Collect at every scrape, rather than at regular intervals.

Switch to Update using the Collecter Collect interface, due to not knowing all
metricnames in all modules beforehand we can't use Describe and thus the full
Collecter interface.

Remove 'updates', it's meaning varies by module and doesn't add much.

collector/attributes.go

@@ -29,7 +29,7 @@ func NewAttributesCollector(config Config) (Collector, error) {
 	for l := range c.config.Attributes {
 		labelNames = append(labelNames, l)
 	}
-	gv := prometheus.NewGaugeVec(
+	attributes = prometheus.NewGaugeVec(
 		prometheus.GaugeOpts{
 			Namespace: Namespace,
 			Name:      "attributes",
@@ -37,17 +37,13 @@ func NewAttributesCollector(config Config) (Collector, error) {
 		},
 		labelNames,
 	)
-	collector, err := prometheus.RegisterOrGet(gv)
-	if err != nil {
-		return nil, err
-	}
-	attributes = collector.(*prometheus.GaugeVec)
 	return &c, nil
 }
 
-func (c *attributesCollector) Update() (updates int, err error) {
+func (c *attributesCollector) Update(ch chan<- prometheus.Metric) (err error) {
 	glog.V(1).Info("Set node_attributes{%v}: 1", c.config.Attributes)
 	attributes.Reset()
 	attributes.With(c.config.Attributes).Set(1)
-	return updates, err
+	attributes.Collect(ch)
+	return err
 }

collector/bonding.go

@@ -41,29 +41,22 @@ func init() {
 // It exposes the number of configured and active slave of linux bonding interfaces.
 func NewBondingCollector(config Config) (Collector, error) {
 	c := bondingCollector{}
-	if _, err := prometheus.RegisterOrGet(bondingSlaves); err != nil {
-		return nil, err
-	}
-	if _, err := prometheus.RegisterOrGet(bondingSlavesActive); err != nil {
-		return nil, err
-	}
 	return &c, nil
 }
 
 // Update reads and exposes bonding states, implements Collector interface. Caution: This works only on linux.
-func (c *bondingCollector) Update() (int, error) {
+func (c *bondingCollector) Update(ch chan<- prometheus.Metric) (err error) {
 	bondingStats, err := readBondingStats(sysfsNet)
 	if err != nil {
-		return 0, err
+		return err
 	}
-	updates := 0
 	for master, status := range bondingStats {
 		bondingSlaves.WithLabelValues(master).Set(float64(status[0]))
-		updates++
 		bondingSlavesActive.WithLabelValues(master).Set(float64(status[1]))
-		updates++
 	}
-	return updates, nil
+	bondingSlaves.Collect(ch)
+	bondingSlavesActive.Collect(ch)
+	return nil
 }
 
 func readBondingStats(root string) (status map[string][2]int, err error) {

collector/collector.go

@@ -1,6 +1,10 @@
 // Exporter is a prometheus exporter using multiple Factories to collect and export system metrics.
 package collector
 
+import (
+	"github.com/prometheus/client_golang/prometheus"
+)
+
 const Namespace = "node"
 
 var Factories = make(map[string]func(Config) (Collector, error))
@@ -8,7 +12,7 @@ var Factories = make(map[string]func(Config) (Collector, error))
 // Interface a collector has to implement.
 type Collector interface {
 	// Get new metrics and expose them via prometheus registry.
-	Update() (n int, err error)
+	Update(ch chan<- prometheus.Metric) (err error)
 }
 
 // TODO: Instead of periodically call Update, a Collector could be implemented

collector/diskstats.go

@@ -146,19 +146,13 @@ func NewDiskstatsCollector(config Config) (Collector, error) {
 		config:                config,
 		ignoredDevicesPattern: regexp.MustCompile(*ignoredDevices),
 	}
-
-	for _, c := range diskStatsMetrics {
-		if _, err := prometheus.RegisterOrGet(c); err != nil {
-			return nil, err
-		}
-	}
 	return &c, nil
 }
 
-func (c *diskstatsCollector) Update() (updates int, err error) {
+func (c *diskstatsCollector) Update(ch chan<- prometheus.Metric) (err error) {
 	diskStats, err := getDiskStats()
 	if err != nil {
-		return updates, fmt.Errorf("Couldn't get diskstats: %s", err)
+		return fmt.Errorf("Couldn't get diskstats: %s", err)
 	}
 	for dev, stats := range diskStats {
 		if c.ignoredDevicesPattern.MatchString(dev) {
@@ -166,10 +160,9 @@ func (c *diskstatsCollector) Update() (updates int, err error) {
 			continue
 		}
 		for k, value := range stats {
-			updates++
 			v, err := strconv.ParseFloat(value, 64)
 			if err != nil {
-				return updates, fmt.Errorf("Invalid value %s in diskstats: %s", value, err)
+				return fmt.Errorf("Invalid value %s in diskstats: %s", value, err)
 			}
 			counter, ok := diskStatsMetrics[k].(*prometheus.CounterVec)
 			if ok {
@@ -180,7 +173,10 @@ func (c *diskstatsCollector) Update() (updates int, err error) {
 			}
 		}
 	}
-	return updates, err
+	for _, c := range diskStatsMetrics {
+		c.Collect(ch)
+	}
+	return err
 }
 
 func getDiskStats() (map[string]map[int]string, error) {

collector/filesystem.go

@@ -88,29 +88,14 @@ func NewFilesystemCollector(config Config) (Collector, error) {
 		config: config,
 		ignoredMountPointsPattern: regexp.MustCompile(*ignoredMountPoints),
 	}
-	if _, err := prometheus.RegisterOrGet(fsSizeMetric); err != nil {
-		return nil, err
-	}
-	if _, err := prometheus.RegisterOrGet(fsFreeMetric); err != nil {
-		return nil, err
-	}
-	if _, err := prometheus.RegisterOrGet(fsAvailMetric); err != nil {
-		return nil, err
-	}
-	if _, err := prometheus.RegisterOrGet(fsFilesMetric); err != nil {
-		return nil, err
-	}
-	if _, err := prometheus.RegisterOrGet(fsFilesFreeMetric); err != nil {
-		return nil, err
-	}
 	return &c, nil
 }
 
 // Expose filesystem fullness.
-func (c *filesystemCollector) Update() (updates int, err error) {
+func (c *filesystemCollector) Update(ch chan<- prometheus.Metric) (err error) {
 	mps, err := mountPoints()
 	if err != nil {
-		return updates, err
+		return err
 	}
 	for _, mp := range mps {
 		if c.ignoredMountPointsPattern.MatchString(mp) {
@@ -120,16 +105,20 @@ func (c *filesystemCollector) Update() (updates int, err error) {
 		buf := new(syscall.Statfs_t)
 		err := syscall.Statfs(mp, buf)
 		if err != nil {
-			return updates, fmt.Errorf("Statfs on %s returned %s", mp, err)
+			return fmt.Errorf("Statfs on %s returned %s", mp, err)
 		}
 		fsSizeMetric.WithLabelValues(mp).Set(float64(buf.Blocks) * float64(buf.Bsize))
 		fsFreeMetric.WithLabelValues(mp).Set(float64(buf.Bfree) * float64(buf.Bsize))
 		fsAvailMetric.WithLabelValues(mp).Set(float64(buf.Bavail) * float64(buf.Bsize))
 		fsFilesMetric.WithLabelValues(mp).Set(float64(buf.Files))
 		fsFilesFreeMetric.WithLabelValues(mp).Set(float64(buf.Ffree))
-		updates++
 	}
-	return updates, err
+	fsSizeMetric.Collect(ch)
+	fsFreeMetric.Collect(ch)
+	fsAvailMetric.Collect(ch)
+	fsFilesMetric.Collect(ch)
+	fsFilesFreeMetric.Collect(ch)
+	return err
 }
 
 func mountPoints() ([]string, error) {

collector/gmond_collector.go

@@ -68,17 +68,16 @@ func (c *gmondCollector) setMetric(name, cluster string, metric ganglia.Metric)
 			},
 			[]string{"cluster"},
 		)
-		c.Metrics[name] = prometheus.MustRegisterOrGet(gv).(*prometheus.GaugeVec)
 	}
 	glog.V(1).Infof("Set %s{cluster=%q}: %f", name, cluster, metric.Value)
 	c.Metrics[name].WithLabelValues(cluster).Set(metric.Value)
 }
 
-func (c *gmondCollector) Update() (updates int, err error) {
+func (c *gmondCollector) Update(ch chan<- prometheus.Metric) (err error) {
 	conn, err := net.Dial(gangliaProto, gangliaAddress)
 	glog.V(1).Infof("gmondCollector Update")
 	if err != nil {
-		return updates, fmt.Errorf("Can't connect to gmond: %s", err)
+		return fmt.Errorf("Can't connect to gmond: %s", err)
 	}
 	conn.SetDeadline(time.Now().Add(gangliaTimeout))
 
@@ -88,7 +87,7 @@ func (c *gmondCollector) Update() (updates int, err error) {
 
 	err = decoder.Decode(&ganglia)
 	if err != nil {
-		return updates, fmt.Errorf("Couldn't parse xml: %s", err)
+		return fmt.Errorf("Couldn't parse xml: %s", err)
 	}
 
 	for _, cluster := range ganglia.Clusters {
@@ -98,11 +97,13 @@ func (c *gmondCollector) Update() (updates int, err error) {
 				name := illegalCharsRE.ReplaceAllString(metric.Name, "_")
 
 				c.setMetric(name, cluster.Name, metric)
-				updates++
 			}
 		}
 	}
-	return updates, err
+	for _, m := range c.Metrics {
+		m.Collect(ch)
+	}
+	return err
 }
 
 func toUtf8(charset string, input io.Reader) (io.Reader, error) {

collector/interrupts.go

@@ -42,23 +42,19 @@ func NewInterruptsCollector(config Config) (Collector, error) {
 	c := interruptsCollector{
 		config: config,
 	}
-	if _, err := prometheus.RegisterOrGet(interruptsMetric); err != nil {
-		return nil, err
-	}
 	return &c, nil
 }
 
-func (c *interruptsCollector) Update() (updates int, err error) {
+func (c *interruptsCollector) Update(ch chan<- prometheus.Metric) (err error) {
 	interrupts, err := getInterrupts()
 	if err != nil {
-		return updates, fmt.Errorf("Couldn't get interrupts: %s", err)
+		return fmt.Errorf("Couldn't get interrupts: %s", err)
 	}
 	for name, interrupt := range interrupts {
 		for cpuNo, value := range interrupt.values {
-			updates++
 			fv, err := strconv.ParseFloat(value, 64)
 			if err != nil {
-				return updates, fmt.Errorf("Invalid value %s in interrupts: %s", value, err)
+				return fmt.Errorf("Invalid value %s in interrupts: %s", value, err)
 			}
 			labels := prometheus.Labels{
 				"CPU":     strconv.Itoa(cpuNo),
@@ -69,7 +65,8 @@ func (c *interruptsCollector) Update() (updates int, err error) {
 			interruptsMetric.With(labels).Set(fv)
 		}
 	}
-	return updates, err
+	interruptsMetric.Collect(ch)
+	return err
 }
 
 type interrupt struct {

collector/lastlogin.go

@@ -39,21 +39,18 @@ func NewLastLoginCollector(config Config) (Collector, error) {
 	c := lastLoginCollector{
 		config: config,
 	}
-	if _, err := prometheus.RegisterOrGet(lastSeen); err != nil {
-		return nil, err
-	}
 	return &c, nil
 }
 
-func (c *lastLoginCollector) Update() (updates int, err error) {
+func (c *lastLoginCollector) Update(ch chan<- prometheus.Metric) (err error) {
 	last, err := getLastLoginTime()
 	if err != nil {
-		return updates, fmt.Errorf("Couldn't get last seen: %s", err)
+		return fmt.Errorf("Couldn't get last seen: %s", err)
 	}
-	updates++
 	glog.V(1).Infof("Set node_last_login_time: %f", last)
 	lastSeen.Set(last)
-	return updates, err
+	lastSeen.Collect(ch)
+	return err
 }
 
 func getLastLoginTime() (float64, error) {

collector/loadavg.go

@@ -38,23 +38,18 @@ func NewLoadavgCollector(config Config) (Collector, error) {
 	c := loadavgCollector{
 		config: config,
 	}
-
-	if _, err := prometheus.RegisterOrGet(load1); err != nil {
-		return nil, err
-	}
 	return &c, nil
 }
 
-func (c *loadavgCollector) Update() (updates int, err error) {
+func (c *loadavgCollector) Update(ch chan<- prometheus.Metric) (err error) {
 	load, err := getLoad1()
 	if err != nil {
-		return updates, fmt.Errorf("Couldn't get load: %s", err)
+		return fmt.Errorf("Couldn't get load: %s", err)
 	}
-	updates++
 	glog.V(1).Infof("Set node_load: %f", load)
 	load1.Set(load)
-
-	return updates, err
+	load1.Collect(ch)
+	return err
 }
 
 func getLoad1() (float64, error) {

collector/megacli.go

@@ -130,104 +130,92 @@ func NewMegaCliCollector(config Config) (Collector, error) {
 		config: config,
 		cli:    cli,
 	}
-
-	if _, err := prometheus.RegisterOrGet(driveTemperature); err != nil {
-		return nil, err
-	}
-	if _, err := prometheus.RegisterOrGet(driveCounters); err != nil {
-		return nil, err
-	}
-	if _, err := prometheus.RegisterOrGet(drivePresence); err != nil {
-		return nil, err
-	}
 	return &c, nil
 }
 
-func (c *megaCliCollector) Update() (updates int, err error) {
-	au, err := c.updateAdapter()
+func (c *megaCliCollector) Update(ch chan<- prometheus.Metric) (err error) {
+	err = c.updateAdapter()
 	if err != nil {
-		return au, err
+		return err
 	}
-	du, err := c.updateDisks()
-	return au + du, err
+	err = c.updateDisks()
+	driveTemperature.Collect(ch)
+	driveCounters.Collect(ch)
+	drivePresence.Collect(ch)
+	return err
 }
 
-func (c *megaCliCollector) updateAdapter() (int, error) {
+func (c *megaCliCollector) updateAdapter() error {
 	cmd := exec.Command(c.cli, "-AdpAllInfo", "-aALL")
 	pipe, err := cmd.StdoutPipe()
 	if err != nil {
-		return 0, err
+		return err
 	}
 
 	if err := cmd.Start(); err != nil {
-		return 0, err
+		return err
 	}
 
 	stats, err := parseMegaCliAdapter(pipe)
 	if err != nil {
-		return 0, err
+		return err
 	}
 	if err := cmd.Wait(); err != nil {
-		return 0, err
+		return err
 	}
 
-	updates := 0
 	for k, v := range stats["Device Present"] {
 		value, err := strconv.ParseFloat(v, 64)
 		if err != nil {
-			return updates, err
+			return err
 		}
 		drivePresence.WithLabelValues(k).Set(value)
-		updates++
 	}
-	return updates, nil
+	return nil
 }
 
-func (c *megaCliCollector) updateDisks() (int, error) {
+func (c *megaCliCollector) updateDisks() error {
 	cmd := exec.Command(c.cli, "-PDList", "-aALL")
 	pipe, err := cmd.StdoutPipe()
 	if err != nil {
-		return 0, err
+		return err
 	}
 
 	if err := cmd.Start(); err != nil {
-		return 0, err
+		return err
 	}
 
 	stats, err := parseMegaCliDisks(pipe)
 	if err != nil {
-		return 0, err
+		return err
 	}
 	if err := cmd.Wait(); err != nil {
-		return 0, err
+		return err
 	}
 
-	updates := 0
 	for enc, encStats := range stats {
 		for slot, slotStats := range encStats {
 			tStr := slotStats["Drive Temperature"]
 			tStr = tStr[:strings.Index(tStr, "C")]
 			t, err := strconv.ParseFloat(tStr, 64)
 			if err != nil {
-				return updates, err
+				return err
 			}
 
 			encStr := strconv.Itoa(enc)
 			slotStr := strconv.Itoa(slot)
 
 			driveTemperature.WithLabelValues(encStr, slotStr).Set(t)
-			updates++
 
 			for _, c := range counters {
 				counter, err := strconv.ParseFloat(slotStats[c], 64)
 				if err != nil {
-					return updates, err
+					return err
 				}
 
 				driveCounters.WithLabelValues(encStr, slotStr, c).Set(counter)
-				updates++
 			}
 		}
 	}
-	return updates, nil
+	return nil
 }

collector/meminfo.go

@@ -41,26 +41,25 @@ func NewMeminfoCollector(config Config) (Collector, error) {
 	return &c, nil
 }
 
-func (c *meminfoCollector) Update() (updates int, err error) {
+func (c *meminfoCollector) Update(ch chan<- prometheus.Metric) (err error) {
 	memInfo, err := getMemInfo()
 	if err != nil {
-		return updates, fmt.Errorf("Couldn't get meminfo: %s", err)
+		return fmt.Errorf("Couldn't get meminfo: %s", err)
 	}
 	glog.V(1).Infof("Set node_mem: %#v", memInfo)
 	for k, v := range memInfo {
 		if _, ok := memInfoMetrics[k]; !ok {
-			gauge := prometheus.NewGauge(prometheus.GaugeOpts{
+			memInfoMetrics[k] = prometheus.NewGauge(prometheus.GaugeOpts{
 				Namespace: Namespace,
 				Subsystem: memInfoSubsystem,
 				Name:      k,
 				Help:      k + " from /proc/meminfo.",
 			})
-			memInfoMetrics[k] = prometheus.MustRegisterOrGet(gauge).(prometheus.Gauge)
 		}
-		updates++
 		memInfoMetrics[k].Set(v)
+		memInfoMetrics[k].Collect(ch)
 	}
-	return updates, err
+	return err
 }
 
 func getMemInfo() (map[string]float64, error) {

collector/netdev.go

@@ -39,17 +39,17 @@ func NewNetDevCollector(config Config) (Collector, error) {
 	return &c, nil
 }
 
-func (c *netDevCollector) Update() (updates int, err error) {
+func (c *netDevCollector) Update(ch chan<- prometheus.Metric) (err error) {
 	netStats, err := getNetStats()
 	if err != nil {
-		return updates, fmt.Errorf("Couldn't get netstats: %s", err)
+		return fmt.Errorf("Couldn't get netstats: %s", err)
 	}
 	for direction, devStats := range netStats {
 		for dev, stats := range devStats {
 			for t, value := range stats {
 				key := direction + "_" + t
 				if _, ok := netStatsMetrics[key]; !ok {
-					gv := prometheus.NewGaugeVec(
+					netStatsMetrics[key] = prometheus.NewGaugeVec(
 						prometheus.GaugeOpts{
 							Namespace: Namespace,
 							Subsystem: netStatsSubsystem,
@@ -58,18 +58,19 @@ func (c *netDevCollector) Update() (updates int, err error) {
 						},
 						[]string{"device"},
 					)
-					netStatsMetrics[key] = prometheus.MustRegisterOrGet(gv).(*prometheus.GaugeVec)
 				}
-				updates++
 				v, err := strconv.ParseFloat(value, 64)
 				if err != nil {
-					return updates, fmt.Errorf("Invalid value %s in netstats: %s", value, err)
+					return fmt.Errorf("Invalid value %s in netstats: %s", value, err)
 				}
 				netStatsMetrics[key].WithLabelValues(dev).Set(v)
 			}
 		}
 	}
-	return updates, err
+	for _, m := range netStatsMetrics {
+		m.Collect(ch)
+	}
+	return err
 }
 
 func getNetStats() (map[string]map[string]map[string]string, error) {

collector/ntp.go

@@ -36,21 +36,17 @@ func NewNtpCollector(config Config) (Collector, error) {
 	}
 	c := ntpCollector{}
 
-	if _, err := prometheus.RegisterOrGet(ntpDrift); err != nil {
-		return nil, err
-	}
 	return &c, nil
 }
 
-func (c *ntpCollector) Update() (updates int, err error) {
+func (c *ntpCollector) Update(ch chan<- prometheus.Metric) (err error) {
 	t, err := ntp.Time(*ntpServer)
 	if err != nil {
-		return updates, fmt.Errorf("Couldn't get ntp drift: %s", err)
+		return fmt.Errorf("Couldn't get ntp drift: %s", err)
 	}
 	drift := t.Sub(time.Now())
-	updates++
 	glog.V(1).Infof("Set ntp_drift_seconds: %f", drift.Seconds())
 	ntpDrift.Set(drift.Seconds())
-
-	return updates, err
+	ntpDrift.Collect(ch)
+	return err
 }

collector/runit_collector.go

@@ -50,23 +50,13 @@ func NewRunitCollector(config Config) (Collector, error) {
 		config: config,
 	}
 
-	if _, err := prometheus.RegisterOrGet(runitState); err != nil {
-		return nil, err
-	}
-	if _, err := prometheus.RegisterOrGet(runitStateDesired); err != nil {
-		return nil, err
-	}
-	if _, err := prometheus.RegisterOrGet(runitStateNormal); err != nil {
-		return nil, err
-	}
-
 	return &c, nil
 }
 
-func (c *runitCollector) Update() (updates int, err error) {
+func (c *runitCollector) Update(ch chan<- prometheus.Metric) (err error) {
 	services, err := runit.GetServices("/etc/service")
 	if err != nil {
-		return 0, err
+		return err
 	}
 
 	for _, service := range services {
@@ -84,8 +74,9 @@ func (c *runitCollector) Update() (updates int, err error) {
 		} else {
 			runitStateNormal.WithLabelValues(service.Name).Set(1)
 		}
-		updates += 3
 	}
-
-	return updates, err
+	runitState.Collect(ch)
+	runitStateDesired.Collect(ch)
+	runitStateNormal.Collect(ch)
+	return err
 }

collector/stat.go

@@ -73,35 +73,14 @@ func NewStatCollector(config Config) (Collector, error) {
 	c := statCollector{
 		config: config,
 	}
-	if _, err := prometheus.RegisterOrGet(cpuMetrics); err != nil {
-		return nil, err
-	}
-	if _, err := prometheus.RegisterOrGet(intrMetric); err != nil {
-		return nil, err
-	}
-	if _, err := prometheus.RegisterOrGet(ctxtMetric); err != nil {
-		return nil, err
-	}
-	if _, err := prometheus.RegisterOrGet(forksMetric); err != nil {
-		return nil, err
-	}
-	if _, err := prometheus.RegisterOrGet(btimeMetric); err != nil {
-		return nil, err
-	}
-	if _, err := prometheus.RegisterOrGet(procsRunningMetric); err != nil {
-		return nil, err
-	}
-	if _, err := prometheus.RegisterOrGet(procsBlockedMetric); err != nil {
-		return nil, err
-	}
 	return &c, nil
 }
 
 // Expose a variety of stats from /proc/stats.
-func (c *statCollector) Update() (updates int, err error) {
+func (c *statCollector) Update(ch chan<- prometheus.Metric) (err error) {
 	file, err := os.Open(procStat)
 	if err != nil {
-		return updates, err
+		return err
 	}
 	defer file.Close()
 
@@ -119,7 +98,7 @@ func (c *statCollector) Update() (updates int, err error) {
 			for i, v := range parts[1 : len(cpuFields)+1] {
 				value, err := strconv.ParseFloat(v, 64)
 				if err != nil {
-					return updates, err
+					return err
 				}
 				// Convert from ticks to seconds
 				value /= float64(C.sysconf(C._SC_CLK_TCK))
@@ -129,40 +108,47 @@ func (c *statCollector) Update() (updates int, err error) {
 			// Only expose the overall number, use the 'interrupts' collector for more detail.
 			value, err := strconv.ParseFloat(parts[1], 64)
 			if err != nil {
-				return updates, err
+				return err
 			}
 			intrMetric.Set(value)
 		case parts[0] == "ctxt":
 			value, err := strconv.ParseFloat(parts[1], 64)
 			if err != nil {
-				return updates, err
+				return err
 			}
 			ctxtMetric.Set(value)
 		case parts[0] == "processes":
 			value, err := strconv.ParseFloat(parts[1], 64)
 			if err != nil {
-				return updates, err
+				return err
 			}
 			forksMetric.Set(value)
 		case parts[0] == "btime":
 			value, err := strconv.ParseFloat(parts[1], 64)
 			if err != nil {
-				return updates, err
+				return err
 			}
 			btimeMetric.Set(value)
 		case parts[0] == "procs_running":
 			value, err := strconv.ParseFloat(parts[1], 64)
 			if err != nil {
-				return updates, err
+				return err
 			}
 			procsRunningMetric.Set(value)
 		case parts[0] == "procs_blocked":
 			value, err := strconv.ParseFloat(parts[1], 64)
 			if err != nil {
-				return updates, err
+				return err
 			}
 			procsBlockedMetric.Set(value)
 		}
 	}
-	return updates, err
+	cpuMetrics.Collect(ch)
+	ctxtMetric.Collect(ch)
+	intrMetric.Collect(ch)
+	forksMetric.Collect(ch)
+	btimeMetric.Collect(ch)
+	procsRunningMetric.Collect(ch)
+	procsBlockedMetric.Collect(ch)
+	return err
 }

collector/time.go

@@ -32,16 +32,13 @@ func NewTimeCollector(config Config) (Collector, error) {
 		config: config,
 	}
 
-	if _, err := prometheus.RegisterOrGet(systemTime); err != nil {
-		return nil, err
-	}
 	return &c, nil
 }
 
-func (c *timeCollector) Update() (updates int, err error) {
-	updates++
+func (c *timeCollector) Update(ch chan<- prometheus.Metric) (err error) {
 	now := time.Now()
 	glog.V(1).Infof("Set time: %f", now.Unix())
 	systemTime.Set(float64(now.Unix()))
-	return updates, err
+	systemTime.Collect(ch)
+	return err
 }

node_exporter.go

@@ -28,7 +28,6 @@ var (
 	listeningAddress  = flag.String("listen", ":8080", "address to listen on")
 	enabledCollectors = flag.String("enabledCollectors", "attributes,diskstats,filesystem,loadavg,meminfo,stat,time,netdev", "comma-seperated list of collectors to use")
 	printCollectors   = flag.Bool("printCollectors", false, "If true, print available collectors and exit")
-	interval          = flag.Duration("interval", 60*time.Second, "refresh interval")
 
 	collectorLabelNames = []string{"collector", "result"}
 
@@ -41,78 +40,56 @@ var (
 		},
 		collectorLabelNames,
 	)
-	metricsUpdated = prometheus.NewGaugeVec(
-		prometheus.GaugeOpts{
-			Namespace: collector.Namespace,
-			Subsystem: subsystem,
-			Name:      "metrics_updated",
-			Help:      "node_exporter: Number of metrics updated.",
-		},
-		collectorLabelNames,
-	)
 )
 
-func main() {
-	flag.Parse()
-	if *printCollectors {
-		fmt.Printf("Available collectors:\n")
-		for n, _ := range collector.Factories {
-			fmt.Printf(" - %s\n", n)
-		}
-		return
+// Implements Collector.
+type NodeCollector struct {
+	collectors map[string]collector.Collector
+}
+
+// Implements Collector.
+func (n NodeCollector) Describe(ch chan<- *prometheus.Desc) {
+	scrapeDurations.Describe(ch)
+}
+
+// Implements Collector.
+func (n NodeCollector) Collect(ch chan<- prometheus.Metric) {
+	wg := sync.WaitGroup{}
+	wg.Add(len(n.collectors))
+	for name, c := range n.collectors {
+		go func(name string, c collector.Collector) {
+			Execute(name, c, ch)
+			wg.Done()
+		}(name, c)
 	}
-	collectors, err := loadCollectors(*configFile)
+	wg.Wait()
+	scrapeDurations.Collect(ch)
+}
+
+func Execute(name string, c collector.Collector, ch chan<- prometheus.Metric) {
+	begin := time.Now()
+	err := c.Update(ch)
+	duration := time.Since(begin)
+	var result string
+
 	if err != nil {
-		log.Fatalf("Couldn't load config and collectors: %s", err)
+		glog.Infof("ERROR: %s failed after %fs: %s", name, duration.Seconds(), err)
+		result = "error"
+	} else {
+		glog.Infof("OK: %s success after %fs.", name, duration.Seconds())
+		result = "success"
 	}
+	scrapeDurations.WithLabelValues(name, result).Observe(duration.Seconds())
+}
 
-	prometheus.MustRegister(scrapeDurations)
-	prometheus.MustRegister(metricsUpdated)
-
-	glog.Infof("Enabled collectors:")
-	for n, _ := range collectors {
-		glog.Infof(" - %s", n)
+func getConfig(file string) (*collector.Config, error) {
+	config := &collector.Config{}
+	glog.Infof("Reading config %s", *configFile)
+	bytes, err := ioutil.ReadFile(*configFile)
+	if err != nil {
+		return nil, err
 	}
-
-	sigHup := make(chan os.Signal)
-	sigUsr1 := make(chan os.Signal)
-	signal.Notify(sigHup, syscall.SIGHUP)
-	signal.Notify(sigUsr1, syscall.SIGUSR1)
-
-	go serveStatus()
-
-	glog.Infof("Starting initial collection")
-	collect(collectors)
-
-	tick := time.Tick(*interval)
-	for {
-		select {
-		case <-sigHup:
-			collectors, err = loadCollectors(*configFile)
-			if err != nil {
-				log.Fatalf("Couldn't load config and collectors: %s", err)
-			}
-			glog.Infof("Reloaded collectors and config")
-			tick = time.Tick(*interval)
-
-		case <-tick:
-			glog.Infof("Starting new interval")
-			collect(collectors)
-
-		case <-sigUsr1:
-			glog.Infof("got signal")
-			if *memProfile != "" {
-				glog.Infof("Writing memory profile to %s", *memProfile)
-				f, err := os.Create(*memProfile)
-				if err != nil {
-					log.Fatal(err)
-				}
-				pprof.WriteHeapProfile(f)
-				f.Close()
-			}
-		}
-	}
-
+	return config, json.Unmarshal(bytes, &config)
 }
 
 func loadCollectors(file string) (map[string]collector.Collector, error) {
@@ -135,46 +112,50 @@ func loadCollectors(file string) (map[string]collector.Collector, error) {
 	return collectors, nil
 }
 
-func getConfig(file string) (*collector.Config, error) {
-	config := &collector.Config{}
-	glog.Infof("Reading config %s", *configFile)
-	bytes, err := ioutil.ReadFile(*configFile)
+func main() {
+	flag.Parse()
+	if *printCollectors {
+		fmt.Printf("Available collectors:\n")
+		for n, _ := range collector.Factories {
+			fmt.Printf(" - %s\n", n)
+		}
+		return
+	}
+	collectors, err := loadCollectors(*configFile)
 	if err != nil {
-		return nil, err
+		log.Fatalf("Couldn't load config and collectors: %s", err)
 	}
-	return config, json.Unmarshal(bytes, &config)
-}
 
-func serveStatus() {
-	http.Handle("/metrics", prometheus.Handler())
-	http.ListenAndServe(*listeningAddress, nil)
-}
-
-func collect(collectors map[string]collector.Collector) {
-	wg := sync.WaitGroup{}
-	wg.Add(len(collectors))
-	for n, c := range collectors {
-		go func(n string, c collector.Collector) {
-			Execute(n, c)
-			wg.Done()
-		}(n, c)
+	glog.Infof("Enabled collectors:")
+	for n, _ := range collectors {
+		glog.Infof(" - %s", n)
 	}
-	wg.Wait()
-}
 
-func Execute(name string, c collector.Collector) {
-	begin := time.Now()
-	updates, err := c.Update()
-	duration := time.Since(begin)
-	var result string
+	nodeCollector := NodeCollector{collectors: collectors}
+	prometheus.MustRegister(nodeCollector)
 
-	if err != nil {
-		glog.Infof("ERROR: %s failed after %fs: %s", name, duration.Seconds(), err)
-		result = "error"
-	} else {
-		glog.Infof("OK: %s success after %fs.", name, duration.Seconds())
-		result = "success"
+	sigUsr1 := make(chan os.Signal)
+	signal.Notify(sigUsr1, syscall.SIGUSR1)
+
+	go func() {
+		http.Handle("/metrics", prometheus.Handler())
+		http.ListenAndServe(*listeningAddress, nil)
+	}()
+
+	for {
+		select {
+		case <-sigUsr1:
+			glog.Infof("got signal")
+			if *memProfile != "" {
+				glog.Infof("Writing memory profile to %s", *memProfile)
+				f, err := os.Create(*memProfile)
+				if err != nil {
+					log.Fatal(err)
+				}
+				pprof.WriteHeapProfile(f)
+				f.Close()
+			}
+		}
 	}
-	scrapeDurations.WithLabelValues(name, result).Observe(duration.Seconds())
-	metricsUpdated.WithLabelValues(name, result).Set(float64(updates))
+
 }