From d6365787617f2da56dacf1bc830c61879a43307d Mon Sep 17 00:00:00 2001
From: soufiane <soufiane.baali99@gmail.com>
Date: Tue, 25 Nov 2025 16:24:33 +0100
Subject: [PATCH] fix: use singleton pattern and force nodejs runtime for
 metrics route
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- Add runtime = 'nodejs' to ensure Node.js environment
- Add dynamic = 'force-dynamic' to prevent static optimization
- Use singleton pattern to avoid duplicate metric registration
- Add error logging for debugging

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>
---
 app/api/metrics/route.ts | 62 ++++++++++++++++++++++++++++------------
 1 file changed, 44 insertions(+), 18 deletions(-)

diff --git a/app/api/metrics/route.ts b/app/api/metrics/route.ts
index ed30948..a150f48 100644
--- a/app/api/metrics/route.ts
+++ b/app/api/metrics/route.ts
@@ -1,30 +1,55 @@
 import { NextResponse } from 'next/server';
 import client from 'prom-client';
 
-// Create a Registry to register the metrics
-const register = new client.Registry();
+// Force Node.js runtime for this route
+export const runtime = 'nodejs';
+export const dynamic = 'force-dynamic';
 
-// Add default metrics (CPU, memory, etc.)
-client.collectDefaultMetrics({ register });
+// Singleton pattern to avoid duplicate metric registration
+const globalForProm = globalThis as unknown as {
+  promRegistry: client.Registry | undefined;
+  metricsInitialized: boolean | undefined;
+};
 
-// Custom metrics
-const httpRequestsTotal = new client.Counter({
-  name: 'http_requests_total',
-  help: 'Total number of HTTP requests',
-  labelNames: ['method', 'path', 'status'],
-  registers: [register],
-});
+function getRegistry(): client.Registry {
+  if (!globalForProm.promRegistry) {
+    globalForProm.promRegistry = new client.Registry();
+  }
+  return globalForProm.promRegistry;
+}
 
-const httpRequestDuration = new client.Histogram({
-  name: 'http_request_duration_seconds',
-  help: 'Duration of HTTP requests in seconds',
-  labelNames: ['method', 'path'],
-  buckets: [0.1, 0.3, 0.5, 0.7, 1, 3, 5, 7, 10],
-  registers: [register],
-});
+function initializeMetrics(register: client.Registry) {
+  if (globalForProm.metricsInitialized) {
+    return;
+  }
+
+  // Add default metrics (CPU, memory, etc.)
+  client.collectDefaultMetrics({ register });
+
+  // Custom metrics
+  new client.Counter({
+    name: 'http_requests_total',
+    help: 'Total number of HTTP requests',
+    labelNames: ['method', 'path', 'status'],
+    registers: [register],
+  });
+
+  new client.Histogram({
+    name: 'http_request_duration_seconds',
+    help: 'Duration of HTTP requests in seconds',
+    labelNames: ['method', 'path'],
+    buckets: [0.1, 0.3, 0.5, 0.7, 1, 3, 5, 7, 10],
+    registers: [register],
+  });
+
+  globalForProm.metricsInitialized = true;
+}
 
 export async function GET() {
   try {
+    const register = getRegistry();
+    initializeMetrics(register);
+
     const metrics = await register.metrics();
     return new NextResponse(metrics, {
       status: 200,
@@ -33,6 +58,7 @@ export async function GET() {
       },
     });
   } catch (error) {
+    console.error('Metrics error:', error);
     return NextResponse.json({ error: 'Failed to get metrics' }, { status: 500 });
   }
 }