Server Metrics with Prometheus

Implementation use internal eventBus to enable loose counting in the app.

read more at https://prometheus.io/

Closes #98

docs/api/index.md

@@ -7,4 +7,8 @@ Version: 1.0
 * [Feature Toggles API](feature-toggles-api.md)
 * [Strategies API](strategies-api.md)
 * [Events API](events-api.md)
-* [Metrics API](metrics-api.md)
+* [Metrics API](metrics-api.md)
+
+
+Others: 
+* [Internal Backstage API](internal-backstage-api.ms)

docs/api/internal-backstage-api.md

@@ -0,0 +1,8 @@
+# Internal Backstage API
+
+`GET http://unleash.host.com/internal-backstage/prometheus`
+
+Unleash uses prometheus internally to collect metrics. These are
+available on the given url if the `serverMetrics` option is enabled (default=true).
+
+[Read more about Prometheus](https://prometheus.io/) 

lib/events.js

@@ -0,0 +1,6 @@
+module.exports =  {
+    TOGGLES_FETCH: 'toggles:fetch',
+    TOGGLES_CREATE: 'toggles:create',
+    CLIENT_REGISTER: 'client:register',
+    CLIENT_METRICS: 'toggles:metrics',
+}

lib/metrics.js

@@ -0,0 +1,24 @@
+const events = require('./events');
+
+exports.startMonitoring = (enable, eventBus) => {
+    if (!enable) {
+        return;
+    }
+
+    const client = require('prom-client');
+    const toggleFetch = new client.Counter('toggles_fetch_counter', 'Number of fetch toggles request');
+    const clientRegister = new client.Counter('client_register_counter', 'Number client register requests');
+    const clientMetrics = new client.Counter('client_metrics_counter', 'Number client metrics requests');
+
+    eventBus.on(events.TOGGLES_FETCH, () => {
+        toggleFetch.inc();
+    });
+
+    eventBus.on(events.CLIENT_REGISTER, () => {
+        clientRegister.inc();
+    });
+
+    eventBus.on(events.CLIENT_METRICS, () => {
+        clientMetrics.inc();
+    });
+};

lib/options.js

@@ -0,0 +1,18 @@
+'use strict';
+
+const DEFAULT_OPTIONS = {
+    databaseUri: process.env.DATABASE_URL || 'postgres://unleash_user:passord@localhost:5432/unleash',
+    port: process.env.HTTP_PORT || process.env.PORT || 4242,
+    baseUriPath: process.env.BASE_URI_PATH || '',
+    serverMetrics: true,
+};
+
+module.exports = {
+    createOptions: (opts) => {
+        const options =  Object.assign({}, DEFAULT_OPTIONS, opts);
+         if (!options.databaseUri) {
+            throw new Error('You must either pass databaseUri option or set environemnt variable DATABASE_URL');
+        }
+        return options;
+    }
+}

lib/routes/backstage.js

@@ -0,0 +1,12 @@
+'use strict';
+
+const prometheusRegister = require('prom-client/lib/register');
+
+module.exports = function (app, config) {
+    if(config.serverMetrics) {
+        app.get('/internal-backstage/prometheus', (req, res) => {
+            res.writeHead(200, { 'Content-Type': 'text/plain' });
+            res.end(prometheusRegister.metrics());
+        });
+    }
+};

lib/routes/feature.js

@@ -8,6 +8,8 @@ const ValidationError = require('../error/validation-error.js');
 const validateRequest = require('../error/validate-request');
 const extractUser = require('../extract-user');
 
+const { TOGGLES_FETCH } = require('../events');
+
 const legacyFeatureMapper = require('../data-helper/legacy-feature-mapper');
 const version = 1;
 
@@ -37,8 +39,11 @@ const handleErrors = (req, res, error) => {
 
 module.exports = function (app, config) {
     const { featureToggleStore, eventStore } = config.stores;
+    const { eventBus } = config;
 
     app.get('/features', (req, res) => {
+        eventBus.emit(TOGGLES_FETCH);
+
         featureToggleStore.getFeatures()
             .then((features) => features.map(legacyFeatureMapper.addOldFields))
             .then(features => res.json({ version, features }));

lib/routes/index.js

@@ -13,4 +13,5 @@ exports.createAPI = function (router, config) {
 exports.createLegacy = function (router, config) {
     require('./feature')(router, config);
     require('./health-check')(router, config);
+    require('./backstage')(router, config);
 };

lib/routes/metrics.js

@@ -4,7 +4,7 @@ const logger = require('../logger');
 const ClientMetrics = require('../client-metrics');
 const joi = require('joi');
 const { clientMetricsSchema, clientRegisterSchema } = require('./metrics-schema');
-
+const { CLIENT_REGISTER, CLIENT_METRICS } = require('../events');
 /*
 * TODO: 
 *  - always catch errors and always return a response to client!
@@ -18,6 +18,8 @@ module.exports = function (app, config) {
         clientStrategyStore,
         clientInstanceStore,
     } = config.stores;
+
+    const { eventBus } = config;
     
     const metrics = new ClientMetrics(clientMetricsStore);
     
@@ -39,6 +41,8 @@ module.exports = function (app, config) {
                 return res.status(400).json(err);
             }
 
+            eventBus.emit(CLIENT_METRICS);
+
             clientMetricsStore
                 .insert(cleaned)
                 .then(() => clientInstanceStore.insert({
@@ -61,6 +65,8 @@ module.exports = function (app, config) {
                 return res.status(400).json(err);
             }
 
+            eventBus.emit(CLIENT_REGISTER);
+
             clientStrategyStore
                 .insert(cleaned.appName, cleaned.strategies)
                 .then(() => clientInstanceStore.insert({

lib/server-impl.js

@@ -1,40 +1,42 @@
 'use strict';
 
+const { EventEmitter } = require('events');
+
 const logger = require('./logger');
 const migrator = require('../migrator');
-const { createStores } = require('./db');
 const getApp = require('./app');
+const events = require('./events');
 
-const DEFAULT_OPTIONS = {
-    databaseUri: process.env.DATABASE_URL || 'postgres://unleash_user:passord@localhost:5432/unleash',
-    port: process.env.HTTP_PORT || process.env.PORT || 4242,
-    baseUriPath: process.env.BASE_URI_PATH || '',
-};
+const { startMonitoring } = require('./metrics');
+const { createStores } = require('./db');
+const { createOptions } = require('./options');
 
 function createApp (options) {
     // Database dependecies (statefull)
     const stores = createStores(options);
+    const eventBus = new EventEmitter();
 
     const config = {
+        prometheusPath: options.prometheusPath,
         baseUriPath: options.baseUriPath,
         port: options.port,
         publicFolder: options.publicFolder,
         stores,
+        eventBus,
     };
 
     const app = getApp(config);
     const server = app.listen(app.get('port'), () => {
         logger.info(`Unleash started on ${app.get('port')}`);
     });
-    return { app, server };
+
+    startMonitoring(options.serverMetrics, eventBus);
+
+    return { app, server, eventBus };
 }
 
 function start (opts) {
-    const options = Object.assign({}, DEFAULT_OPTIONS, opts);
-
-    if (!options.databaseUri) {
-        throw new Error('You must either pass databaseUri option or set environemnt variable DATABASE_URL');
-    }
+    const options = createOptions(opts);
 
     return migrator({ databaseUri: options.databaseUri })
         .catch(err => logger.error('failed to migrate db', err))

package.json

@@ -71,6 +71,7 @@
     "moment": "^2.15.2",
     "parse-database-url": "^0.3.0",
     "pg": "^6.1.0",
+    "prom-client": "^6.1.2",
     "serve-favicon": "^2.3.0",
     "unleash-frontend": "github:unleash/unleash-frontend",
     "yallist": "^2.0.0"

test/e2e/helpers/test-helper.js

@@ -15,6 +15,9 @@ require('db-migrate-shared').log.silence(true);
 // because of migrator bug
 delete process.env.DATABASE_URL;
 
+const { EventEmitter } = require('events');
+const eventBus = new EventEmitter();
+
 function createApp (databaseSchema = 'test') {
     const options = {
         databaseUri: require('./database-config').getDatabaseUri(),
@@ -29,7 +32,7 @@ function createApp (databaseSchema = 'test') {
         .then(() => {
             db.destroy();
             const stores = createStores(options);
-            const app = getApp({ stores });
+            const app = getApp({ stores, eventBus });
             return {
                 stores,
                 request: supertest(app),

test/unit/routes/backstage.test.js

@@ -0,0 +1,31 @@
+'use strict';
+
+const test = require('ava');
+const store = require('./fixtures/store');
+const supertest = require('supertest');
+const logger = require('../../../lib/logger');
+const getApp = require('../../../lib/app');
+
+const { EventEmitter } = require('events');
+const eventBus = new EventEmitter();
+
+test.beforeEach(() =>  {
+    logger.setLevel('FATAL');
+});
+
+test('should use enable prometheus', t => {
+    const stores = store.createStores();
+    const app = getApp({
+        baseUriPath: '',
+        serverMetrics: true,
+        stores,
+        eventBus,
+    });
+
+    const request = supertest(app);
+
+    return request
+        .get('/internal-backstage/prometheus')
+        .expect('Content-Type', /text/)
+        .expect(200)
+});

test/unit/routes/feature.test.js

@@ -6,6 +6,9 @@ const supertest = require('supertest');
 const logger = require('../../../lib/logger');
 const getApp = require('../../../lib/app');
 
+const { EventEmitter } = require('events');
+const eventBus = new EventEmitter();
+
 test.beforeEach(() =>  {
     logger.setLevel('FATAL');
 });
@@ -16,6 +19,7 @@ function getSetup () {
     const app = getApp({
         baseUriPath: base,
         stores,
+        eventBus,
     });
 
     return {

test/unit/routes/health-check.test.js

@@ -6,6 +6,9 @@ const supertest = require('supertest');
 const logger = require('../../../lib/logger');
 const getApp = require('../../../lib/app');
 
+const { EventEmitter } = require('events');
+const eventBus = new EventEmitter();
+
 test.beforeEach(() =>  {
     logger.setLevel('FATAL');
 });
@@ -17,6 +20,7 @@ function getSetup () {
     const app = getApp({
         baseUriPath: '',
         stores,
+        eventBus,
     });
 
     return {

test/unit/routes/metrics.test.js

@@ -6,6 +6,9 @@ const supertest = require('supertest');
 const logger = require('../../../lib/logger');
 const getApp = require('../../../lib/app');
 
+const { EventEmitter } = require('events');
+const eventBus = new EventEmitter();
+
 test.beforeEach(() =>  {
     logger.setLevel('FATAL');
 });
@@ -15,6 +18,7 @@ function getSetup () {
     const app = getApp({
         baseUriPath: '',
         stores,
+        eventBus,
     });
 
     return {

test/unit/routes/strategies.test.js

@@ -6,6 +6,9 @@ const supertest = require('supertest');
 const logger = require('../../../lib/logger');
 const getApp = require('../../../lib/app');
 
+const { EventEmitter } = require('events');
+const eventBus = new EventEmitter();
+
 test.beforeEach(() =>  {
     logger.setLevel('FATAL');
 });
@@ -15,6 +18,7 @@ test('should add version numbers for /stategies', t => {
     const app = getApp({
         baseUriPath: '',
         stores,
+        eventBus,
     });
 
     const request = supertest(app);