feat: nodejs test app

Author: pythoninthegrass

app/app.js

@@ -0,0 +1,17 @@
+import express from 'express';
+import { collectDefaultMetrics, register } from 'prom-client';
+
+collectDefaultMetrics();
+
+const app = express();
+
+app.get('/metrics', async (_req, res) => {
+  try {
+    res.set('Content-Type', register.contentType);
+    res.end(await register.metrics());
+  } catch (err) {
+    res.status(500).end(err);
+  }
+});
+
+app.listen(4001, '0.0.0.0');