [];
 
     for (const name of dependencyNames) {
-      const depPkg = require(require.resolve(`${name}/package.json`, {
-        paths: [packageDir],
-      })) as BackstagePackageJson;
+      let depPkg: BackstagePackageJson;
+      try {
+        const packageJsonPath = require.resolve(`${name}/package.json`, {
+          paths: [packageDir],
+        });
+        depPkg = require(packageJsonPath) as BackstagePackageJson;
+      } catch (error) {
+        // Handle packages with "exports" field that don't export ./package.json
+        if (isError(error) && error.code === 'ERR_PACKAGE_PATH_NOT_EXPORTED') {
+          continue; // Skip packages that don't export package.json - they can't be Backstage packages
+        }
+        throw error;
+      }
       if (
         !depPkg?.backstage?.role ||
         !DETECTED_PACKAGE_ROLES.includes(depPkg.backstage.role)