Kubernetes plugins boilerplate (#2559)

* Kubernetes plugins boilerplate

* pr feedback; check for k8s annotation

plugins/kubernetes-backend/.eslintrc.js

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+module.exports = {
+  extends: [require.resolve('@backstage/cli/config/eslint.backend')],
+};

plugins/kubernetes-backend/README.md

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+# Kubernetes Backend
+
+WORK IN PROGRESS
+
+This is the backend part of the Kubernetes plugin.
+
+It responds to Kubernetes requests from the frontend.
+
+## Links
+
+- [The Backstage homepage](https://backstage.io)

plugins/kubernetes-backend/package.json

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+{
+  "name": "@backstage/plugin-kubernetes-backend",
+  "version": "0.1.1-alpha.22",
+  "main": "src/index.ts",
+  "types": "src/index.ts",
+  "license": "Apache-2.0",
+  "private": false,
+  "publishConfig": {
+    "access": "public",
+    "main": "dist/index.cjs.js",
+    "types": "dist/index.d.ts"
+  },
+  "scripts": {
+    "start": "backstage-cli backend:dev",
+    "build": "backstage-cli backend:build",
+    "lint": "backstage-cli lint",
+    "test": "backstage-cli test",
+    "prepack": "backstage-cli prepack",
+    "postpack": "backstage-cli postpack",
+    "clean": "backstage-cli clean"
+  },
+  "dependencies": {
+    "@backstage/backend-common": "^0.1.1-alpha.22",
+    "@types/express": "^4.17.6",
+    "compression": "^1.7.4",
+    "cors": "^2.8.5",
+    "express": "^4.17.1",
+    "express-promise-router": "^3.0.3",
+    "fs-extra": "^9.0.0",
+    "helmet": "^4.0.0",
+    "morgan": "^1.10.0",
+    "winston": "^3.2.1",
+    "yn": "^4.0.0"
+  },
+  "devDependencies": {
+    "@backstage/cli": "^0.1.1-alpha.22",
+    "jest-fetch-mock": "^3.0.3"
+  },
+  "files": [
+    "dist"
+  ]
+}

plugins/kubernetes-backend/src/index.test.ts

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+/*
+ * Copyright 2020 Spotify AB
+ *
+ * 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 '@backstage/backend-common';
+
+describe('test', () => {
+  it('unbreaks the test runner', () => {
+    expect(true).toBeTruthy();
+  });
+});

plugins/kubernetes-backend/src/index.ts

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+/*
+ * Copyright 2020 Spotify AB
+ *
+ * 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.
+ */
+
+export * from './service/router';

plugins/kubernetes-backend/src/run.ts

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+/*
+ * Copyright 2020 Spotify AB
+ *
+ * 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 yn from 'yn';
+import { getRootLogger } from '@backstage/backend-common';
+import { startStandaloneServer } from './service/standaloneServer';
+
+const port = process.env.PLUGIN_PORT ? Number(process.env.PLUGIN_PORT) : 3004;
+const enableCors = yn(process.env.PLUGIN_CORS, { default: false });
+const logger = getRootLogger();
+
+startStandaloneServer({ port, enableCors, logger }).catch(err => {
+  logger.error(err);
+  process.exit(1);
+});
+
+process.on('SIGINT', () => {
+  logger.info('CTRL+C pressed; exiting.');
+  process.exit(0);
+});

plugins/kubernetes-backend/src/service/router.ts

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+/*
+ * Copyright 2020 Spotify AB
+ *
+ * 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 express from 'express';
+import Router from 'express-promise-router';
+import { Logger } from 'winston';
+
+export interface RouterOptions {
+  logger: Logger;
+}
+
+const makeRouter = (logger: Logger): express.Router => {
+  const router = Router();
+  router.use(express.json());
+
+  router.get('/services/:serviceId', async (req, res) => {
+    const serviceId = req.params.serviceId;
+    logger.info(`HERE ${serviceId}`);
+    res.send({ serviceId });
+  });
+
+  return router;
+};
+
+export async function createRouter(
+  options: RouterOptions,
+): Promise<express.Router> {
+  const logger = options.logger;
+
+  logger.info('Initializing Kubernetes backend');
+  return makeRouter(logger);
+}

plugins/kubernetes-backend/src/service/standaloneApplication.ts

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+/*
+ * Copyright 2020 Spotify AB
+ *
+ * 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 {
+  errorHandler,
+  notFoundHandler,
+  requestLoggingHandler,
+} from '@backstage/backend-common';
+import compression from 'compression';
+import cors from 'cors';
+import express from 'express';
+import helmet from 'helmet';
+import { Logger } from 'winston';
+import { createRouter } from './router';
+
+export interface ApplicationOptions {
+  enableCors: boolean;
+  logger: Logger;
+}
+
+export async function createStandaloneApplication(
+  options: ApplicationOptions,
+): Promise<express.Application> {
+  const { enableCors, logger } = options;
+  const app = express();
+
+  app.use(helmet());
+  if (enableCors) {
+    app.use(cors());
+  }
+  app.use(compression());
+  app.use(express.json());
+  app.use(requestLoggingHandler());
+  app.use('/', await createRouter({ logger }));
+  app.use(notFoundHandler());
+  app.use(errorHandler());
+
+  return app;
+}

plugins/kubernetes-backend/src/service/standaloneServer.ts

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+/*
+ * Copyright 2020 Spotify AB
+ *
+ * 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 { Server } from 'http';
+import { Logger } from 'winston';
+import { createStandaloneApplication } from './standaloneApplication';
+
+export interface ServerOptions {
+  port: number;
+  enableCors: boolean;
+  logger: Logger;
+}
+
+export async function startStandaloneServer(
+  options: ServerOptions,
+): Promise<Server> {
+  const logger = options.logger.child({ service: 'kubernetes-backend' });
+
+  logger.debug('Creating application...');
+  const app = await createStandaloneApplication({
+    enableCors: options.enableCors,
+    logger,
+  });
+
+  logger.debug('Starting application server...');
+  return await new Promise((resolve, reject) => {
+    const server = app.listen(options.port, (err?: Error) => {
+      if (err) {
+        reject(err);
+        return;
+      }
+
+      logger.info(`Listening on port ${options.port}`);
+      resolve(server);
+    });
+  });
+}

plugins/kubernetes-backend/src/setupTests.ts

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+/*
+ * Copyright 2020 Spotify AB
+ *
+ * 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.
+ */
+
+require('jest-fetch-mock').enableMocks();
+
+export {};