From 0e1b0e912ec8ba8d24e09ffb8cfd6ad1930461ef Mon Sep 17 00:00:00 2001
From: Tiago0507 <svalenciagarcia707@gmail.com>
Date: Sun, 23 Aug 2026 21:26:01 -0500
Subject: [PATCH] feat: add request duration histogram for golden-signal
 latency

---
 server.js | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/server.js b/server.js
index e94c5f0..8ca505f 100644
--- a/server.js
+++ b/server.js
@@ -61,6 +61,12 @@ function createApp (options = {}) {
     labelNames: ['method', 'status'],
     registers: [register]
   });
+  const requestDuration = new prometheus.Histogram({
+    name: 'todo_api_request_duration_seconds',
+    help: 'Duration of requests handled by the Todo API',
+    labelNames: ['method'],
+    registers: [register]
+  });
   prometheus.collectDefaultMetrics({ register, prefix: 'todos_api_' });
 
   app.get('/metrics', async (req, res) => {
@@ -69,7 +75,11 @@ function createApp (options = {}) {
   });
 
   app.use((req, res, next) => {
-    res.on('finish', () => requestCount.labels(req.method, String(res.statusCode)).inc());
+    const stopTimer = requestDuration.startTimer({ method: req.method });
+    res.on('finish', () => {
+      requestCount.labels(req.method, String(res.statusCode)).inc();
+      stopTimer();
+    });
     next();
   });
   app.use(expressjwt({