Add Nomad Backend plugin

Signed-off-by: josh <josh.timmons@hashicorp.com>

plugins/nomad-backend/src/index.ts

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+/*
+ * 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.
+ */
+export * from './service/router';

plugins/nomad-backend/src/run.ts

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+/*
+ * 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 { getRootLogger } from '@backstage/backend-common';
+import yn from 'yn';
+import { startStandaloneServer } from './service/standaloneServer';
+
+const port = process.env.PLUGIN_PORT ? Number(process.env.PLUGIN_PORT) : 7007;
+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/nomad-backend/src/service/router.test.ts

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+/*
+ * 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 { getVoidLogger } from '@backstage/backend-common';
+import express from 'express';
+import request from 'supertest';
+
+import { createRouter } from './router';
+
+describe('createRouter', () => {
+  let app: express.Express;
+
+  beforeAll(async () => {
+    const router = await createRouter({
+      logger: getVoidLogger(),
+    });
+    app = express().use(router);
+  });
+
+  beforeEach(() => {
+    jest.resetAllMocks();
+  });
+
+  describe('GET /health', () => {
+    it('returns ok', async () => {
+      const response = await request(app).get('/health');
+
+      expect(response.status).toEqual(200);
+      expect(response.body).toEqual({ status: 'ok' });
+    });
+  });
+});

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

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+/*
+ * 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 { errorHandler, requestLoggingHandler } from '@backstage/backend-common';
+import { Config } from '@backstage/config';
+import { InputError } from '@backstage/errors';
+import express from 'express';
+import Router from 'express-promise-router';
+import { Logger } from 'winston';
+
+export interface RouterOptions {
+  logger: Logger;
+  config: Config;
+}
+
+export async function createRouter(
+  options: RouterOptions,
+): Promise<express.Router> {
+  const { config, logger } = options;
+
+  const router = Router();
+  router.use(express.json());
+
+  router.get('/health', (_, response) => {
+    logger.info('PONG!');
+    response.json({ status: 'ok' });
+  });
+
+  router.get('/v1/allocations', async (req, resp) => {
+    const addr = config.getString('nomad.addr');
+    const token = config.getOptionalString('nomad.token');
+
+    const namespace = (req.query.namespace as string) ?? '';
+    if (!namespace || namespace === '') {
+      throw new InputError(`Missing "namespace" query parameter`);
+    }
+
+    const filter = (req.query.filter as string) ?? '';
+    if (!filter || filter === '') {
+      throw new InputError(`Missing "filter" query parameter`);
+    }
+
+    logger.debug(
+      `/v1/allocations request headers: namespace=${namespace} filter=${filter}`,
+    );
+    const allocationsResp = await fetch(
+      `${addr}/v1/allocations?namespace=${encodeURIComponent(
+        namespace,
+      )}&filter=${encodeURIComponent(filter)}`,
+      {
+        method: 'GET',
+        headers: {
+          Accept: 'application/json',
+          'X-Nomad-Token': token || '',
+        },
+      },
+    );
+
+    const allocationsBody = await allocationsResp.json();
+    logger.debug(`/v1/allocations response: ${allocationsBody}`);
+
+    resp.json(allocationsBody);
+  });
+
+  router.use(requestLoggingHandler());
+  router.use(errorHandler());
+  return router;
+}

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

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+/*
+ * 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 { createServiceBuilder } from '@backstage/backend-common';
+import { Server } from 'http';
+import { Logger } from 'winston';
+import { createRouter } from './router';
+import { Config } from '@backstage/config';
+
+export interface ServerOptions {
+  config: Config;
+  enableCors: boolean;
+  logger: Logger;
+  port: number;
+}
+
+export async function startStandaloneServer(
+  options: ServerOptions,
+): Promise<Server> {
+  const logger = options.logger.child({ service: 'nomad' });
+  logger.debug('Starting application server...');
+  const router = await createRouter({
+    logger,
+    config: options.config,
+  });
+
+  let service = createServiceBuilder(module)
+    .setPort(options.port)
+    .addRouter('/nomad', router);
+  if (options.enableCors) {
+    service = service.enableCors({ origin: 'http://localhost:3000' });
+  }
+
+  return await service.start().catch(err => {
+    logger.error(err);
+    process.exit(1);
+  });
+}
+
+module.hot?.accept();

plugins/nomad-backend/src/setupTests.ts

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+/*
+ * 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.
+ */
+export {};