From 18b96b15edeb2526bf36c60530e1739cb8d8f274 Mon Sep 17 00:00:00 2001
From: Patrik Oldsberg <poldsberg@gmail.com>
Date: Wed, 10 Jul 2024 13:30:14 +0200
Subject: [PATCH] backend-app-api: deprecate callback form of backend.add(...)

Signed-off-by: Patrik Oldsberg <poldsberg@gmail.com>
---
 .changeset/three-lizards-crash.md            |  5 +++++
 packages/backend-app-api/api-report.md       |  9 ++++++++-
 packages/backend-app-api/src/wiring/types.ts | 11 +++++++++--
 3 files changed, 22 insertions(+), 3 deletions(-)
 create mode 100644 .changeset/three-lizards-crash.md

diff --git a/.changeset/three-lizards-crash.md b/.changeset/three-lizards-crash.md
new file mode 100644
index 0000000000..5dffed0f3b
--- /dev/null
+++ b/.changeset/three-lizards-crash.md
@@ -0,0 +1,5 @@
+---
+'@backstage/backend-app-api': patch
+---
+
+The ability to install backend features in callback form (`() => BackendFeature`) has been deprecated. This typically means that you need to update the installed features to use the latest version of `@backstage/backend-plugin-api`. If the feature is from a third-party package, please reach out to the package maintainer to update it.
diff --git a/packages/backend-app-api/api-report.md b/packages/backend-app-api/api-report.md
index 2a447d52ef..54e2900cc2 100644
--- a/packages/backend-app-api/api-report.md
+++ b/packages/backend-app-api/api-report.md
@@ -58,9 +58,16 @@ export interface Backend {
   add(
     feature:
       | BackendFeature
+      | Promise<{
+          default: BackendFeature;
+        }>,
+  ): void;
+  // @deprecated (undocumented)
+  add(
+    feature:
       | (() => BackendFeature)
       | Promise<{
-          default: BackendFeature | (() => BackendFeature);
+          default: () => BackendFeature;
         }>,
   ): void;
   // (undocumented)
diff --git a/packages/backend-app-api/src/wiring/types.ts b/packages/backend-app-api/src/wiring/types.ts
index 776dcdcb35..075eb58b3f 100644
--- a/packages/backend-app-api/src/wiring/types.ts
+++ b/packages/backend-app-api/src/wiring/types.ts
@@ -25,11 +25,18 @@ import {
  * @public
  */
 export interface Backend {
+  add(feature: BackendFeature | Promise<{ default: BackendFeature }>): void;
+  /**
+   * @deprecated The ability to add features defined as a callback is being
+   * removed. Please update the installed feature to no longer be defined as a
+   * callback, typically this means updating it to use the latest version of
+   * `@backstage/backend-plugin-api`. If the feature is from a third-party
+   * package, please reach out to the package maintainer to update it.
+   */
   add(
     feature:
-      | BackendFeature
       | (() => BackendFeature)
-      | Promise<{ default: BackendFeature | (() => BackendFeature) }>,
+      | Promise<{ default: () => BackendFeature }>,
   ): void;
   start(): Promise<void>;
   stop(): Promise<void>;