Have you had experience using libraries for integration with Prometheus?

Yes, there is an official client library for integrating with Prometheus in Go — the prometheus/client_golang package. It allows you to create and register metrics (counters, histograms, summaries, etc.), which can then be exported for Prometheus collection.

Example usage:

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

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

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

func handler(w http.ResponseWriter, r *http.Request) {
    opsProcessed.Inc()
    w.Write([]byte("Hello, Prometheus!"))
}

func main() {
    http.Handle("/metrics", promhttp.Handler())
    http.HandleFunc("/", handler)
    http.ListenAndServe(":8080", nil)
}

This approach makes it easy to integrate metrics into your application and collect them with Prometheus.