plugin(jenkins-backend): Add extension point

Add an extension point to the `jenkins-backend` plugin so a custom
JenkinsInforProvider can be used.

Fixes backstage#2926

Signed-off-by: Luiz Carvalho <lucarval@redhat.com>

workspaces/jenkins/.changeset/tasty-wasps-behave.md

@@ -0,0 +1,5 @@
+---
+'@backstage-community/plugin-jenkins-backend': patch
+---
+
+Add ExtensionPoint to allow usage of a custom JenkinsInfoProvider

workspaces/jenkins/plugins/jenkins-backend/src/extensions.ts

@@ -0,0 +1,35 @@
+/*
+ * Copyright 2025 The Backstage Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import { createExtensionPoint } from '@backstage/backend-plugin-api';
+import { JenkinsInfoProvider } from './service';
+
+/**
+ * @public
+ */
+export interface JenkinsInfoProviderExtensionPoint {
+  setInfoProvider(infoProvider: JenkinsInfoProvider): void;
+}
+
+/**
+ * Extension point that allows a different JenkinsInfoProvider to be used.
+ *
+ * @public
+ */
+export const jenkinsInfoProviderExtensionPoint =
+  createExtensionPoint<JenkinsInfoProviderExtensionPoint>({
+    id: 'jenkins.info-provider',
+  });

workspaces/jenkins/plugins/jenkins-backend/src/plugin.ts

@@ -18,9 +18,13 @@ import {
   coreServices,
   createBackendPlugin,
 } from '@backstage/backend-plugin-api';
-import { DefaultJenkinsInfoProvider } from './service/jenkinsInfoProvider';
+import {
+  DefaultJenkinsInfoProvider,
+  JenkinsInfoProvider,
+} from './service/jenkinsInfoProvider';
 import { catalogServiceRef } from '@backstage/plugin-catalog-node/alpha';
 import { JenkinsBuilder } from './service/JenkinsBuilder';
+import { jenkinsInfoProviderExtensionPoint } from './extensions';
 
 /**
  * Jenkins backend plugin
@@ -30,6 +34,17 @@ import { JenkinsBuilder } from './service/JenkinsBuilder';
 export const jenkinsPlugin = createBackendPlugin({
   pluginId: 'jenkins',
   register(env) {
+    let jenkinsInfoProvider: JenkinsInfoProvider | undefined;
+
+    env.registerExtensionPoint(jenkinsInfoProviderExtensionPoint, {
+      setInfoProvider(customInfoProvider: JenkinsInfoProvider) {
+        if (jenkinsInfoProvider) {
+          throw new Error('The JenkinsInfoProvider has been already set');
+        }
+        jenkinsInfoProvider = customInfoProvider;
+      },
+    });
+
     env.registerInit({
       deps: {
         logger: coreServices.logger,
@@ -51,14 +66,17 @@ export const jenkinsPlugin = createBackendPlugin({
         auth,
         httpAuth,
       }) {
-        const jenkinsInfoProvider = DefaultJenkinsInfoProvider.fromConfig({
-          auth,
-          httpAuth,
-          config,
-          catalog: catalogClient,
-          discovery,
-          logger,
-        });
+        jenkinsInfoProvider =
+          jenkinsInfoProvider ??
+          DefaultJenkinsInfoProvider.fromConfig({
+            auth,
+            httpAuth,
+            config,
+            catalog: catalogClient,
+            discovery,
+            logger,
+          });
+
         const builder = JenkinsBuilder.createBuilder({
           /**
            * Logger for logging purposes