implement some of the trivial backend plugins

Signed-off-by: Fredrik Adelöw <freben@gmail.com>

plugins/proxy-backend/src/index.ts

@@ -21,3 +21,4 @@
  */
 
 export * from './service';
+export { proxyPlugin } from './plugin';

plugins/proxy-backend/src/plugin.ts

@@ -0,0 +1,53 @@
+/*
+ * Copyright 2023 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 { loggerToWinstonLogger } from '@backstage/backend-common';
+import {
+  createBackendPlugin,
+  coreServices,
+} from '@backstage/backend-plugin-api';
+import { createRouter } from './service/router';
+
+/**
+ * The proxy backend plugin.
+ *
+ * @alpha
+ */
+export const proxyPlugin = createBackendPlugin(
+  (options?: { skipInvalidProxies?: boolean }) => ({
+    id: 'proxy',
+    register(env) {
+      env.registerInit({
+        deps: {
+          config: coreServices.config,
+          discovery: coreServices.discovery,
+          logger: coreServices.logger,
+          httpRouter: coreServices.httpRouter,
+        },
+        async init({ config, discovery, logger, httpRouter }) {
+          httpRouter.use(
+            await createRouter({
+              config,
+              discovery,
+              logger: loggerToWinstonLogger(logger),
+              skipInvalidProxies: options?.skipInvalidProxies,
+            }),
+          );
+        },
+      });
+    },
+  }),
+);