expose the techdocs-backend plugin using the new system

Signed-off-by: Oleg S <97077423+RobotSail@users.noreply.github.com>

plugins/techdocs-backend/src/index.ts

@@ -37,6 +37,7 @@ export type {
   TechDocsCollatorFactoryOptions,
   TechDocsCollatorOptions,
 } from './search';
+export { techdocsPlugin } from './plugin';
 
 /**
  * @deprecated Use directly from @backstage/plugin-techdocs-node

plugins/techdocs-backend/src/plugin.ts

@@ -0,0 +1,95 @@
+/*
+ * 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 {
+  DockerContainerRunner,
+  loggerToWinstonLogger,
+  cacheToPluginCacheManager,
+} from '@backstage/backend-common';
+import {
+  coreServices,
+  createBackendPlugin,
+} from '@backstage/backend-plugin-api';
+
+import {
+  Preparers,
+  Generators,
+  Publisher,
+} from '@backstage/plugin-techdocs-node';
+import Docker from 'dockerode';
+import { createRouter } from './service';
+
+/**
+ * The TechDocs plugin is responsible for serving and building documentation for any entity.
+ * @public
+ */
+export const techdocsPlugin = createBackendPlugin({
+  pluginId: 'techdocs-backend',
+  register(env) {
+    env.registerInit({
+      deps: {
+        config: coreServices.config,
+        logger: coreServices.logger,
+        urlReader: coreServices.urlReader,
+        http: coreServices.httpRouter,
+        discovery: coreServices.discovery,
+        cache: coreServices.cache,
+      },
+      async init({ config, logger, urlReader, http, discovery, cache }) {
+        const winstonLogger = loggerToWinstonLogger(logger);
+        // Preparers are responsible for fetching source files for documentation.
+        const preparers = await Preparers.fromConfig(config, {
+          reader: urlReader,
+          logger: winstonLogger,
+        });
+
+        // Docker client (conditionally) used by the generators, based on techdocs.generators config.
+        const dockerClient = new Docker();
+        const containerRunner = new DockerContainerRunner({ dockerClient });
+
+        // Generators are used for generating documentation sites.
+        const generators = await Generators.fromConfig(config, {
+          logger: winstonLogger,
+          containerRunner,
+        });
+
+        // Publisher is used for
+        // 1. Publishing generated files to storage
+        // 2. Fetching files from storage and passing them to TechDocs frontend.
+        const publisher = await Publisher.fromConfig(config, {
+          logger: winstonLogger,
+          discovery: discovery,
+        });
+
+        // checks if the publisher is working and logs the result
+        await publisher.getReadiness();
+
+        const cacheManager = cacheToPluginCacheManager(cache);
+        http.use(
+          await createRouter({
+            logger: winstonLogger,
+            cache: cacheManager,
+            preparers,
+            generators,
+            publisher,
+            config,
+            discovery,
+          }),
+        );
+      },
+    });
+  },
+});