# Prometheus Monitoring with Node.js This project integrates **Prometheus** with a **Node.js application**, allowing you to monitor metrics both locally and on **Render**. --- ## Project Structure ``` C:\Prometheus\prometheus-3.6.0.windows-amd64\ │ prometheus.exe │ prometheus.yml │ ... NodeApp\ │ server.js │ package.json │ ... ``` --- ## Prometheus Configuration (`prometheus.yml`) ```yaml global: scrape_interval: 15s evaluation_interval: 15s scrape_configs: # Scrape Prometheus itself - job_name: "prometheus" static_configs: - targets: ["localhost:9090"] labels: app: "prometheus" # Scrape Node.js app locally - job_name: "nodejs-app" static_configs: - targets: ["localhost:3000"] labels: app: "nodejs-app" # Scrape Node.js app on Render - job_name: "nodejs-app-render" scheme: https static_configs: - targets: ["my-app.onrender.com"] labels: app: "nodejs-app" tls_config: insecure_skip_verify: true ``` **Important:** - Do **not** add `https://` in `targets`. Use just the domain/host. - Use `scheme: https` for HTTPS connections. --- ## Running Prometheus 1. Open **PowerShell** and go to the Prometheus folder: ```powershell cd C:\Prometheus\prometheus-3.6.0.windows-amd64 ``` 2. Start Prometheus: ```powershell .\prometheus.exe --config.file=prometheus.yml --web.enable-lifecycle ``` 3. Open the UI in your browser: [http://localhost:9090](http://localhost:9090) --- ## Reload Prometheus Config If you change `prometheus.yml`, reload Prometheus without restarting: ```powershell curl.exe -X POST http://localhost:9090/-/reload ``` --- ## Verify Targets To check active targets: ```powershell curl.exe http://localhost:9090/api/v1/targets ``` Or visit in browser: [http://localhost:9090/targets](http://localhost:9090/targets) You should see jobs for: - `prometheus` - `nodejs-app` - `nodejs-app-render` --- ## Node.js App Setup Example **`server.js`** with metrics using `prom-client`: ```js import express from "express"; import client from "prom-client"; const app = express(); const port = 3000; // Create a registry and collect default system metrics const register = new client.Registry(); client.collectDefaultMetrics({ register }); // Example counter const httpRequests = new client.Counter({ name: "http_requests_total", help: "Total number of HTTP requests", labelNames: ["method", "route", "status"], }); register.registerMetric(httpRequests); // Middleware to track requests app.use((req, res, next) => { res.on("finish", () => { httpRequests.inc({ method: req.method, route: req.route ? req.route.path : req.path, status: res.statusCode, }); }); next(); }); // Example routes app.get("/", (req, res) => res.send("Hello from Node.js!")); app.get("/api/test", (req, res) => res.json({ msg: "Testing API" })); // Expose metrics app.get("/metrics", async (req, res) => { res.set("Content-Type", register.contentType); res.end(await register.metrics()); }); app.listen(port, () => { console.log(` App running on port ${port}`); }); ``` --- ## Test Endpoints - Local Prometheus: [http://localhost:9090](http://localhost:9090) - Local metrics: [http://localhost:3000/metrics](http://localhost:3000/metrics) - Render metrics: [https://my-app.onrender.com/metrics](https://my-app.onrender.com/metrics) --- ## Troubleshooting - If only Prometheus is scraping, check your Node.js app is running (`npm run dev`). - Ensure `prometheus.yml` is in the **same folder** as `prometheus.exe`. - Only keep **one Prometheus installation folder** to avoid conflicts. - Use `--web.enable-lifecycle` so config reload works. --- ## Example PromQL Queries Inside Prometheus UI, try: - Total requests: ``` http_requests_total ``` - Requests per second: ``` rate(http_requests_total[1m]) ``` - Node.js CPU/memory metrics: ``` process_cpu_seconds_total process_resident_memory_bytes ``` --- With this setup, Prometheus scrapes both your **local app** and your **Render app** successfully. # DF-2.0-AIMA-Prometheus