node_exporter/collector/sockstat_linux.go

// +build !nosockstat

package collector

import (
	"bufio"
	"fmt"
	"github.com/prometheus/client_golang/prometheus"
	"io"
	"os"
	"strconv"
	"strings"
)

const (
	procSockStat      = "/proc/net/sockstat"
	sockStatSubsystem = "sockstat"
)

// Used for calculating the total memory bytes on TCP and UDP.
var pageSize = os.Getpagesize()

type sockStatCollector struct {
	metrics map[string]prometheus.Gauge
}

func init() {
	Factories[sockStatSubsystem] = NewSockStatCollector
}

// NewSockStatCollector returns a new Collector exposing socket stats.
func NewSockStatCollector() (Collector, error) {
	return &sockStatCollector{
		metrics: map[string]prometheus.Gauge{},
	}, nil
}

func (c *sockStatCollector) Update(ch chan<- prometheus.Metric) (err error) {
	sockStats, err := getSockStats(procSockStat)
	if err != nil {
		return fmt.Errorf("couldn't get sockstats: %s", err)
	}
	for protocol, protocolStats := range sockStats {
		for name, value := range protocolStats {
			key := protocol + "_" + name
			if _, ok := c.metrics[key]; !ok {
				c.metrics[key] = prometheus.NewGauge(
					prometheus.GaugeOpts{
						Namespace: Namespace,
						Subsystem: sockStatSubsystem,
						Name:      key,
						Help:      fmt.Sprintf("%s %s from /proc/net/sockstat.", protocol, name),
					},
				)
			}
			v, err := strconv.ParseFloat(value, 64)
			if err != nil {
				return fmt.Errorf("invalid value %s in sockstats: %s", value, err)
			}
			c.metrics[key].Set(v)
		}
	}
	for _, m := range c.metrics {
		m.Collect(ch)
	}
	return err
}

func getSockStats(fileName string) (map[string]map[string]string, error) {
	file, err := os.Open(fileName)
	if err != nil {
		return nil, err
	}
	defer file.Close()

	return parseSockStats(file, fileName)
}

func parseSockStats(r io.Reader, fileName string) (map[string]map[string]string, error) {
	var (
		sockStat = map[string]map[string]string{}
		scanner  = bufio.NewScanner(r)
	)

	for scanner.Scan() {
		line := strings.Split(string(scanner.Text()), " ")
		// Remove trailing :.
		protocol := line[0][:len(line[0])-1]
		sockStat[protocol] = map[string]string{}

		for i := 1; i < len(line) && i+1 < len(line); i++ {
			sockStat[protocol][line[i]] = line[i+1]
			i++
		}
	}

	/*
	The mem metrics is the count of pages used.
	Multiply the mem metrics by the page size from the kernal to get the number
	of bytes used.

	Update the TCP mem from page count to bytes.
	*/
	pageCount, err := strconv.Atoi(sockStat["TCP"]["mem"])
	if err != nil {
		return nil, fmt.Errorf("invalid value %s in sockstats: %s", sockStat["TCP"]["mem"], err)
	}
	sockStat["TCP"]["mem_bytes"] = strconv.Itoa(pageCount * pageSize)

	// Update the UDP mem from page count to bytes.
	pageCount, err = strconv.Atoi(sockStat["UDP"]["mem"])
	if err != nil {
		return nil, fmt.Errorf("invalid value %s in sockstats: %s", sockStat["UDP"]["mem"], err)
	}
	sockStat["UDP"]["mem_bytes"] = strconv.Itoa(pageCount * pageSize)

	return sockStat, nil
}