Initial implementation of file-nr

Fixed file-nr update function

Fixed file-nr test case

Fixed file-nr test case again

Fixed file-nr separator to tab

Updated file-nr to filenr.

Updated file-nr to filenr.

Fixed file-nr test cases, added comments

Remove reporting the second value from file-nr as it will alwasy be zero in linux 2.6 and greator

Renaming file-nr to filefd

Updated build constraint

Updates and code cleanup for filefd.

Updated enabledCollectors with the correct name for filefd

Fixed filefd test wording

collector/filefd_linux.go

@@ -0,0 +1,84 @@
+// +build !nofilefd
+
+package collector
+
+import (
+	"bufio"
+	"fmt"
+	"github.com/prometheus/client_golang/prometheus"
+	"io"
+	"os"
+	"strconv"
+	"strings"
+)
+
+const (
+	procFileFDStat      = "/proc/sys/fs/file-nr"
+	fileFDStatSubsystem = "filefd"
+)
+
+type fileFDStatCollector struct {
+	metrics map[string]prometheus.Gauge
+}
+
+func init() {
+	Factories[fileFDStatSubsystem] = NewFileFDStatCollector
+}
+
+// NewFileFDStatCollector returns a new Collector exposing file-nr stats.
+func NewFileFDStatCollector() (Collector, error) {
+	return &fileFDStatCollector{
+		metrics: map[string]prometheus.Gauge{},
+	}, nil
+}
+
+func (c *fileFDStatCollector) Update(ch chan<- prometheus.Metric) (err error) {
+	fileFDStat, err := getFileFDStats(procFileFDStat)
+	if err != nil {
+		return fmt.Errorf("couldn't get file-nr: %s", err)
+	}
+	for name, value := range fileFDStat {
+		if _, ok := c.metrics[name]; !ok {
+			c.metrics[name] = prometheus.NewGauge(
+				prometheus.GaugeOpts{
+					Namespace: Namespace,
+					Subsystem: fileFDStatSubsystem,
+					Name:      name,
+					Help:      fmt.Sprintf("filefd %s from %s.", name, procFileFDStat),
+				},
+			)
+			v, err := strconv.ParseFloat(value, 64)
+			if err != nil {
+				return fmt.Errorf("invalid value %s in file-nr: %s", value, err)
+			}
+			c.metrics[name].Set(v)
+		}
+	}
+	for _, m := range c.metrics {
+		m.Collect(ch)
+	}
+	return err
+}
+
+func getFileFDStats(fileName string) (map[string]string, error) {
+	file, err := os.Open(fileName)
+	if err != nil {
+		return nil, err
+	}
+	defer file.Close()
+	return parseFileFDStats(file, fileName)
+}
+
+func parseFileFDStats(r io.Reader, fileName string) (map[string]string, error) {
+	var scanner = bufio.NewScanner(r)
+	scanner.Scan()
+	// The file-nr proc file is separated by tabs, not spaces.
+	line := strings.Split(string(scanner.Text()), "\u0009")
+	var fileFDStat = map[string]string{}
+	// The file-nr proc is only 1 line with 3 values.
+	fileFDStat["allocated"] = line[0]
+	// The second value is skipped as it will alwasy be zero in linux 2.6.
+	fileFDStat["maximum"] = line[2]
+
+	return fileFDStat, nil
+}

collector/filefd_linux_test.go

@@ -0,0 +1,27 @@
+package collector
+
+import (
+	"os"
+	"testing"
+)
+
+func TestFileFDStats(t *testing.T) {
+	file, err := os.Open("fixtures/file-nr")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer file.Close()
+
+	fileFDStats, err := parseFileFDStats(file, fileName)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if want, got := "1024", fileFDStats["allocated"]; want != got {
+		t.Errorf("want filefd allocated %s, got %s", want, got)
+	}
+
+	if want, got := "1631329", fileFDStats["maximum"]; want != got {
+		t.Errorf("want filefd maximum %s, got %s", want, got)
+	}
+}

collector/fixtures/file-nr

@@ -0,0 +1 @@
+1024	0	1631329

node_exporter.go

@@ -28,7 +28,7 @@ var (
 	memProfile        = flag.String("debug.memprofile-file", "", "Write memory profile to this file upon receipt of SIGUSR1.")
 	listenAddress     = flag.String("web.listen-address", ":9100", "Address on which to expose metrics and web interface.")
 	metricsPath       = flag.String("web.telemetry-path", "/metrics", "Path under which to expose metrics.")
-	enabledCollectors = flag.String("collectors.enabled", "diskstats,filesystem,loadavg,meminfo,stat,textfile,time,netdev,netstat,sockstat", "Comma-separated list of collectors to use.")
+	enabledCollectors = flag.String("collectors.enabled", "diskstats,filesystem,loadavg,meminfo,stat,textfile,time,netdev,netstat,sockstat,filefd", "Comma-separated list of collectors to use.")
 	printCollectors   = flag.Bool("collectors.print", false, "If true, print available collectors and exit.")
 	authUser          = flag.String("auth.user", "", "Username for basic auth.")
 	authPass          = flag.String("auth.pass", "", "Password for basic auth.")