frontend-*-api: introduce ExtensionBoundary and pass source to extension factories

Co-authored-by: Fredrik Adelöw <freben@gmail.com>
Co-authored-by: Johan Haals <johan.haals@gmail.com>
Co-authored-by: Camila Belo <camilaibs@gmail.com>
Co-authored-by: Philipp Hugenroth <philipph@spotify.com>
Signed-off-by: Patrik Oldsberg <poldsberg@gmail.com>

packages/frontend-app-api/src/createApp.tsx

@@ -41,13 +41,11 @@ export function createApp(options: { plugins: BackstagePlugin[] }): {
 
   // pull in default extension instance from discovered packages
   // apply config to adjust default extension instances and add more
-  const extensionParams = mergeExtensionParameters(
-    [
-      ...options.plugins.flatMap(plugin => plugin.extensions),
-      ...builtinExtensions,
-    ],
-    readAppExtensionParameters(appConfig),
-  );
+  const extensionParams = mergeExtensionParameters({
+    sources: options.plugins,
+    builtinExtensions,
+    parameters: readAppExtensionParameters(appConfig),
+  });
 
   // TODO: validate the config of all extension instances
   // We do it at this point to ensure that merging (if any) of config has already happened
@@ -96,6 +94,7 @@ export function createApp(options: { plugins: BackstagePlugin[] }): {
 
     return createExtensionInstance({
       extension: instanceParams.extension,
+      source: instanceParams.source,
       config: instanceParams.config,
       attachments,
     });

packages/frontend-app-api/src/createExtensionInstance.ts

@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-import { Extension } from '@backstage/frontend-plugin-api';
+import { BackstagePlugin, Extension } from '@backstage/frontend-plugin-api';
 import mapValues from 'lodash/mapValues';
 
 /** @internal */
@@ -28,9 +28,10 @@ export interface ExtensionInstance {
 export function createExtensionInstance(options: {
   extension: Extension<unknown>;
   config: unknown;
+  source?: BackstagePlugin;
   attachments: Record<string, ExtensionInstance[]>;
 }): ExtensionInstance {
-  const { extension, config, attachments } = options;
+  const { extension, config, source, attachments } = options;
   const extensionData = new Map<string, unknown>();
 
   let parsedConfig: unknown;
@@ -44,6 +45,7 @@ export function createExtensionInstance(options: {
 
   try {
     extension.factory({
+      source,
       config: parsedConfig,
       bind: mapValues(extension.output, ref => {
         return (value: unknown) => extensionData.set(ref.id, value);

packages/frontend-app-api/src/wiring/parameters.test.ts

@@ -15,7 +15,7 @@
  */
 
 import { ConfigReader } from '@backstage/config';
-import { Extension } from '@backstage/frontend-plugin-api';
+import { createPlugin, Extension } from '@backstage/frontend-plugin-api';
 import { JsonValue } from '@backstage/types';
 import {
   expandShorthandExtensionParameters,
@@ -33,15 +33,25 @@ function makeExt(id: string, status: 'disabled' | 'enabled' = 'enabled') {
 
 describe('mergeExtensionParameters', () => {
   it('should filter out disabled extension instances', () => {
-    expect(mergeExtensionParameters([makeExt('a', 'disabled')], [])).toEqual(
-      [],
-    );
+    expect(
+      mergeExtensionParameters({
+        sources: [],
+        builtinExtensions: [makeExt('a', 'disabled')],
+        parameters: [],
+      }),
+    ).toEqual([]);
   });
 
   it('should pass through extension instances', () => {
     const a = makeExt('a');
     const b = makeExt('b');
-    expect(mergeExtensionParameters([a, b], [])).toEqual([
+    expect(
+      mergeExtensionParameters({
+        sources: [],
+        builtinExtensions: [a, b],
+        parameters: [],
+      }),
+    ).toEqual([
       { extension: a, at: 'root' },
       { extension: b, at: 'root' },
     ]);
@@ -50,18 +60,20 @@ describe('mergeExtensionParameters', () => {
   it('should override attachment points', () => {
     const a = makeExt('a');
     const b = makeExt('b');
+    const pluginA = createPlugin({ id: 'test', extensions: [a] });
     expect(
-      mergeExtensionParameters(
-        [a, b],
-        [
+      mergeExtensionParameters({
+        sources: [pluginA],
+        builtinExtensions: [b],
+        parameters: [
           {
             id: 'b',
             at: 'derp',
           },
         ],
-      ),
+      }),
     ).toEqual([
-      { extension: a, at: 'root' },
+      { extension: a, at: 'root', source: pluginA },
       { extension: b, at: 'derp' },
     ]);
   });
@@ -69,10 +81,12 @@ describe('mergeExtensionParameters', () => {
   it('should fully override configuration and duplicate', () => {
     const a = makeExt('a');
     const b = makeExt('b');
+    const plugin = createPlugin({ id: 'test', extensions: [a, b] });
     expect(
-      mergeExtensionParameters(
-        [a, b],
-        [
+      mergeExtensionParameters({
+        sources: [plugin],
+        builtinExtensions: [],
+        parameters: [
           {
             id: 'a',
             config: { foo: { bar: 1 } },
@@ -86,10 +100,10 @@ describe('mergeExtensionParameters', () => {
             config: { foo: { qux: 3 } },
           },
         ],
-      ),
+      }),
     ).toEqual([
-      { extension: a, at: 'root', config: { foo: { bar: 1 } } },
-      { extension: b, at: 'root', config: { foo: { qux: 3 } } },
+      { extension: a, at: 'root', source: plugin, config: { foo: { bar: 1 } } },
+      { extension: b, at: 'root', source: plugin, config: { foo: { qux: 3 } } },
     ]);
   });
 
@@ -97,9 +111,10 @@ describe('mergeExtensionParameters', () => {
     const a = makeExt('a', 'disabled');
     const b = makeExt('b', 'disabled');
     expect(
-      mergeExtensionParameters(
-        [a, b],
-        [
+      mergeExtensionParameters({
+        sources: [createPlugin({ id: 'empty', extensions: [] })],
+        builtinExtensions: [a, b],
+        parameters: [
           {
             id: 'b',
             disabled: false,
@@ -109,7 +124,7 @@ describe('mergeExtensionParameters', () => {
             disabled: false,
           },
         ],
-      ),
+      }),
     ).toEqual([
       { extension: b, at: 'root' },
       { extension: a, at: 'root' },

packages/frontend-app-api/src/wiring/parameters.ts

@@ -15,7 +15,7 @@
  */
 
 import { Config } from '@backstage/config';
-import { Extension } from '@backstage/frontend-plugin-api';
+import { BackstagePlugin, Extension } from '@backstage/frontend-plugin-api';
 import { JsonValue } from '@backstage/types';
 
 export interface ExtensionParameters {
@@ -183,23 +183,41 @@ export function expandShorthandExtensionParameters(
 
 export interface ExtensionInstanceParameters {
   extension: Extension<unknown>;
+  source?: BackstagePlugin;
   at: string;
   config?: unknown;
 }
 
 /** @internal */
-export function mergeExtensionParameters(
-  base: Extension<unknown>[],
-  parameters: Array<ExtensionParameters>,
-): ExtensionInstanceParameters[] {
-  const overrides = base.map(extension => ({
-    extension,
-    params: {
-      at: extension.at,
-      disabled: extension.disabled,
-      config: undefined as unknown,
-    },
-  }));
+export function mergeExtensionParameters(options: {
+  sources: BackstagePlugin[];
+  builtinExtensions: Extension<unknown>[];
+  parameters: Array<ExtensionParameters>;
+}): ExtensionInstanceParameters[] {
+  const { sources, builtinExtensions, parameters } = options;
+
+  const overrides = [
+    ...sources.flatMap(plugin =>
+      plugin.extensions.map(extension => ({
+        extension,
+        params: {
+          source: plugin,
+          at: extension.at,
+          disabled: extension.disabled,
+          config: undefined as unknown,
+        },
+      })),
+    ),
+    ...builtinExtensions.map(extension => ({
+      extension,
+      params: {
+        source: undefined,
+        at: extension.at,
+        disabled: extension.disabled,
+        config: undefined as unknown,
+      },
+    })),
+  ];
 
   for (const overrideParam of parameters) {
     const existingIndex = overrides.findIndex(
@@ -234,6 +252,7 @@ export function mergeExtensionParameters(
     .map(param => ({
       extension: param.extension,
       at: param.params.at,
+      source: param.params.source,
       config: param.params.config,
     }));
 }