prometheus

package main

import (
   "log"
   "net/http"

   "github.com/prometheus/client_golang/prometheus"
   "github.com/prometheus/client_golang/prometheus/promhttp"
)

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

func init() {
   // Metrics have to be registered to be exposed:
   prometheus.Register(cpuTemp)
   prometheus.MustRegister(hdFailures)
}

func main() {
   cpuTemp.Set(65.3)
   hdFailures.With(prometheus.Labels{"device": "/dev/sda"}).Inc()

   // The Handler function provides a default handler to expose metrics
   // via an HTTP server. "/metrics" is the usual endpoint for that.
   http.Handle("/metrics", promhttp.Handler())
   log.Fatal(http.ListenAndServe(":8888", nil))
}