feat(extension-metrics): add metrics extension for prometheus

extensions/metrics/.npmrc

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+package-lock=true

extensions/metrics/LICENSE

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+Copyright (c) IBM Corp. 2019. All Rights Reserved.
+Node module: @loopback/extension-metrics
+This project is licensed under the MIT License, full text below.
+
+--------
+
+MIT license
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in
+all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+THE SOFTWARE.

extensions/metrics/README.md

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+# @loopback/extension-metrics
+
+This module contains a component to report metrics for
+[Prometheus](https://prometheus.io/).
+
+## Installation
+
+```sh
+npm install --save @loopback/extension-metrics
+```
+
+## Basic use
+
+The component should be loaded in the constructor of your custom Application
+class.
+
+Start by importing the component class:
+
+```ts
+import {MetricsComponent} from '@loopback/extension-metrics';
+```
+
+In the constructor, add the component to your application:
+
+```ts
+this.component(MetricsComponent);
+```
+
+By default, Metrics route is mounted at `/metrics`. This path can be customized
+via Metrics configuration as follows:
+
+```ts
+this.bind(MetricsBindings.CONFIG).to({
+  endpoint: {
+    basePath: '/metrics',
+  },
+  defaultMetrics: {
+    options: {
+      timeout: 5000,
+    },
+  },
+});
+```
+
+## Try it out
+
+```sh
+npm run demo
+```
+
+Open http://localhost:9090 to load Prometheus web UI.
+
+http://localhost:3000/metrics returns metrics in plain text format.
+
+## Contributions
+
+- [Guidelines](https://github.com/strongloop/loopback-next/blob/master/docs/CONTRIBUTING.md)
+- [Join the team](https://github.com/strongloop/loopback-next/issues/110)
+
+## Tests
+
+Run `npm test` from the root folder.
+
+## Contributors
+
+See
+[all contributors](https://github.com/strongloop/loopback-next/graphs/contributors).
+
+## License
+
+MIT

extensions/metrics/index.d.ts

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+// Copyright IBM Corp. 2018. All Rights Reserved.
+// Node module: @loopback/rest-explorer
+// This file is licensed under the MIT License.
+// License text available at https://opensource.org/licenses/MIT
+
+export * from './dist';

extensions/metrics/index.js

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+// Copyright IBM Corp. 2019. All Rights Reserved.
+// Node module: @loopback/extension-metrics
+// This file is licensed under the MIT License.
+// License text available at https://opensource.org/licenses/MIT
+
+module.exports = require('./dist');

extensions/metrics/index.ts

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+// Copyright IBM Corp. 2019. All Rights Reserved.
+// Node module: @loopback/extension-metrics
+// This file is licensed under the MIT License.
+// License text available at https://opensource.org/licenses/MIT
+
+// DO NOT EDIT THIS FILE
+// Add any additional (re)exports to src/index.ts instead.
+export * from './src';

extensions/metrics/package.json

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+{
+  "name": "@loopback/extension-metrics",
+  "version": "1.0.0",
+  "description": "LoopBack Metrics",
+  "engines": {
+    "node": ">=8.9"
+  },
+  "scripts": {
+    "build": "lb-tsc",
+    "clean": "lb-clean loopback-extension-metrics*.tgz dist tsconfig.build.tsbuildinfo package",
+    "pretest": "npm run build",
+    "test": "lb-mocha \"dist/__tests__/**/*.js\"",
+    "verify": "npm pack && tar xf loopback-extension-metrics*.tgz && tree package && npm run clean",
+    "demo": "./src/__examples__/demo.sh"
+  },
+  "author": "IBM Corp.",
+  "copyright.owner": "IBM Corp.",
+  "license": "MIT",
+  "dependencies": {
+    "@loopback/context": "^1.20.2",
+    "@loopback/core": "^1.8.5",
+    "@loopback/rest": "^1.16.3",
+    "prom-client": "^11.5.3"
+  },
+  "devDependencies": {
+    "@loopback/build": "^2.0.3",
+    "@loopback/eslint-config": "^2.0.0",
+    "@loopback/testlab": "^1.6.3",
+    "@types/node": "^10.14.12"
+  },
+  "keywords": [
+    "LoopBack",
+    "Prometheus",
+    "Metrics"
+  ],
+  "files": [
+    "README.md",
+    "index.js",
+    "index.d.ts",
+    "dist",
+    "src",
+    "!*/__tests__",
+    "templates"
+  ],
+  "publishConfig": {
+    "access": "public"
+  },
+  "repository": {
+    "type": "git",
+    "url": "https://github.com/strongloop/loopback-next.git"
+  }
+}

extensions/metrics/src/__examples__/demo.sh

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+#!/bin/bash
+
+# This script runs prometheus to scape and visulize metrics collected for the
+# example LoopBack 4 application.
+
+DIR=`dirname $0`
+CWD=`pwd`
+CONFIG=$CWD/$DIR/prometheus.yml
+
+PROM_CONTAINER_NAME="prometheus_lb4_demo"
+docker rm -f $PROM_CONTAINER_NAME
+docker pull prom/prometheus:latest
+docker run --name $PROM_CONTAINER_NAME -p 9090:9090 -v $CONFIG:/etc/prometheus/prometheus.yml -d prom/prometheus
+
+echo Prometheus is running at http://localhost:9090.
+
+pushd $DIR/../.. >/dev/null
+npm run build
+node ./dist/__examples__/metrics
+popd
+

extensions/metrics/src/__examples__/metrics.ts

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+// Copyright IBM Corp. 2019. All Rights Reserved.
+// Node module: @loopback/rest-explorer
+// This file is licensed under the MIT License.
+// License text available at https://opensource.org/licenses/MIT
+
+import {RestApplication} from '@loopback/rest';
+import {MetricsComponent} from '../';
+
+async function main() {
+  const app = new RestApplication({rest: {port: 3000}});
+  app.component(MetricsComponent);
+  await app.start();
+  console.log(app.restServer.url);
+}
+
+main().catch(err => {
+  console.error(err);
+  process.exit(1);
+});

extensions/metrics/src/__examples__/prometheus.yml

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+# my global config
+global:
+  scrape_interval:     15s # Set the scrape interval to every 15 seconds. Default is every 1 minute.
+  evaluation_interval: 15s # Evaluate rules every 15 seconds. The default is every 1 minute.
+  # scrape_timeout is set to the global default (10s).
+
+# Alertmanager configuration
+alerting:
+  alertmanagers:
+  - static_configs:
+    - targets:
+      # - alertmanager:9093
+
+# Load rules once and periodically evaluate them according to the global 'evaluation_interval'.
+rule_files:
+  # - "first_rules.yml"
+  # - "second_rules.yml"
+
+# A scrape configuration containing exactly one endpoint to scrape:
+# Here it's Prometheus itself.
+scrape_configs:
+  # The job name is added as a label `job=<job_name>` to any timeseries scraped from this config.
+  - job_name: 'prometheus'
+
+    # metrics_path defaults to '/metrics'
+    # scheme defaults to 'http'.
+
+    static_configs:
+    - targets: ['host.docker.internal:3000']

extensions/metrics/src/__tests__/acceptance/metrics.acceptance.ts

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+// Copyright IBM Corp. 2019. All Rights Reserved.
+// Node module: @loopback/rest-explorer
+// This file is licensed under the MIT License.
+// License text available at https://opensource.org/licenses/MIT
+
+import {RestApplication, RestServerConfig} from '@loopback/rest';
+import {
+  Client,
+  createRestAppClient,
+  expect,
+  givenHttpServerConfig,
+} from '@loopback/testlab';
+import {MetricsComponent} from '../..';
+import {MetricsBindings} from '../../keys';
+import {MetricsOptions} from '../../types';
+
+describe('Metrics (acceptance)', () => {
+  let app: RestApplication;
+  let request: Client;
+
+  afterEach(async () => {
+    if (app) await app.stop();
+    (app as unknown) = undefined;
+  });
+
+  context('with default config', () => {
+    beforeEach(async () => {
+      app = givenRestApplication();
+      app.component(MetricsComponent);
+      await app.start();
+      request = createRestAppClient(app);
+    });
+
+    it('exposes metrics at "/metrics/"', async () => {
+      const res = await request
+        .get('/metrics')
+        .expect(200)
+        .expect('content-type', /text/);
+      expect(res.text).to.match(/# TYPE/);
+      expect(res.text).to.match(/# HELP/);
+    });
+  });
+
+  context('with custom defaultMetrics', () => {
+    it('honors prefix', async () => {
+      await givenAppWithCustomConfig({
+        defaultMetrics: {
+          options: {
+            // `-` is not allowed
+            prefix: 'myapp_',
+          },
+        },
+      });
+      await request
+        .get('/metrics')
+        .expect(200)
+        .expect('content-type', /text/);
+    });
+  });
+
+  context('with custom endpoint basePath', () => {
+    it('honors prefix', async () => {
+      await givenAppWithCustomConfig({
+        endpoint: {
+          basePath: '/internal/metrics',
+        },
+      });
+      await request
+        .get('/internal/metrics')
+        .expect(200)
+        .expect('content-type', /text/);
+      await request.get('/metrics').expect(404);
+    });
+  });
+
+  context('with defaultMetrics disabled', () => {
+    it('does not emit default metrics', async () => {
+      await givenAppWithCustomConfig({
+        defaultMetrics: {
+          disabled: true,
+        },
+      });
+      const res = await request
+        .get('/metrics')
+        .expect(200)
+        .expect('content-type', /text/);
+      expect(res.text).to.not.match(
+        /# TYPE process_cpu_user_seconds_total counter/,
+      );
+    });
+  });
+
+  async function givenAppWithCustomConfig(config: MetricsOptions) {
+    app = givenRestApplication();
+    app.bind(MetricsBindings.CONFIG).to(config);
+    app.component(MetricsComponent);
+    await app.start();
+    request = createRestAppClient(app);
+  }
+
+  function givenRestApplication(config?: RestServerConfig) {
+    const rest = Object.assign({}, givenHttpServerConfig(), config);
+    return new RestApplication({rest});
+  }
+});

extensions/metrics/src/controllers/index.ts

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+// Copyright IBM Corp. 2019. All Rights Reserved.
+// Node module: @loopback/extension-metrics
+// This file is licensed under the MIT License.
+// License text available at https://opensource.org/licenses/MIT
+
+export * from './metrics.controller';