How can metrics be transmitted from an application to Grafana for visualization and monitoring?

To transmit metrics from a Go application to Grafana, the Prometheus monitoring system is usually used, which integrates well with Grafana.

Main steps:

1. In the Go application, connect the Prometheus client library (prometheus/client_golang).
2. Define and register metrics (counters, histograms, gauges).
3. Run an HTTP server with an endpoint /metrics that provides current metric values in a format understandable by Prometheus.
4. Configure Prometheus to collect metrics from this endpoint.
5. Connect Grafana to Prometheus as a data source and visualize the metrics.

Example code 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())
    go func() {
        for {
            opsProcessed.Inc() // increment the counter
            time.Sleep(time.Second)
        }
    }()
    http.ListenAndServe(":2112", nil)
}

Thus, metrics become available for collection by Prometheus and subsequent visualization in Grafana.