From 64affe205bdca5505bf079a413f6ea9f21cfc0fe Mon Sep 17 00:00:00 2001
From: Ian Hansen <ian@supershabam.com>
Date: Mon, 13 Jul 2015 17:18:34 -0600
Subject: [PATCH] Allows netdev devices to be ignored

---
 collector/netdev.go      | 23 +++++++++++++++++------
 collector/netdev_test.go | 11 ++++++++++-
 2 files changed, 27 insertions(+), 7 deletions(-)

diff --git a/collector/netdev.go b/collector/netdev.go
index a630ff16..ee1de005 100644
--- a/collector/netdev.go
+++ b/collector/netdev.go
@@ -4,6 +4,7 @@ package collector
 
 import (
 	"bufio"
+	"flag"
 	"fmt"
 	"io"
 	"os"
@@ -12,6 +13,7 @@ import (
 	"strings"
 
 	"github.com/prometheus/client_golang/prometheus"
+	"github.com/prometheus/log"
 )
 
 const (
@@ -20,10 +22,13 @@ const (
 )
 
 var (
-	fieldSep = regexp.MustCompile("[ :] *")
+	fieldSep             = regexp.MustCompile("[ :] *")
+	netdevIgnoredDevices = flag.String("collector.netdev.ignored-devices", "^$", "Regexp of net devices to ignore for netdev collector.")
 )
 
 type netDevCollector struct {
+	ignoredDevicesPattern *regexp.Regexp
+
 	metrics map[string]*prometheus.GaugeVec
 }
 
@@ -35,12 +40,13 @@ func init() {
 // network device stats.
 func NewNetDevCollector() (Collector, error) {
 	return &netDevCollector{
-		metrics: map[string]*prometheus.GaugeVec{},
+		ignoredDevicesPattern: regexp.MustCompile(*netdevIgnoredDevices),
+		metrics:               map[string]*prometheus.GaugeVec{},
 	}, nil
 }
 
 func (c *netDevCollector) Update(ch chan<- prometheus.Metric) (err error) {
-	netDev, err := getNetDevStats()
+	netDev, err := getNetDevStats(c.ignoredDevicesPattern)
 	if err != nil {
 		return fmt.Errorf("Couldn't get netstats: %s", err)
 	}
@@ -73,17 +79,17 @@ func (c *netDevCollector) Update(ch chan<- prometheus.Metric) (err error) {
 	return err
 }
 
-func getNetDevStats() (map[string]map[string]map[string]string, error) {
+func getNetDevStats(ignore *regexp.Regexp) (map[string]map[string]map[string]string, error) {
 	file, err := os.Open(procNetDev)
 	if err != nil {
 		return nil, err
 	}
 	defer file.Close()
 
-	return parseNetDevStats(file)
+	return parseNetDevStats(file, ignore)
 }
 
-func parseNetDevStats(r io.Reader) (map[string]map[string]map[string]string, error) {
+func parseNetDevStats(r io.Reader, ignore *regexp.Regexp) (map[string]map[string]map[string]string, error) {
 	netDev := map[string]map[string]map[string]string{}
 	netDev["transmit"] = map[string]map[string]string{}
 	netDev["receive"] = map[string]map[string]string{}
@@ -115,6 +121,11 @@ func parseNetDevStats(r io.Reader) (map[string]map[string]map[string]string, err
 		if err != nil {
 			return nil, err
 		}
+
+		if ignore.MatchString(dev) {
+			log.Debugf("Ignoring device: %s", dev)
+			continue
+		}
 		netDev["transmit"][dev] = transmit
 		netDev["receive"][dev] = receive
 	}
diff --git a/collector/netdev_test.go b/collector/netdev_test.go
index 7eb22413..ce60ca3b 100644
--- a/collector/netdev_test.go
+++ b/collector/netdev_test.go
@@ -2,6 +2,7 @@ package collector
 
 import (
 	"os"
+	"regexp"
 	"testing"
 )
 
@@ -12,7 +13,7 @@ func TestNetDevStats(t *testing.T) {
 	}
 	defer file.Close()
 
-	netStats, err := parseNetDevStats(file)
+	netStats, err := parseNetDevStats(file, regexp.MustCompile("^veth"))
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -28,4 +29,12 @@ func TestNetDevStats(t *testing.T) {
 	if want, got := "934", netStats["transmit"]["tun0"]["packets"]; want != got {
 		t.Errorf("want netstat tun0 packets %s, got %s", want, got)
 	}
+
+	if want, got := 6, len(netStats["transmit"]); want != got {
+		t.Errorf("want count of devices to be %d, got %d", want, got)
+	}
+
+	if _, ok := netStats["transmit"]["veth4B09XN"]; ok != false {
+		t.Error("want fixture interface veth4B09XN to not exist, but it does")
+	}
 }