implement some of the trivial backend plugins

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

plugins/periskop-backend/src/index.ts

@@ -15,3 +15,4 @@
  */
 
 export * from './service/router';
+export { periskopPlugin } from './plugin';

plugins/periskop-backend/src/plugin.ts

@@ -0,0 +1,45 @@
+/*
+ * 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 {
+  coreServices,
+  createBackendPlugin,
+} from '@backstage/backend-plugin-api';
+import { createRouter } from './service/router';
+
+/**
+ * The Periskop backend plugin.
+ *
+ * @alpha
+ */
+export const periskopPlugin = createBackendPlugin({
+  id: 'periskop',
+  register(env) {
+    env.registerInit({
+      deps: {
+        config: coreServices.config,
+        logger: coreServices.logger,
+        httpRouter: coreServices.httpRouter,
+      },
+      async init({ config, logger, httpRouter }) {
+        httpRouter.use(
+          await createRouter({ config, logger: loggerToWinstonLogger(logger) }),
+        );
+      },
+    });
+  },
+});