Server Metrics: add response time and status codes

lib/app.js

@@ -5,12 +5,15 @@ const favicon = require('serve-favicon');
 const bodyParser = require('body-parser');
 const cookieParser = require('cookie-parser');
 const validator = require('express-validator');
+const responseTime = require('response-time');
 const log4js = require('log4js');
 const logger = require('./logger');
 const routes = require('./routes');
 const path = require('path');
 const errorHandler = require('errorhandler');
 
+const {REQUEST_TIME, REQUEST_STATUS} = require('./events');
+
 module.exports = function (config) {
     const app = express();
 
@@ -26,7 +29,13 @@ module.exports = function (config) {
         app.use(favicon(path.join(publicFolder, 'favicon.ico')));
     }
 
+    app.use(responseTime((req, res, time) => {
+        config.eventBus.emit(REQUEST_TIME, req.path, req.method, time);
+        config.eventBus.emit(REQUEST_STATUS, req.path, req.method, res.statusCode);
+    }));
+
     app.use(validator([]));
+
     if (publicFolder) {
         app.use(baseUriPath, express.static(publicFolder));
     }

lib/events.js

@@ -3,4 +3,6 @@ module.exports =  {
     TOGGLES_CREATE: 'toggles:create',
     CLIENT_REGISTER: 'client:register',
     CLIENT_METRICS: 'toggles:metrics',
+    REQUEST_TIME: 'request_time',
+    REQUEST_STATUS: 'request_status'
 }

lib/metrics.js

@@ -7,6 +7,12 @@ 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'], {
+        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');
     const clientMetrics = new client.Counter('client_metrics_counter', 'Number client metrics requests');
 
@@ -21,4 +27,12 @@ exports.startMonitoring = (enable, eventBus) => {
     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/routes/backstage.js

@@ -3,6 +3,7 @@
 const prometheusRegister = require('prom-client/lib/register');
 
 module.exports = function (app, config) {
+    console.log({config});
     if(config.serverMetrics) {
         app.get('/internal-backstage/prometheus', (req, res) => {
             res.writeHead(200, { 'Content-Type': 'text/plain' });

lib/server-impl.js

@@ -17,8 +17,8 @@ function createApp (options) {
     const eventBus = new EventEmitter();
 
     const config = {
-        prometheusPath: options.prometheusPath,
         baseUriPath: options.baseUriPath,
+        serverMetrics: options.serverMetrics,
         port: options.port,
         publicFolder: options.publicFolder,
         stores,

package.json

@@ -72,6 +72,7 @@
     "parse-database-url": "^0.3.0",
     "pg": "^6.1.0",
     "prom-client": "^6.1.2",
+    "response-time": "^2.3.2",
     "serve-favicon": "^2.3.0",
     "unleash-frontend": "github:unleash/unleash-frontend",
     "yallist": "^2.0.0"