fix: add appName to http response time metrics (#2117)

src/lib/__snapshots__/create-config.test.ts.snap

@@ -73,6 +73,7 @@ exports[`should create default config 1`] = `
       "embedProxyFrontend": false,
       "personalAccessTokens": false,
       "publicSignup": false,
+      "responseTimeWithAppName": false,
     },
   },
   "flagResolver": FlagResolver {
@@ -84,6 +85,7 @@ exports[`should create default config 1`] = `
       "embedProxyFrontend": false,
       "personalAccessTokens": false,
       "publicSignup": false,
+      "responseTimeWithAppName": false,
     },
     "externalResolver": {
       "isEnabled": [Function],

src/lib/app.ts

@@ -42,7 +42,7 @@ export default async function getApp(
     app.set('port', config.server.port);
     app.locals.baseUriPath = baseUriPath;
     if (config.server.serverMetrics && config.eventBus) {
-        app.use(responseTimeMetrics(config.eventBus));
+        app.use(responseTimeMetrics(config.eventBus, config.flagResolver));
     }
 
     app.use(requestLogger(config));

src/lib/metrics.test.ts

@@ -53,7 +53,7 @@ test('should collect metrics for requests', async () => {
 
     const metrics = await prometheusRegister.metrics();
     expect(metrics).toMatch(
-        /http_request_duration_milliseconds{quantile="0\.99",path="somePath",method="GET",status="200"}.*1337/,
+        /http_request_duration_milliseconds{quantile="0\.99",path="somePath",method="GET",status="200",appName="undefined"}.*1337/,
     );
 });
 

src/lib/metrics.ts

@@ -57,7 +57,7 @@ export default class MetricsMonitor {
         const requestDuration = new client.Summary({
             name: 'http_request_duration_milliseconds',
             help: 'App response time',
-            labelNames: ['path', 'method', 'status'],
+            labelNames: ['path', 'method', 'status', 'appName'],
             percentiles: [0.1, 0.5, 0.9, 0.95, 0.99],
             maxAgeSeconds: 600,
             ageBuckets: 5,
@@ -143,8 +143,10 @@ export default class MetricsMonitor {
 
         eventBus.on(
             events.REQUEST_TIME,
-            ({ path, method, time, statusCode }) => {
-                requestDuration.labels(path, method, statusCode).observe(time);
+            ({ path, method, time, statusCode, appName }) => {
+                requestDuration
+                    .labels(path, method, statusCode, appName)
+                    .observe(time);
             },
         );
 

src/lib/middleware/response-time-metrics.ts

@@ -1,21 +1,31 @@
 import * as responseTime from 'response-time';
 import EventEmitter from 'events';
 import { REQUEST_TIME } from '../metric-events';
+import { IFlagResolver } from '../types/experimental';
 
 // eslint-disable-next-line @typescript-eslint/naming-convention
 const _responseTime = responseTime.default;
 
-export function responseTimeMetrics(eventBus: EventEmitter): any {
+export function responseTimeMetrics(
+    eventBus: EventEmitter,
+    flagResolver: IFlagResolver,
+): any {
     return _responseTime((req, res, time) => {
         const { statusCode } = res;
 
         const pathname = req.route ? req.baseUrl + req.route.path : '(hidden)';
 
+        let appName;
+        if (flagResolver.isEnabled('responseTimeWithAppName')) {
+            appName = req.headers['unleash-appname'];
+        }
+
         const timingInfo = {
             path: pathname,
             method: req.method,
             statusCode,
             time,
+            appName,
         };
         eventBus.emit(REQUEST_TIME, timingInfo);
     });

src/lib/types/experimental.ts

@@ -26,6 +26,10 @@ export const defaultExperimentalOptions = {
             process.env.UNLEASH_EXPERIMENTAL_PUBLIC_SIGNUP,
             false,
         ),
+        responseTimeWithAppName: parseEnvVarBoolean(
+            process.env.UNLEASH_EXPERIMENTAL_RESPONSE_TIME_WITH_APP_NAME,
+            false,
+        ),
     },
     externalResolver: { isEnabled: (): boolean => false },
 };

src/server-dev.ts

@@ -37,6 +37,7 @@ process.nextTick(async () => {
                         embedProxyFrontend: true,
                         batchMetrics: true,
                         anonymiseEventLog: false,
+                        responseTimeWithAppName: true,
                     },
                 },
                 authentication: {