implement some of the trivial backend plugins

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

plugins/periskop-backend/api-report.md

@@ -3,6 +3,7 @@
 > Do not edit this file. It is a report generated by [API Extractor](https://api-extractor.com/).
 
 ```ts
+import { BackendFeature } from '@backstage/backend-plugin-api';
 import { Config } from '@backstage/config';
 import express from 'express';
 import { Logger } from 'winston';
@@ -10,6 +11,9 @@ import { Logger } from 'winston';
 // @public (undocumented)
 export function createRouter(options: RouterOptions): Promise<express.Router>;
 
+// @alpha
+export const periskopPlugin: () => BackendFeature;
+
 // @public (undocumented)
 export interface RouterOptions {
   // (undocumented)

plugins/periskop-backend/package.json

@@ -11,11 +11,12 @@
   "publishConfig": {
     "access": "public",
     "main": "dist/index.cjs.js",
-    "types": "dist/index.d.ts"
+    "types": "dist/index.d.ts",
+    "alphaTypes": "dist/index.alpha.d.ts"
   },
   "scripts": {
     "start": "backstage-cli package start",
-    "build": "backstage-cli package build",
+    "build": "backstage-cli package build --experimental-type-build",
     "lint": "backstage-cli package lint",
     "test": "backstage-cli package test",
     "prepack": "backstage-cli package prepack",
@@ -24,6 +25,7 @@
   },
   "dependencies": {
     "@backstage/backend-common": "workspace:^",
+    "@backstage/backend-plugin-api": "workspace:^",
     "@backstage/config": "workspace:^",
     "@types/express": "*",
     "express": "^4.17.1",
@@ -39,6 +41,7 @@
     "supertest": "^6.1.6"
   },
   "files": [
-    "dist"
+    "dist",
+    "alpha"
   ]
 }

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) }),
+        );
+      },
+    });
+  },
+});