How was data collected from metrics?

Data collection from metrics in Go is usually carried out using specialized libraries, such as the Prometheus client_golang. The process includes:

1. Defining metrics (counters, histograms, gauges, etc.) in the code.
2. Updating metrics at the necessary points in the program.
3. Exposing metrics via an HTTP endpoint, from which the monitoring system collects them.

Example of using Prometheus in Go:

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 main() {
    http.Handle("/metrics", promhttp.Handler())
    go func() {
        for {
            opsProcessed.Inc() // increment the counter
            time.Sleep(time.Second)
        }
    }()
    http.ListenAndServe(":2112", nil)
}

Thus, collecting data from metrics is a process of defining, updating, and exposing metrics for subsequent analysis.