# Install and use metrics with Prometheus and Grafana

## Install metrics agents

Install Prometheus, Prometheus Pushgateway and Grafana. Put them behind NGINX reverse proxy, get a TLS certificate, and run the service on startup with systemd.

Do a replace all of prometheus-pushgateway.example.com and grafana.example.com with your own domains.

```sh
chmod u+x ./install_metrics_agents.sh
sudo ./install_metrics_agents.sh
```

## Configure Grafana dashboard

Go to https://grafana.example.com, log in with `admin:admin` and set your new secure password.

In `Connections` > `Data sources`, Select `Prometheus`. In the host field, enter `http://localhost:9090`, and save. It should say that the connection was succesful.

## Push some metrics in Node.js

Install required dependencies

```sh
pnpm i prom-client
```

In the entrypoint of your Node.js project, simply import [metrics.mjs](#file-metrics-mjs).
Pass the host where your Prometheus Pushgateway is deployed with `PROMETHEUS_GATEWAY_ENDPOINT=https://prometheus-pushgateway.example.com`.

To increment the counter metric named `my_metric`, simply call:

```js
MetricsUtils.my_metric.inc()
```

Check the [`prom-client`](https://github.com/siimon/prom-client/) repository for further documentation.