How are these metrics integrated and displayed in Grafana?

To integrate metrics into Grafana, it is usually connected with metrics collection systems such as Prometheus.

1. Metrics collection: In a Go application, metrics (counters, histograms, etc.) are created and updated using libraries (for example, prometheus/client_golang).

2. Metrics exposition: The application runs an HTTP server that exposes the current metric values at a specific endpoint (e.g., /metrics) in a format understandable by Prometheus.

3. Prometheus collection: Prometheus periodically polls this endpoint and stores the data in its database.

4. Visualization in Grafana: Grafana connects to Prometheus as a data source and visualizes metrics using dashboards and graphs.

Thus, Grafana itself does not collect metrics but displays them from monitoring systems that integrate with the application.

Example of exposing metrics in Go:

import (
    "net/http"
    "github.com/prometheus/client_golang/prometheus"
    "github.com/prometheus/client_golang/prometheus/promhttp"
)

var opsProcessed = prometheus.NewCounter(prometheus.CounterOpts{
    Name: "myapp_processed_ops_total",
    Help: "The total number of processed events",
})

func init() {
    prometheus.MustRegister(opsProcessed)
}

func main() {
    http.Handle("/metrics", promhttp.Handler())
    http.ListenAndServe(":2112", nil)
}

After that, Prometheus is configured to collect metrics from http://app_host:2112/metrics, and Grafana is set to display data from Prometheus.