From 7af5f7320f87475a6cc0581105657c295e2516bf Mon Sep 17 00:00:00 2001
From: Vincenzo Scamporlino <vincenzos@spotify.com>
Date: Fri, 11 Aug 2023 00:00:06 +0200
Subject: [PATCH] backend-defaults: remove options from createBackend

Signed-off-by: Vincenzo Scamporlino <vincenzos@spotify.com>
---
 .../src/CreateBackend.test.ts                 | 89 ++++++++++---------
 .../backend-defaults/src/CreateBackend.ts     | 29 +-----
 packages/backend-defaults/src/index.ts        |  1 -
 3 files changed, 48 insertions(+), 71 deletions(-)

diff --git a/packages/backend-defaults/src/CreateBackend.test.ts b/packages/backend-defaults/src/CreateBackend.test.ts
index de04d4e350..0b36b57069 100644
--- a/packages/backend-defaults/src/CreateBackend.test.ts
+++ b/packages/backend-defaults/src/CreateBackend.test.ts
@@ -22,60 +22,63 @@ import { createBackend } from './CreateBackend';
 
 describe('createBackend', () => {
   it('should not throw when overriding a default service implementation', () => {
-    expect(() =>
-      createBackend({
-        services: [
-          createServiceFactory({
-            service: coreServices.rootLifecycle,
-            deps: {},
-            factory: async () => ({
-              addStartupHook: () => {},
-              addShutdownHook: () => {},
-            }),
+    const backend = createBackend();
+
+    expect(() => {
+      backend.add(
+        createServiceFactory({
+          service: coreServices.rootLifecycle,
+          deps: {},
+          factory: async () => ({
+            addStartupHook: () => {},
+            addShutdownHook: () => {},
           }),
-        ],
-      }),
-    ).not.toThrow();
+        }),
+      );
+    }).not.toThrow();
   });
 
   it('should throw on duplicate service implementations', () => {
-    expect(() =>
-      createBackend({
-        services: [
-          createServiceFactory({
-            service: coreServices.rootLifecycle,
-            deps: {},
-            factory: async () => ({
-              addStartupHook: () => {},
-              addShutdownHook: () => {},
-            }),
-          }),
-          createServiceFactory({
-            service: coreServices.rootLifecycle,
-            deps: {},
-            factory: async () => ({
-              addStartupHook: () => {},
-              addShutdownHook: () => {},
-            }),
-          }),
-        ],
+    const backend = createBackend();
+
+    backend.add(
+      createServiceFactory({
+        service: coreServices.rootLifecycle,
+        deps: {},
+        factory: async () => ({
+          addStartupHook: () => {},
+          addShutdownHook: () => {},
+        }),
       }),
-    ).toThrow(
+    );
+
+    expect(() => {
+      backend.add(
+        createServiceFactory({
+          service: coreServices.rootLifecycle,
+          deps: {},
+          factory: async () => ({
+            addStartupHook: () => {},
+            addShutdownHook: () => {},
+          }),
+        }),
+      );
+    }).toThrow(
       'Duplicate service implementations provided for core.rootLifecycle',
     );
   });
 
   it('should throw when providing a plugin metadata service implementation', () => {
+    const backend = createBackend();
+
     expect(() =>
-      createBackend({
-        services: [
-          createServiceFactory({
-            service: coreServices.pluginMetadata,
-            deps: {},
-            factory: async () => ({ getId: () => 'test' }),
-          }),
-        ],
-      }),
+      backend.add(
+        createServiceFactory({
+          service: coreServices.pluginMetadata,
+          deps: {},
+          factory: async () => ({ getId: () => 'test' }),
+        }),
+      ),
     ).toThrow('The core.pluginMetadata service cannot be overridden');
   });
 });
diff --git a/packages/backend-defaults/src/CreateBackend.ts b/packages/backend-defaults/src/CreateBackend.ts
index 3db013a290..c07d1cc38a 100644
--- a/packages/backend-defaults/src/CreateBackend.ts
+++ b/packages/backend-defaults/src/CreateBackend.ts
@@ -33,10 +33,6 @@ import {
   urlReaderServiceFactory,
   identityServiceFactory,
 } from '@backstage/backend-app-api';
-import {
-  ServiceFactory,
-  ServiceFactoryOrFunction,
-} from '@backstage/backend-plugin-api';
 
 export const defaultServiceFactories = [
   cacheServiceFactory(),
@@ -59,27 +55,6 @@ export const defaultServiceFactories = [
 /**
  * @public
  */
-export interface CreateBackendOptions {
-  services?: ServiceFactoryOrFunction[];
-}
-
-/**
- * @public
- */
-export function createBackend(options?: CreateBackendOptions): Backend {
-  const services = new Array<ServiceFactory>();
-
-  // Highest priority: Services passed directly to createBackend
-  const providedServices = (options?.services ?? []).map(sf =>
-    typeof sf === 'function' ? sf() : sf,
-  );
-  services.push(...providedServices);
-
-  // Lowest priority: Default services that are not already provided by environment or directly to createBackend
-  const defaultServices = defaultServiceFactories.filter(
-    sf => !services.some(({ service }) => service.id === sf.service.id),
-  );
-  services.push(...defaultServices);
-
-  return createSpecializedBackend({ services });
+export function createBackend(): Backend {
+  return createSpecializedBackend({ defaultServiceFactories });
 }
diff --git a/packages/backend-defaults/src/index.ts b/packages/backend-defaults/src/index.ts
index 833878744e..d3e36cf0fb 100644
--- a/packages/backend-defaults/src/index.ts
+++ b/packages/backend-defaults/src/index.ts
@@ -25,5 +25,4 @@
 // TODO(Rugvip): Remove this once backend-common is no longer used by backend-app-api
 import '@backstage/backend-common';
 
-export type { CreateBackendOptions } from './CreateBackend';
 export { createBackend } from './CreateBackend';