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

4 files changed, 113 insertions, 1 deletions

diff --git a/collector/filefd_linux.go b/collector/filefd_linux.go
new file mode 100644
index 0000000..47a5064
--- /dev/null
+++ b/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
+}
diff --git a/collector/filefd_linux_test.go b/collector/filefd_linux_test.go
new file mode 100644
index 0000000..31e4811
--- /dev/null
+++ b/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)
+        }
+}
diff --git a/collector/fixtures/file-nr b/collector/fixtures/file-nr
new file mode 100644
index 0000000..d5a4f87
--- /dev/null
+++ b/collector/fixtures/file-nr
@@ -0,0 +1 @@
+1024    0       1631329
diff --git a/node_exporter.go b/node_exporter.go
index 56f2d2d..890e527 100644
--- a/node_exporter.go
+++ b/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.")