From e20346c25c7c08a494a1198adbf9fe075135b4dd Mon Sep 17 00:00:00 2001
From: Oleg S <97077423+RobotSail@users.noreply.github.com>
Date: Tue, 28 Feb 2023 09:22:07 -0500
Subject: [PATCH 1/9] add types to function signatures

Signed-off-by: Oleg S <97077423+RobotSail@users.noreply.github.com>
---
 packages/config-loader/src/loader.ts | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/packages/config-loader/src/loader.ts b/packages/config-loader/src/loader.ts
index f5ce0eb80c..69b0e04b86 100644
--- a/packages/config-loader/src/loader.ts
+++ b/packages/config-loader/src/loader.ts
@@ -139,8 +139,11 @@ export async function loadConfig(
 
   const env = envFunc ?? (async (name: string) => process.env[name]);
 
-  const loadConfigFiles = async () => {
-    const fileConfigs = [];
+  const loadConfigFiles = async (): Promise<{
+    fileConfigs: AppConfig[];
+    loadedPaths: Set<string>;
+  }> => {
+    const fileConfigs: AppConfig[] = [];
     const loadedPaths = new Set<string>();
 
     for (const configPath of configPaths) {
@@ -176,7 +179,7 @@ export async function loadConfig(
     return { fileConfigs, loadedPaths };
   };
 
-  const loadRemoteConfigFiles = async () => {
+  const loadRemoteConfigFiles = async (): Promise<AppConfig[]> => {
     const configs: AppConfig[] = [];
 
     const readConfigFromUrl = async (url: string) => {

From 15d0bb68e5bf1332234f248af4ec1124378f6d43 Mon Sep 17 00:00:00 2001
From: Oleg S <97077423+RobotSail@users.noreply.github.com>
Date: Tue, 28 Feb 2023 09:26:48 -0500
Subject: [PATCH 2/9] allow configs to be passed directly to loadBackendConfig

Signed-off-by: Oleg S <97077423+RobotSail@users.noreply.github.com>
---
 .../src/config/ObservableConfigProxy.ts       |  9 ++-
 packages/backend-app-api/src/config/config.ts |  6 +-
 packages/types/src/index.ts                   |  1 +
 packages/types/src/json.ts                    | 58 +++++++++++++++++++
 4 files changed, 71 insertions(+), 3 deletions(-)

diff --git a/packages/backend-app-api/src/config/ObservableConfigProxy.ts b/packages/backend-app-api/src/config/ObservableConfigProxy.ts
index dd3334c9a5..485dc60901 100644
--- a/packages/backend-app-api/src/config/ObservableConfigProxy.ts
+++ b/packages/backend-app-api/src/config/ObservableConfigProxy.ts
@@ -16,7 +16,8 @@
 
 import { ConfigService } from '@backstage/backend-plugin-api';
 import { ConfigReader } from '@backstage/config';
-import { JsonValue } from '@backstage/types';
+import type { JsonObject, JsonValue } from '@backstage/types';
+import { mergeJson } from '@backstage/types';
 
 export class ObservableConfigProxy implements ConfigService {
   private config: ConfigService = new ConfigReader({});
@@ -61,6 +62,12 @@ export class ObservableConfigProxy implements ConfigService {
       },
     };
   }
+  mergeConfig(configData: JsonObject) {
+    if (this.parent) {
+      throw new Error('immutable');
+    }
+    this.setConfig(new ConfigReader(mergeJson(this.config.get(), configData)));
+  }
 
   private select(required: true): ConfigService;
   private select(required: false): ConfigService | undefined;
diff --git a/packages/backend-app-api/src/config/config.ts b/packages/backend-app-api/src/config/config.ts
index d3349b41ef..50da0d78b6 100644
--- a/packages/backend-app-api/src/config/config.ts
+++ b/packages/backend-app-api/src/config/config.ts
@@ -24,10 +24,11 @@ import {
   ConfigTarget,
   LoadConfigOptionsRemote,
 } from '@backstage/config-loader';
-import { Config, ConfigReader } from '@backstage/config';
+import { type Config, ConfigReader } from '@backstage/config';
 import { getPackages } from '@manypkg/get-packages';
 import { ObservableConfigProxy } from './ObservableConfigProxy';
 import { isValidUrl } from '../lib/urls';
+import type { JsonObject } from '@backstage/types';
 
 /** @public */
 export async function createConfigSecretEnumerator(options: {
@@ -70,6 +71,7 @@ export async function createConfigSecretEnumerator(options: {
 export async function loadBackendConfig(options: {
   remote?: LoadConfigOptionsRemote;
   argv: string[];
+  config?: JsonObject;
 }): Promise<{ config: Config }> {
   const args = parseArgs(options.argv);
 
@@ -109,12 +111,12 @@ export async function loadBackendConfig(options: {
       }),
     },
   });
-
   console.info(
     `Loaded config from ${appConfigs.map(c => c.context).join(', ')}`,
   );
 
   config.setConfig(ConfigReader.fromConfigs(appConfigs));
+  config.mergeConfig(options.config ?? {});
 
   return { config };
 }
diff --git a/packages/types/src/index.ts b/packages/types/src/index.ts
index 0b5c8689b3..52b0b03622 100644
--- a/packages/types/src/index.ts
+++ b/packages/types/src/index.ts
@@ -21,5 +21,6 @@
  */
 
 export type { JsonArray, JsonObject, JsonPrimitive, JsonValue } from './json';
+export { mergeJson } from './json';
 export type { Observable, Observer, Subscription } from './observable';
 export type { HumanDuration } from './time';
diff --git a/packages/types/src/json.ts b/packages/types/src/json.ts
index bcbaaa1030..1bfe0c543f 100644
--- a/packages/types/src/json.ts
+++ b/packages/types/src/json.ts
@@ -41,3 +41,61 @@ export interface JsonArray extends Array<JsonValue> {}
  * @public
  */
 export type JsonValue = JsonObject | JsonArray | JsonPrimitive;
+
+/**
+ * Attempts to merge two JsonObjects together. In the case of collisions, this function
+ * prefers values from b, unless the value is an object, in which case it recursively
+ * merges the values.
+ *
+ * @param a The base object
+ * @param b The object to merge into a
+ * @returns The merged object
+ */
+export const mergeJson = (a: JsonObject, b: JsonObject): JsonObject => {
+  const final: JsonObject = {};
+  const bKeys = new Set(Object.keys(b));
+  const aKeys = new Set(Object.keys(a));
+  const intersectingKeys = new Set([...aKeys].filter(x => bKeys.has(x)));
+
+  // add all mutually exclusive keys to the final object
+  for (const key of aKeys.values()) {
+    if (!intersectingKeys.has(key)) {
+      final[key] = a[key];
+      continue;
+    }
+  }
+  for (const key of bKeys.values()) {
+    if (!intersectingKeys.has(key)) {
+      final[key] = b[key];
+      continue;
+    }
+  }
+
+  // values now are all overlapping and are either primitives, arrays, or objects.
+  // for all primitives and arrays, we want to assign the value from b
+  // for all objects, we want to recursively merge the values
+  for (const key of intersectingKeys.values()) {
+    // check if value is an array or primitive
+    const value = b[key];
+    if (Array.isArray(value) || typeof value !== 'object') {
+      final[key] = value;
+      continue;
+    }
+
+    // check if either value is undefined and default to the defined one
+    const aValue = a[key];
+    const bValue = b[key];
+    if (!aValue) {
+      final[key] = bValue;
+      continue;
+    }
+    if (!bValue) {
+      final[key] = aValue;
+      continue;
+    }
+
+    // recursively merge the values
+    final[key] = mergeJson(aValue as JsonObject, bValue as JsonObject);
+  }
+  return final;
+};

From e504c73555c770a898c8df3f7be88548ee948c87 Mon Sep 17 00:00:00 2001
From: Oleg S <97077423+RobotSail@users.noreply.github.com>
Date: Wed, 1 Mar 2023 14:02:17 -0500
Subject: [PATCH 3/9] test merging json objects

Signed-off-by: Oleg S <97077423+RobotSail@users.noreply.github.com>
---
 .changeset/spotty-cougars-wink.md      |  7 ++
 packages/backend-app-api/api-report.md |  1 +
 packages/types/api-report.md           |  3 +
 packages/types/src/json.test.ts        | 94 +++++++++++++++++++++++++-
 packages/types/src/json.ts             |  5 +-
 5 files changed, 107 insertions(+), 3 deletions(-)
 create mode 100644 .changeset/spotty-cougars-wink.md

diff --git a/.changeset/spotty-cougars-wink.md b/.changeset/spotty-cougars-wink.md
new file mode 100644
index 0000000000..4e8b97a164
--- /dev/null
+++ b/.changeset/spotty-cougars-wink.md
@@ -0,0 +1,7 @@
+---
+'@backstage/backend-app-api': minor
+'@backstage/config-loader': minor
+'@backstage/types': minor
+---
+
+Introduces the ability to merge configs and JsonObjects
diff --git a/packages/backend-app-api/api-report.md b/packages/backend-app-api/api-report.md
index e99135b3ec..ed84730fc0 100644
--- a/packages/backend-app-api/api-report.md
+++ b/packages/backend-app-api/api-report.md
@@ -178,6 +178,7 @@ export const lifecycleServiceFactory: () => ServiceFactory<
 export function loadBackendConfig(options: {
   remote?: LoadConfigOptionsRemote;
   argv: string[];
+  config?: JsonObject;
 }): Promise<{
   config: Config;
 }>;
diff --git a/packages/types/api-report.md b/packages/types/api-report.md
index 4b43f5daa6..e0b34203cf 100644
--- a/packages/types/api-report.md
+++ b/packages/types/api-report.md
@@ -29,6 +29,9 @@ export type JsonPrimitive = number | string | boolean | null;
 // @public
 export type JsonValue = JsonObject | JsonArray | JsonPrimitive;
 
+// @public
+export const mergeJson: (a: JsonObject, b: JsonObject) => JsonObject;
+
 // @public
 export type Observable<T> = {
   [Symbol.observable](): Observable<T>;
diff --git a/packages/types/src/json.test.ts b/packages/types/src/json.test.ts
index 7da0ef8a3e..277992f00f 100644
--- a/packages/types/src/json.test.ts
+++ b/packages/types/src/json.test.ts
@@ -14,7 +14,13 @@
  * limitations under the License.
  */
 
-import { JsonPrimitive, JsonArray, JsonObject, JsonValue } from './json';
+import {
+  JsonPrimitive,
+  JsonArray,
+  JsonObject,
+  JsonValue,
+  mergeJson,
+} from './json';
 
 describe('json', () => {
   it('JsonPrimitive', () => {
@@ -79,3 +85,89 @@ describe('json', () => {
     expect(true).toBe(true);
   });
 });
+
+describe('jsonMerge', () => {
+  it('should merge two objects', () => {
+    const obj1 = { a: 1, b: 2, c: 3 };
+    const obj2 = { b: 4, c: 5, d: 6 };
+    const merged = mergeJson(obj1, obj2);
+    expect(merged).toEqual({ a: 1, b: 4, c: 5, d: 6 });
+  });
+
+  it('should always prefer to merge the values of the second parameter', () => {
+    const obj1 = {
+      a: 1,
+      b: [1, 2, 3],
+      c: {
+        z: 1,
+        y: 2,
+        x: 3,
+      },
+    };
+    const obj2 = {
+      a: 2,
+      b: [2, 4, 6],
+      c: {
+        z: 2,
+        y: 4,
+        x: 6,
+      },
+    };
+    const merged = mergeJson(obj1, obj2);
+    expect(merged).toEqual(obj2);
+  });
+
+  it('should prefer the second argument whenever keys collide', () => {
+    const obj1 = {
+      a: 1,
+      b: [1, 2, 3],
+      c: {
+        z: 1,
+        y: 2,
+        x: 3,
+      },
+    };
+    const obj2 = {
+      a: 2,
+      c: {
+        y: 4,
+      },
+    };
+    const merged = mergeJson(obj1, obj2);
+    expect(merged).toEqual({
+      a: 2,
+      b: [1, 2, 3],
+      c: {
+        z: 1,
+        y: 4,
+        x: 3,
+      },
+    });
+  });
+
+  it('should merge recursively', () => {
+    const obj1 = {
+      backend: {
+        database: {
+          provider: 'sqlite3',
+        },
+      },
+    };
+    const obj2 = {
+      backend: {
+        database: {
+          password: 'password123',
+        },
+      },
+    };
+    const merged = mergeJson(obj1, obj2);
+    expect(merged).toEqual({
+      backend: {
+        database: {
+          provider: 'sqlite3',
+          password: 'password123',
+        },
+      },
+    });
+  });
+});
diff --git a/packages/types/src/json.ts b/packages/types/src/json.ts
index 1bfe0c543f..4b0bb958ef 100644
--- a/packages/types/src/json.ts
+++ b/packages/types/src/json.ts
@@ -47,9 +47,10 @@ export type JsonValue = JsonObject | JsonArray | JsonPrimitive;
  * prefers values from b, unless the value is an object, in which case it recursively
  * merges the values.
  *
- * @param a The base object
- * @param b The object to merge into a
+ * @param a - The base object
+ * @param b - The object to merge into a
  * @returns The merged object
+ * @public
  */
 export const mergeJson = (a: JsonObject, b: JsonObject): JsonObject => {
   const final: JsonObject = {};

From bf828dea7f5b7e22f0eeeeba12769f04b9f9075e Mon Sep 17 00:00:00 2001
From: Oleg S <97077423+RobotSail@users.noreply.github.com>
Date: Thu, 2 Mar 2023 09:07:09 -0500
Subject: [PATCH 4/9] test merging arrays and undefined objects

Signed-off-by: Oleg S <97077423+RobotSail@users.noreply.github.com>
---
 packages/types/src/json.test.ts | 35 +++++++++++++++++++++++++++++++++
 1 file changed, 35 insertions(+)

diff --git a/packages/types/src/json.test.ts b/packages/types/src/json.test.ts
index 277992f00f..1210d0a773 100644
--- a/packages/types/src/json.test.ts
+++ b/packages/types/src/json.test.ts
@@ -170,4 +170,39 @@ describe('jsonMerge', () => {
       },
     });
   });
+
+  it("should overwrite the array with the second argument's array", () => {
+    const obj1 = {
+      array: ['a', 'b', 'c'],
+    };
+    const obj2 = {
+      array: [1, 2, 3],
+    };
+    const merged = mergeJson(obj1, obj2);
+    expect(merged).toEqual({
+      array: [1, 2, 3],
+    });
+
+    const merged2 = mergeJson(obj2, obj1);
+    expect(merged2).toEqual({
+      array: ['a', 'b', 'c'],
+    });
+  });
+
+  it('should take only the defined value in the case of a collision', () => {
+    const obj1 = {
+      sqlite: undefined,
+    };
+    const obj2 = {
+      sqlite: 'sqlite3',
+    };
+    const merged = mergeJson(obj1, obj2);
+    expect(merged).toEqual({
+      sqlite: 'sqlite3',
+    });
+    const merged2 = mergeJson(obj2, obj1);
+    expect(merged2).toEqual({
+      sqlite: 'sqlite3',
+    });
+  });
 });

From 1fbb7e68077b754bbd9b863936e12622d3a313fa Mon Sep 17 00:00:00 2001
From: Oleg S <97077423+RobotSail@users.noreply.github.com>
Date: Thu, 2 Mar 2023 09:34:00 -0500
Subject: [PATCH 5/9] make sure undefined valeus are weeded out first

Signed-off-by: Oleg S <97077423+RobotSail@users.noreply.github.com>
---
 packages/types/src/json.ts | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/packages/types/src/json.ts b/packages/types/src/json.ts
index 4b0bb958ef..46b5cf9499 100644
--- a/packages/types/src/json.ts
+++ b/packages/types/src/json.ts
@@ -76,13 +76,6 @@ export const mergeJson = (a: JsonObject, b: JsonObject): JsonObject => {
   // for all primitives and arrays, we want to assign the value from b
   // for all objects, we want to recursively merge the values
   for (const key of intersectingKeys.values()) {
-    // check if value is an array or primitive
-    const value = b[key];
-    if (Array.isArray(value) || typeof value !== 'object') {
-      final[key] = value;
-      continue;
-    }
-
     // check if either value is undefined and default to the defined one
     const aValue = a[key];
     const bValue = b[key];
@@ -95,6 +88,13 @@ export const mergeJson = (a: JsonObject, b: JsonObject): JsonObject => {
       continue;
     }
 
+    // check if value is an array or primitive
+    const value = bValue;
+    if (Array.isArray(value) || typeof value !== 'object') {
+      final[key] = value;
+      continue;
+    }
+
     // recursively merge the values
     final[key] = mergeJson(aValue as JsonObject, bValue as JsonObject);
   }

From 5c7ce5858247eefef610a69c3dec80a5db48eae2 Mon Sep 17 00:00:00 2001
From: Oleg S <97077423+RobotSail@users.noreply.github.com>
Date: Wed, 8 Mar 2023 10:07:01 -0500
Subject: [PATCH 6/9] allow an additional config to be provided to
 loadBackendConfig during runtime

Signed-off-by: Oleg S <97077423+RobotSail@users.noreply.github.com>
---
 .changeset/curly-steaks-mate.md               |   7 +
 .changeset/spotty-cougars-wink.md             |   1 -
 packages/backend-app-api/api-report.md        |   3 +-
 .../src/config/ObservableConfigProxy.ts       |   9 +-
 packages/backend-app-api/src/config/config.ts |  12 +-
 packages/backend-common/api-report.md         |   3 +
 packages/backend-common/src/config.ts         |   3 +-
 packages/types/api-report.md                  |   3 -
 packages/types/src/index.ts                   |   1 -
 packages/types/src/json.test.ts               | 129 +-----------------
 packages/types/src/json.ts                    |  59 --------
 11 files changed, 24 insertions(+), 206 deletions(-)
 create mode 100644 .changeset/curly-steaks-mate.md

diff --git a/.changeset/curly-steaks-mate.md b/.changeset/curly-steaks-mate.md
new file mode 100644
index 0000000000..6f32f27a6d
--- /dev/null
+++ b/.changeset/curly-steaks-mate.md
@@ -0,0 +1,7 @@
+---
+'@backstage/backend-app-api': minor
+'@backstage/backend-common': minor
+'@backstage/config-loader': minor
+---
+
+Allow an additionalConfig to be provided to loadBackendConfig that fetches config values during runtime.
diff --git a/.changeset/spotty-cougars-wink.md b/.changeset/spotty-cougars-wink.md
index 4e8b97a164..ca3effe724 100644
--- a/.changeset/spotty-cougars-wink.md
+++ b/.changeset/spotty-cougars-wink.md
@@ -1,7 +1,6 @@
 ---
 '@backstage/backend-app-api': minor
 '@backstage/config-loader': minor
-'@backstage/types': minor
 ---
 
 Introduces the ability to merge configs and JsonObjects
diff --git a/packages/backend-app-api/api-report.md b/packages/backend-app-api/api-report.md
index ed84730fc0..6ef023333b 100644
--- a/packages/backend-app-api/api-report.md
+++ b/packages/backend-app-api/api-report.md
@@ -5,6 +5,7 @@
 ```ts
 /// <reference types="node" />
 
+import type { AppConfig } from '@backstage/config';
 import { BackendFeature } from '@backstage/backend-plugin-api';
 import { CacheClient } from '@backstage/backend-common';
 import { Config } from '@backstage/config';
@@ -178,7 +179,7 @@ export const lifecycleServiceFactory: () => ServiceFactory<
 export function loadBackendConfig(options: {
   remote?: LoadConfigOptionsRemote;
   argv: string[];
-  config?: JsonObject;
+  additionalConfig?: AppConfig;
 }): Promise<{
   config: Config;
 }>;
diff --git a/packages/backend-app-api/src/config/ObservableConfigProxy.ts b/packages/backend-app-api/src/config/ObservableConfigProxy.ts
index 485dc60901..8e0ad218e9 100644
--- a/packages/backend-app-api/src/config/ObservableConfigProxy.ts
+++ b/packages/backend-app-api/src/config/ObservableConfigProxy.ts
@@ -16,8 +16,7 @@
 
 import { ConfigService } from '@backstage/backend-plugin-api';
 import { ConfigReader } from '@backstage/config';
-import type { JsonObject, JsonValue } from '@backstage/types';
-import { mergeJson } from '@backstage/types';
+import type { JsonValue } from '@backstage/types';
 
 export class ObservableConfigProxy implements ConfigService {
   private config: ConfigService = new ConfigReader({});
@@ -62,12 +61,6 @@ export class ObservableConfigProxy implements ConfigService {
       },
     };
   }
-  mergeConfig(configData: JsonObject) {
-    if (this.parent) {
-      throw new Error('immutable');
-    }
-    this.setConfig(new ConfigReader(mergeJson(this.config.get(), configData)));
-  }
 
   private select(required: true): ConfigService;
   private select(required: false): ConfigService | undefined;
diff --git a/packages/backend-app-api/src/config/config.ts b/packages/backend-app-api/src/config/config.ts
index 50da0d78b6..668226e8b2 100644
--- a/packages/backend-app-api/src/config/config.ts
+++ b/packages/backend-app-api/src/config/config.ts
@@ -24,11 +24,11 @@ import {
   ConfigTarget,
   LoadConfigOptionsRemote,
 } from '@backstage/config-loader';
-import { type Config, ConfigReader } from '@backstage/config';
+import { ConfigReader } from '@backstage/config';
+import type { Config, AppConfig } from '@backstage/config';
 import { getPackages } from '@manypkg/get-packages';
 import { ObservableConfigProxy } from './ObservableConfigProxy';
 import { isValidUrl } from '../lib/urls';
-import type { JsonObject } from '@backstage/types';
 
 /** @public */
 export async function createConfigSecretEnumerator(options: {
@@ -71,7 +71,7 @@ export async function createConfigSecretEnumerator(options: {
 export async function loadBackendConfig(options: {
   remote?: LoadConfigOptionsRemote;
   argv: string[];
-  config?: JsonObject;
+  additionalConfig?: AppConfig;
 }): Promise<{ config: Config }> {
   const args = parseArgs(options.argv);
 
@@ -115,8 +115,12 @@ export async function loadBackendConfig(options: {
     `Loaded config from ${appConfigs.map(c => c.context).join(', ')}`,
   );
 
+  // add the additional config if provided
+  if (options.additionalConfig) {
+    appConfigs.push(options.additionalConfig);
+  }
+
   config.setConfig(ConfigReader.fromConfigs(appConfigs));
-  config.mergeConfig(options.config ?? {});
 
   return { config };
 }
diff --git a/packages/backend-common/api-report.md b/packages/backend-common/api-report.md
index ebdd7315c9..a37b5874a3 100644
--- a/packages/backend-common/api-report.md
+++ b/packages/backend-common/api-report.md
@@ -7,6 +7,8 @@
 /// <reference types="webpack-env" />
 
 import { AwsCredentialsManager } from '@backstage/integration-aws-node';
+import type { AppConfig } from '@backstage/config';
+import aws from 'aws-sdk';
 import { AwsS3Integration } from '@backstage/integration';
 import { AzureIntegration } from '@backstage/integration';
 import { BackendFeature } from '@backstage/backend-plugin-api';
@@ -532,6 +534,7 @@ export const legacyPlugin: (
 export function loadBackendConfig(options: {
   logger: LoggerService;
   remote?: LoadConfigOptionsRemote;
+  additionalConfig?: AppConfig;
   argv: string[];
 }): Promise<Config>;
 
diff --git a/packages/backend-common/src/config.ts b/packages/backend-common/src/config.ts
index dd96a6b46a..47316cfd6e 100644
--- a/packages/backend-common/src/config.ts
+++ b/packages/backend-common/src/config.ts
@@ -19,7 +19,7 @@ import {
   loadBackendConfig as newLoadBackendConfig,
 } from '@backstage/backend-app-api';
 import { LoggerService } from '@backstage/backend-plugin-api';
-import { Config } from '@backstage/config';
+import type { AppConfig, Config } from '@backstage/config';
 import { LoadConfigOptionsRemote } from '@backstage/config-loader';
 import { setRootLoggerRedactionList } from './logging/createRootLogger';
 
@@ -34,6 +34,7 @@ export async function loadBackendConfig(options: {
   logger: LoggerService;
   // process.argv or any other overrides
   remote?: LoadConfigOptionsRemote;
+  additionalConfig?: AppConfig;
   argv: string[];
 }): Promise<Config> {
   const secretEnumerator = await createConfigSecretEnumerator({
diff --git a/packages/types/api-report.md b/packages/types/api-report.md
index e0b34203cf..4b43f5daa6 100644
--- a/packages/types/api-report.md
+++ b/packages/types/api-report.md
@@ -29,9 +29,6 @@ export type JsonPrimitive = number | string | boolean | null;
 // @public
 export type JsonValue = JsonObject | JsonArray | JsonPrimitive;
 
-// @public
-export const mergeJson: (a: JsonObject, b: JsonObject) => JsonObject;
-
 // @public
 export type Observable<T> = {
   [Symbol.observable](): Observable<T>;
diff --git a/packages/types/src/index.ts b/packages/types/src/index.ts
index 52b0b03622..0b5c8689b3 100644
--- a/packages/types/src/index.ts
+++ b/packages/types/src/index.ts
@@ -21,6 +21,5 @@
  */
 
 export type { JsonArray, JsonObject, JsonPrimitive, JsonValue } from './json';
-export { mergeJson } from './json';
 export type { Observable, Observer, Subscription } from './observable';
 export type { HumanDuration } from './time';
diff --git a/packages/types/src/json.test.ts b/packages/types/src/json.test.ts
index 1210d0a773..7da0ef8a3e 100644
--- a/packages/types/src/json.test.ts
+++ b/packages/types/src/json.test.ts
@@ -14,13 +14,7 @@
  * limitations under the License.
  */
 
-import {
-  JsonPrimitive,
-  JsonArray,
-  JsonObject,
-  JsonValue,
-  mergeJson,
-} from './json';
+import { JsonPrimitive, JsonArray, JsonObject, JsonValue } from './json';
 
 describe('json', () => {
   it('JsonPrimitive', () => {
@@ -85,124 +79,3 @@ describe('json', () => {
     expect(true).toBe(true);
   });
 });
-
-describe('jsonMerge', () => {
-  it('should merge two objects', () => {
-    const obj1 = { a: 1, b: 2, c: 3 };
-    const obj2 = { b: 4, c: 5, d: 6 };
-    const merged = mergeJson(obj1, obj2);
-    expect(merged).toEqual({ a: 1, b: 4, c: 5, d: 6 });
-  });
-
-  it('should always prefer to merge the values of the second parameter', () => {
-    const obj1 = {
-      a: 1,
-      b: [1, 2, 3],
-      c: {
-        z: 1,
-        y: 2,
-        x: 3,
-      },
-    };
-    const obj2 = {
-      a: 2,
-      b: [2, 4, 6],
-      c: {
-        z: 2,
-        y: 4,
-        x: 6,
-      },
-    };
-    const merged = mergeJson(obj1, obj2);
-    expect(merged).toEqual(obj2);
-  });
-
-  it('should prefer the second argument whenever keys collide', () => {
-    const obj1 = {
-      a: 1,
-      b: [1, 2, 3],
-      c: {
-        z: 1,
-        y: 2,
-        x: 3,
-      },
-    };
-    const obj2 = {
-      a: 2,
-      c: {
-        y: 4,
-      },
-    };
-    const merged = mergeJson(obj1, obj2);
-    expect(merged).toEqual({
-      a: 2,
-      b: [1, 2, 3],
-      c: {
-        z: 1,
-        y: 4,
-        x: 3,
-      },
-    });
-  });
-
-  it('should merge recursively', () => {
-    const obj1 = {
-      backend: {
-        database: {
-          provider: 'sqlite3',
-        },
-      },
-    };
-    const obj2 = {
-      backend: {
-        database: {
-          password: 'password123',
-        },
-      },
-    };
-    const merged = mergeJson(obj1, obj2);
-    expect(merged).toEqual({
-      backend: {
-        database: {
-          provider: 'sqlite3',
-          password: 'password123',
-        },
-      },
-    });
-  });
-
-  it("should overwrite the array with the second argument's array", () => {
-    const obj1 = {
-      array: ['a', 'b', 'c'],
-    };
-    const obj2 = {
-      array: [1, 2, 3],
-    };
-    const merged = mergeJson(obj1, obj2);
-    expect(merged).toEqual({
-      array: [1, 2, 3],
-    });
-
-    const merged2 = mergeJson(obj2, obj1);
-    expect(merged2).toEqual({
-      array: ['a', 'b', 'c'],
-    });
-  });
-
-  it('should take only the defined value in the case of a collision', () => {
-    const obj1 = {
-      sqlite: undefined,
-    };
-    const obj2 = {
-      sqlite: 'sqlite3',
-    };
-    const merged = mergeJson(obj1, obj2);
-    expect(merged).toEqual({
-      sqlite: 'sqlite3',
-    });
-    const merged2 = mergeJson(obj2, obj1);
-    expect(merged2).toEqual({
-      sqlite: 'sqlite3',
-    });
-  });
-});
diff --git a/packages/types/src/json.ts b/packages/types/src/json.ts
index 46b5cf9499..bcbaaa1030 100644
--- a/packages/types/src/json.ts
+++ b/packages/types/src/json.ts
@@ -41,62 +41,3 @@ export interface JsonArray extends Array<JsonValue> {}
  * @public
  */
 export type JsonValue = JsonObject | JsonArray | JsonPrimitive;
-
-/**
- * Attempts to merge two JsonObjects together. In the case of collisions, this function
- * prefers values from b, unless the value is an object, in which case it recursively
- * merges the values.
- *
- * @param a - The base object
- * @param b - The object to merge into a
- * @returns The merged object
- * @public
- */
-export const mergeJson = (a: JsonObject, b: JsonObject): JsonObject => {
-  const final: JsonObject = {};
-  const bKeys = new Set(Object.keys(b));
-  const aKeys = new Set(Object.keys(a));
-  const intersectingKeys = new Set([...aKeys].filter(x => bKeys.has(x)));
-
-  // add all mutually exclusive keys to the final object
-  for (const key of aKeys.values()) {
-    if (!intersectingKeys.has(key)) {
-      final[key] = a[key];
-      continue;
-    }
-  }
-  for (const key of bKeys.values()) {
-    if (!intersectingKeys.has(key)) {
-      final[key] = b[key];
-      continue;
-    }
-  }
-
-  // values now are all overlapping and are either primitives, arrays, or objects.
-  // for all primitives and arrays, we want to assign the value from b
-  // for all objects, we want to recursively merge the values
-  for (const key of intersectingKeys.values()) {
-    // check if either value is undefined and default to the defined one
-    const aValue = a[key];
-    const bValue = b[key];
-    if (!aValue) {
-      final[key] = bValue;
-      continue;
-    }
-    if (!bValue) {
-      final[key] = aValue;
-      continue;
-    }
-
-    // check if value is an array or primitive
-    const value = bValue;
-    if (Array.isArray(value) || typeof value !== 'object') {
-      final[key] = value;
-      continue;
-    }
-
-    // recursively merge the values
-    final[key] = mergeJson(aValue as JsonObject, bValue as JsonObject);
-  }
-  return final;
-};

From 3ca229276dcd69134d204b8eee5d04d59b302cdf Mon Sep 17 00:00:00 2001
From: Oleg S <97077423+RobotSail@users.noreply.github.com>
Date: Wed, 8 Mar 2023 14:10:36 -0500
Subject: [PATCH 7/9] allow a list of AppConfigs to be supplied at runtime

Signed-off-by: Oleg S <97077423+RobotSail@users.noreply.github.com>
---
 .changeset/spotty-cougars-wink.md                        | 6 ------
 packages/backend-app-api/api-report.md                   | 2 +-
 .../backend-app-api/src/config/ObservableConfigProxy.ts  | 2 +-
 packages/backend-app-api/src/config/config.ts            | 8 +++-----
 packages/backend-common/api-report.md                    | 3 +--
 packages/backend-common/src/config.ts                    | 2 +-
 packages/config-loader/src/loader.ts                     | 9 +++------
 7 files changed, 10 insertions(+), 22 deletions(-)
 delete mode 100644 .changeset/spotty-cougars-wink.md

diff --git a/.changeset/spotty-cougars-wink.md b/.changeset/spotty-cougars-wink.md
deleted file mode 100644
index ca3effe724..0000000000
--- a/.changeset/spotty-cougars-wink.md
+++ /dev/null
@@ -1,6 +0,0 @@
----
-'@backstage/backend-app-api': minor
-'@backstage/config-loader': minor
----
-
-Introduces the ability to merge configs and JsonObjects
diff --git a/packages/backend-app-api/api-report.md b/packages/backend-app-api/api-report.md
index 6ef023333b..90b76ffb64 100644
--- a/packages/backend-app-api/api-report.md
+++ b/packages/backend-app-api/api-report.md
@@ -179,7 +179,7 @@ export const lifecycleServiceFactory: () => ServiceFactory<
 export function loadBackendConfig(options: {
   remote?: LoadConfigOptionsRemote;
   argv: string[];
-  additionalConfig?: AppConfig;
+  additionalConfigs?: AppConfig[];
 }): Promise<{
   config: Config;
 }>;
diff --git a/packages/backend-app-api/src/config/ObservableConfigProxy.ts b/packages/backend-app-api/src/config/ObservableConfigProxy.ts
index 8e0ad218e9..dd3334c9a5 100644
--- a/packages/backend-app-api/src/config/ObservableConfigProxy.ts
+++ b/packages/backend-app-api/src/config/ObservableConfigProxy.ts
@@ -16,7 +16,7 @@
 
 import { ConfigService } from '@backstage/backend-plugin-api';
 import { ConfigReader } from '@backstage/config';
-import type { JsonValue } from '@backstage/types';
+import { JsonValue } from '@backstage/types';
 
 export class ObservableConfigProxy implements ConfigService {
   private config: ConfigService = new ConfigReader({});
diff --git a/packages/backend-app-api/src/config/config.ts b/packages/backend-app-api/src/config/config.ts
index 668226e8b2..a2a6f8de9e 100644
--- a/packages/backend-app-api/src/config/config.ts
+++ b/packages/backend-app-api/src/config/config.ts
@@ -71,7 +71,7 @@ export async function createConfigSecretEnumerator(options: {
 export async function loadBackendConfig(options: {
   remote?: LoadConfigOptionsRemote;
   argv: string[];
-  additionalConfig?: AppConfig;
+  additionalConfigs?: AppConfig[];
 }): Promise<{ config: Config }> {
   const args = parseArgs(options.argv);
 
@@ -115,11 +115,9 @@ export async function loadBackendConfig(options: {
     `Loaded config from ${appConfigs.map(c => c.context).join(', ')}`,
   );
 
-  // add the additional config if provided
-  if (options.additionalConfig) {
-    appConfigs.push(options.additionalConfig);
+  if (options.additionalConfigs) {
+    appConfigs.push(...options.additionalConfigs);
   }
-
   config.setConfig(ConfigReader.fromConfigs(appConfigs));
 
   return { config };
diff --git a/packages/backend-common/api-report.md b/packages/backend-common/api-report.md
index a37b5874a3..b1dad254f9 100644
--- a/packages/backend-common/api-report.md
+++ b/packages/backend-common/api-report.md
@@ -6,9 +6,8 @@
 /// <reference types="node" />
 /// <reference types="webpack-env" />
 
+import { AppConfig } from '@backstage/config';
 import { AwsCredentialsManager } from '@backstage/integration-aws-node';
-import type { AppConfig } from '@backstage/config';
-import aws from 'aws-sdk';
 import { AwsS3Integration } from '@backstage/integration';
 import { AzureIntegration } from '@backstage/integration';
 import { BackendFeature } from '@backstage/backend-plugin-api';
diff --git a/packages/backend-common/src/config.ts b/packages/backend-common/src/config.ts
index 47316cfd6e..cc824c47fd 100644
--- a/packages/backend-common/src/config.ts
+++ b/packages/backend-common/src/config.ts
@@ -19,7 +19,7 @@ import {
   loadBackendConfig as newLoadBackendConfig,
 } from '@backstage/backend-app-api';
 import { LoggerService } from '@backstage/backend-plugin-api';
-import type { AppConfig, Config } from '@backstage/config';
+import { AppConfig, Config } from '@backstage/config';
 import { LoadConfigOptionsRemote } from '@backstage/config-loader';
 import { setRootLoggerRedactionList } from './logging/createRootLogger';
 
diff --git a/packages/config-loader/src/loader.ts b/packages/config-loader/src/loader.ts
index 69b0e04b86..f5ce0eb80c 100644
--- a/packages/config-loader/src/loader.ts
+++ b/packages/config-loader/src/loader.ts
@@ -139,11 +139,8 @@ export async function loadConfig(
 
   const env = envFunc ?? (async (name: string) => process.env[name]);
 
-  const loadConfigFiles = async (): Promise<{
-    fileConfigs: AppConfig[];
-    loadedPaths: Set<string>;
-  }> => {
-    const fileConfigs: AppConfig[] = [];
+  const loadConfigFiles = async () => {
+    const fileConfigs = [];
     const loadedPaths = new Set<string>();
 
     for (const configPath of configPaths) {
@@ -179,7 +176,7 @@ export async function loadConfig(
     return { fileConfigs, loadedPaths };
   };
 
-  const loadRemoteConfigFiles = async (): Promise<AppConfig[]> => {
+  const loadRemoteConfigFiles = async () => {
     const configs: AppConfig[] = [];
 
     const readConfigFromUrl = async (url: string) => {

From ffbfcd1ab7ed0ea872f5e13d6b80e5176522004d Mon Sep 17 00:00:00 2001
From: Oleg S <97077423+RobotSail@users.noreply.github.com>
Date: Fri, 10 Mar 2023 09:59:10 -0500
Subject: [PATCH 8/9] merge additional configs with remote configs

Signed-off-by: Oleg S <97077423+RobotSail@users.noreply.github.com>
---
 .changeset/curly-steaks-mate.md               |  1 -
 packages/backend-app-api/src/config/config.ts | 12 ++++++++----
 2 files changed, 8 insertions(+), 5 deletions(-)

diff --git a/.changeset/curly-steaks-mate.md b/.changeset/curly-steaks-mate.md
index 6f32f27a6d..1b41633659 100644
--- a/.changeset/curly-steaks-mate.md
+++ b/.changeset/curly-steaks-mate.md
@@ -1,7 +1,6 @@
 ---
 '@backstage/backend-app-api': minor
 '@backstage/backend-common': minor
-'@backstage/config-loader': minor
 ---
 
 Allow an additionalConfig to be provided to loadBackendConfig that fetches config values during runtime.
diff --git a/packages/backend-app-api/src/config/config.ts b/packages/backend-app-api/src/config/config.ts
index a2a6f8de9e..7367767870 100644
--- a/packages/backend-app-api/src/config/config.ts
+++ b/packages/backend-app-api/src/config/config.ts
@@ -94,8 +94,11 @@ export async function loadBackendConfig(options: {
         console.info(
           `Reloaded config from ${newConfigs.map(c => c.context).join(', ')}`,
         );
-
-        config.setConfig(ConfigReader.fromConfigs(newConfigs));
+        const configsToMerge = [...newConfigs];
+        if (options.additionalConfigs) {
+          configsToMerge.push(...options.additionalConfigs);
+        }
+        config.setConfig(ConfigReader.fromConfigs(configsToMerge));
       },
       stopSignal: new Promise(resolve => {
         if (currentCancelFunc) {
@@ -115,10 +118,11 @@ export async function loadBackendConfig(options: {
     `Loaded config from ${appConfigs.map(c => c.context).join(', ')}`,
   );
 
+  const finalAppConfigs = [...appConfigs];
   if (options.additionalConfigs) {
-    appConfigs.push(...options.additionalConfigs);
+    finalAppConfigs.push(...options.additionalConfigs);
   }
-  config.setConfig(ConfigReader.fromConfigs(appConfigs));
+  config.setConfig(ConfigReader.fromConfigs(finalAppConfigs));
 
   return { config };
 }

From 0d09fec45294466edef8c37e77487a2542ba4d02 Mon Sep 17 00:00:00 2001
From: Patrik Oldsberg <poldsberg@gmail.com>
Date: Thu, 30 Mar 2023 17:05:56 +0200
Subject: [PATCH 9/9] Update .changeset/curly-steaks-mate.md

Signed-off-by: Patrik Oldsberg <poldsberg@gmail.com>
---
 .changeset/curly-steaks-mate.md | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/.changeset/curly-steaks-mate.md b/.changeset/curly-steaks-mate.md
index 1b41633659..93e53c4959 100644
--- a/.changeset/curly-steaks-mate.md
+++ b/.changeset/curly-steaks-mate.md
@@ -1,6 +1,6 @@
 ---
-'@backstage/backend-app-api': minor
-'@backstage/backend-common': minor
+'@backstage/backend-app-api': patch
+'@backstage/backend-common': patch
 ---
 
 Allow an additionalConfig to be provided to loadBackendConfig that fetches config values during runtime.