translate.go

package main

import (
	"log"
	"net/http"

	"github.com/prometheus/client_golang/prometheus"
	"github.com/prometheus/client_golang/prometheus/promhttp"
	dto "github.com/prometheus/client_model/go"
	"github.com/prometheus/common/promlog"
	"github.com/prometheus/exporter-toolkit/web"
)

type TranslatingGatherer struct {
	prometheus.Gatherer

	translations map[string]string
}

func (g TranslatingGatherer) Gather() ([]*dto.MetricFamily, error) {
	mfs, err := g.Gatherer.Gather()
	if err != nil {
		return nil, err
	}
	for i, mf := range mfs {
		v, ok := g.translations[*mf.Name]
		if ok {
			mf.Name = &v
		}
	}
	return mfs, nil
}

var (
	cpuTemp = prometheus.NewGauge(prometheus.GaugeOpts{
		Name: "cpu_temperature_current",
		Help: "Current temperature of the CPU.",
	})
	hdFailures = prometheus.NewCounterVec(
		prometheus.CounterOpts{
			Name: "disk_errors_total",
			Help: "Number of hard-disk errors.",
		},
		[]string{"device"},
	)
)

func main() {
	var (
		registry = prometheus.NewRegistry()

		mux    = http.NewServeMux()
		server = http.Server{Handler: mux, Addr: ":8080"}
		logger = promlog.New(&promlog.Config{})

		v1 = TranslatingGatherer{registry, map[string]string{
			"cpu_temperature_current": "cpu_temperature_celsius",
			"disk_errors_total":       "hd_errors_total",
		}}
		v2alpha1 = registry
	)

	cpuTemp.Set(23.5)
	hdFailures.With(prometheus.Labels{"device": "/dev/sda"}).Add(42)

	registry.MustRegister(cpuTemp)
	registry.MustRegister(hdFailures)
	mux.Handle("/metrics/v1", promhttp.HandlerFor(v1, promhttp.HandlerOpts{}))
	mux.Handle("/metrics/v2alpha1", promhttp.HandlerFor(v2alpha1, promhttp.HandlerOpts{}))

	if err := web.ListenAndServe(&server, "", logger); err != nil {
		log.Fatal(err)
	}
}