metrics

package metrics

package metrics provides a set of uniform interfaces for service instrumentation. It has counters, gauges, and histograms, and provides adapters to popular metrics packages, like expvar, statsd, and Prometheus.

Rationale

TODO

Usage

A simple counter, exported via expvar.

import "github.com/go-kit/kit/metrics/expvar"

func main() {
	myCount := expvar.NewCounter("my_count")
	myCount.Add(1)
}

A histogram for request duration, exported via a Prometheus summary with dynamically-computed quantiles.

import (
	stdprometheus "github.com/prometheus/client_golang/prometheus"

	"github.com/go-kit/kit/metrics"
	"github.com/go-kit/kit/metrics/prometheus"
)

var requestDuration = prometheus.NewSummary(stdprometheus.SummaryOpts{
	Namespace: "myservice",
	Subsystem: "api",
	Name:      "request_duration_nanoseconds_count",
	Help:      "Total time spent serving requests.",
}, []string{})

func handleRequest() {
	defer func(begin time.Time) { requestDuration.Observe(time.Since(begin)) }(time.Now())
	// handle request
}

A gauge for the number of goroutines currently running, exported via statsd.

import (
	"net"
	"os"
	"runtime"
	"time"

	"github.com/go-kit/kit/metrics/statsd"
)

func main() {
	statsdWriter, err := net.Dial("udp", "127.0.0.1:8126")
	if err != nil {
		os.Exit(1)
	}

	reportingDuration := 5 * time.Second
	goroutines := statsd.NewGauge(statsdWriter, "total_goroutines", reportingDuration)
	for range time.Tick(reportingDuration) {
		goroutines.Set(float64(runtime.NumGoroutine()))
	}
}