Simplify metrics: We only need timings as it includes counts for free

lib/app.js

@@ -12,7 +12,7 @@ const routes = require('./routes');
 const path = require('path');
 const errorHandler = require('errorhandler');
 
-const {REQUEST_TIME, REQUEST_STATUS} = require('./events');
+const {REQUEST_TIME} = require('./events');
 
 module.exports = function (config) {
     const app = express();
@@ -30,8 +30,8 @@ module.exports = function (config) {
     }
 
     app.use(responseTime((req, res, time) => {
-        config.eventBus.emit(REQUEST_TIME, req.path, req.method, time);
+        const timingInfo = { path: req.path, method: req.method, statusCode: res.statusCode, time };
-        config.eventBus.emit(REQUEST_STATUS, req.path, req.method, res.statusCode);
+        config.eventBus.emit(REQUEST_TIME, timingInfo);
     }));
 
     app.use(validator([]));

lib/events.js

@@ -1,8 +1,3 @@
 module.exports =  {
-    TOGGLES_FETCH: 'toggles:fetch',
-    TOGGLES_CREATE: 'toggles:create',
-    CLIENT_REGISTER: 'client:register',
-    CLIENT_METRICS: 'toggles:metrics',
     REQUEST_TIME: 'request_time',
-    REQUEST_STATUS: 'request_status'
 }

lib/metrics.js

@@ -6,33 +6,12 @@ exports.startMonitoring = (enable, eventBus) => {
     }
 
     const client = require('prom-client');
-    const toggleFetch = new client.Counter('toggles_fetch_counter', 'Number of fetch toggles request');
     
-    const requestDuration = new client.Summary('http_request_duration_milliseconds', 'App response time', ['uri', 'method'], {
+    const requestDuration = new client.Summary('http_request_duration_milliseconds', 'App response time', ['path', 'method', 'status'], {
         percentiles: [0.1, 0.5, 0.9, 0.99],
     });
-    const requestCount = new client.Counter('http_requests_total', 'HTTP request duration', ['uri', 'method', 'status']);
 
-    const clientRegister = new client.Counter('client_register_counter', 'Number client register requests');
+    eventBus.on(events.REQUEST_TIME, ({path, method, time, statusCode}) => {
-    const clientMetrics = new client.Counter('client_metrics_counter', 'Number client metrics requests');
+        requestDuration.labels(path, method, statusCode).observe(time);
-
-    eventBus.on(events.TOGGLES_FETCH, () => {
-        toggleFetch.inc();
-    });
-
-    eventBus.on(events.CLIENT_REGISTER, () => {
-        clientRegister.inc();
-    });
-
-    eventBus.on(events.CLIENT_METRICS, () => {
-        clientMetrics.inc();
-    });
-
-    eventBus.on(events.REQUEST_TIME, (uri, method, time) => {
-        requestDuration.labels(uri, method).observe(time);
-    });
-
-    eventBus.on(events.REQUEST_STATUS, (uri, method, status) => {
-        requestCount.labels(uri, method, status).inc();
     });
 };

lib/metrics.test.js

@@ -0,0 +1,16 @@
+
+const test = require('ava');
+const { EventEmitter } = require('events');
+const eventBus = new EventEmitter();
+const { REQUEST_TIME } = require('./events');
+const { startMonitoring } = require('./metrics');
+const prometheusRegister = require('prom-client/lib/register');
+
+test('should collect metrics for requests', t => {
+    startMonitoring(true, eventBus);
+    eventBus.emit(REQUEST_TIME, { path: 'somePath', method: 'GET', statusCode: 200, time: 1337 });
+    
+    const metrics = prometheusRegister.metrics();
+    t.regex(metrics, /http_request_duration_milliseconds{quantile="0.99",status="200",method="GET",path="somePath"} 1337/)
+    
+});

lib/routes/feature.js

@@ -8,8 +8,6 @@ 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;
 
@@ -39,11 +37,8 @@ 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/metrics.js

@@ -4,7 +4,6 @@ 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');
 const { catchLogAndSendErrorResponse } = require('./route-utils');
 
 module.exports = function (app, config) {
@@ -14,8 +13,6 @@ module.exports = function (app, config) {
         clientInstanceStore,
     } = config.stores;
 
-    const { eventBus } = config;
-    
     const metrics = new ClientMetrics(clientMetricsStore);
     
     app.get('/client/seen-toggles', (req, res) => {
@@ -36,8 +33,6 @@ module.exports = function (app, config) {
                 return res.status(400).json(err);
             }
 
-            eventBus.emit(CLIENT_METRICS);
-
             clientMetricsStore
                 .insert(cleaned)
                 .then(() => clientInstanceStore.insert({
@@ -60,8 +55,6 @@ module.exports = function (app, config) {
                 return res.status(400).json(err);
             }
 
-            eventBus.emit(CLIENT_REGISTER);
-
             clientStrategyStore
                 .insert(cleaned.appName, cleaned.strategies)
                 .then(() => clientInstanceStore.insert({