prometheus-disk-usage-exporter

prom-serve.go

package main

import (
	"fmt"
	"log"
	"os/exec"
	"bufio"
	"strings"
	"strconv"
	"net/http"
	"time"

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

var (
	diskSize = prometheus.NewGauge(prometheus.GaugeOpts{
		Name:        "disk_size_devadap1",
		Help:        "disk size first partition",
		ConstLabels: prometheus.Labels{"version": "1234"},
	})
	diskAvail = prometheus.NewGauge(prometheus.GaugeOpts{
		Name:        "disk_avail_devadap1",
		Help:        "disk avail first partition",
		ConstLabels: prometheus.Labels{"version": "1234"},
	})
	diskUsed = prometheus.NewGauge(prometheus.GaugeOpts{
		Name:        "disk_used_devadap1",
		Help:        "disk used first partition",
		ConstLabels: prometheus.Labels{"version": "1234"},
	})
	diskCap = prometheus.NewGauge(prometheus.GaugeOpts{
		Name:        "disk_cap_devadap1",
		Help:        "disk capacity first partition",
		ConstLabels: prometheus.Labels{"version": "1234"},
	})
)
const (
	gb = 1024.0 * 1024
	debug = 0
)
func init() {
	prometheus.MustRegister(diskSize)
	prometheus.MustRegister(diskAvail)
	prometheus.MustRegister(diskUsed)
	prometheus.MustRegister(diskCap)
}
type Disk struct {
	FileSystem string
	Size	float64
	Used	float64
	Available float64
	Capacity float64
	MountedOn string
}
func checkerr(err error) {
	if err != nil {
		log.Fatal(err)
	}
}

func getDiskMetrics() (disks []Disk)  {
	disks = make([]Disk, 10)
	cmd := exec.Command("df", "-k")
//	cmd.Stdin = strings.NewReader("some input")
//	var out bytes.Buffer
//	cmd.Stdout = &out
	out, err := cmd.StdoutPipe()
	if err != nil {
		panic(err)
	}
	err = cmd.Start()
	if err != nil {
		log.Fatal(err)
	}
	scanner := bufio.NewScanner(out)
	entry :=0
	for scanner.Scan() {
		fields := strings.Fields(scanner.Text())
		fmt.Println(fields)
		if entry==0 &&  fields[1] != "1024-blocks" {
			log.Fatal("wrong Size field")
		} else if entry>0 {
			s, err := strconv.ParseFloat(fields[1], 64)
			checkerr(err)
			u, err := strconv.ParseFloat(fields[2], 64)
			checkerr(err)
			a, err := strconv.ParseFloat(fields[3], 64)
			checkerr(err)
			disks[entry] = Disk{
				FileSystem: fields[0],
				Size: s,
				Used: u,
				Available: a,
				Capacity: (u/(a+u)),
				MountedOn: fields[5],
			}
		}
		entry++
	}
	err = cmd.Wait()
	if err != nil {
		panic(err)
	}
	if debug == 1 {
		for i:=1;i<entry;i++ {
			fmt.Printf("Filesystem: %s Size: %4.2f Used: %4.2f Avail: %4.2f Cap: %4.2f%%\n", disks[i].FileSystem, disks[i].Size/gb, disks[i].Used/gb, disks[1].Available/gb, disks[i].Capacity*100)
		}
	}

	return
}
/*
Filesystem     Size    Used   Avail Capacity  Mounted on
/dev/da0s1a     46G    7.8G     34G    19%    /
devfs          1.0K    1.0K      0B   100%    /dev
*/


func main() {
	go func() {
		for {
			d := getDiskMetrics()
			diskSize.Set(d[1].Size/gb)
			diskUsed.Set(d[1].Used/gb)
			diskAvail.Set(d[1].Available/gb)
			diskCap.Set(d[1].Capacity*100)

			time.Sleep(30 * time.Second)
		}
	}()


	http.Handle("/metrics", promhttp.Handler())
	http.ListenAndServe(":8080", nil)
}