Grafana Prometheus Nodejs Integration Steps using prom-client

gistfile1.txt

# Pre-requisite

Should have node >=12

# Install

npm i prom-client


# Setup
1. Create a Grafana.js file

//Grafana.js
```
import { collectDefaultMetrics, register } from 'prom-client' 
async function initializeGrafana (_req, res) {
  try {
    res.set('Content-Type', register.contentType)
    return res.end(await register.metrics())
  } catch (err) {
      return res.status(500).end(err)
  }
}
export { collectDefaultMetrics, initializeGrafana }
```


2. Import Grafana in you server start file (usually server.js or app.js), 
This is the file where your express app is first initialized

```
import { collectDefaultMetrics, initializeGrafana } from './Grafana'

// keep this on the top before initializing the express app
collectDefaultMetrics()

// place this right after `const app = new Express()`
app.get('/metrics', initializeGrafana)
```

3. Check response for `curl localhost:4001/metrics` from shell
You should see something like this if everything was done correctly

```
# HELP nodejs_gc_duration_seconds Garbage collection duration by kind, one of major, minor, incremental or weakcb.
# TYPE nodejs_gc_duration_seconds histogram
nodejs_gc_duration_seconds_bucket{le="0.001",kind="incremental"} 2
nodejs_gc_duration_seconds_bucket{le="0.01",kind="incremental"} 4
nodejs_gc_duration_seconds_bucket{le="0.1",kind="incremental"} 4
nodejs_gc_duration_seconds_bucket{le="1",kind="incremental"} 4
nodejs_gc_duration_seconds_bucket{le="2",kind="incremental"} 4
```


# Reference
https://grafana.com/oss/prometheus/exporters/nodejs-exporter/?tab=installation#introduction