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Monitoring Node.js Applications with Prometheus

Professional

You can instrument your Node.js application with prom-client and let the Glouton agent scrape its /metrics endpoint.

Install the client library

npm install prom-client express

Minimal example

The snippet below defines a counter and exposes it on http://localhost:8080/metrics:

const express = require("express");
const client = require("prom-client");

const requestsTotal = new client.Counter({
  name: "myapp_requests_total",
  help: "Total number of processed requests.",
});

const app = express();

app.get("/", (req, res) => {
  requestsTotal.inc();
  res.send("Hello");
});

app.get("/metrics", async (req, res) => {
  res.set("Content-Type", client.register.contentType);
  res.end(await client.register.metrics());
});

app.listen(8080);

Scrape with Glouton

Configure Glouton to scrape your application by adding the following to /etc/glouton/conf.d/50-prometheus-metrics.conf:

metric:
  prometheus:
    targets:
      - url: "http://localhost:8080/metrics"
        name: "my_nodejs_application"
        allow_metrics:
          - "myapp_requests_total"

Restart the agent to apply the configuration. See Prometheus Monitoring for the full list of options, including Docker label auto-discovery and Kubernetes annotations.

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