From 150a7dd7909a7e88ca07c116613e0f73bca4fa9d Mon Sep 17 00:00:00 2001
From: Patrik Oldsberg <poldsberg@gmail.com>
Date: Tue, 3 Jan 2023 11:50:31 +0100
Subject: [PATCH] backend-app-api: throw error if trying to override metadata
 service

Signed-off-by: Patrik Oldsberg <poldsberg@gmail.com>
---
 .changeset/great-forks-lay.md                      |  5 +++++
 packages/backend-app-api/src/wiring/types.ts       |  6 ++++++
 .../backend-defaults/src/CreateBackend.test.ts     | 14 ++++++++++++++
 3 files changed, 25 insertions(+)
 create mode 100644 .changeset/great-forks-lay.md

diff --git a/.changeset/great-forks-lay.md b/.changeset/great-forks-lay.md
new file mode 100644
index 0000000000..6585951062
--- /dev/null
+++ b/.changeset/great-forks-lay.md
@@ -0,0 +1,5 @@
+---
+'@backstage/backend-app-api': patch
+---
+
+An error will now be thrown if attempting to override the plugin metadata service.
diff --git a/packages/backend-app-api/src/wiring/types.ts b/packages/backend-app-api/src/wiring/types.ts
index c591d5cb55..d3ffef731c 100644
--- a/packages/backend-app-api/src/wiring/types.ts
+++ b/packages/backend-app-api/src/wiring/types.ts
@@ -19,6 +19,7 @@ import {
   BackendFeature,
   ExtensionPoint,
   ServiceRef,
+  coreServices,
 } from '@backstage/backend-plugin-api';
 import { BackstageBackend } from './BackstageBackend';
 
@@ -80,6 +81,11 @@ export function createSpecializedBackend(
     const ids = Array.from(duplicates).join(', ');
     throw new Error(`Duplicate service implementations provided for ${ids}`);
   }
+  if (exists.has(coreServices.pluginMetadata.id)) {
+    throw new Error(
+      `The ${coreServices.pluginMetadata.id} service cannot be overridden`,
+    );
+  }
 
   return new BackstageBackend(services);
 }
diff --git a/packages/backend-defaults/src/CreateBackend.test.ts b/packages/backend-defaults/src/CreateBackend.test.ts
index 4b5e2e5848..a05e09df0f 100644
--- a/packages/backend-defaults/src/CreateBackend.test.ts
+++ b/packages/backend-defaults/src/CreateBackend.test.ts
@@ -55,4 +55,18 @@ describe('createBackend', () => {
       'Duplicate service implementations provided for core.rootLifecycle',
     );
   });
+
+  it('should throw when providing a plugin metadata service implementation', () => {
+    expect(() =>
+      createBackend({
+        services: [
+          createServiceFactory({
+            service: coreServices.pluginMetadata,
+            deps: {},
+            factory: async () => async () => ({ getId: () => 'test' }),
+          }),
+        ],
+      }),
+    ).toThrow('The core.plugin-metadata service cannot be overridden');
+  });
 });