From 062443133e84faaf3048499f662e55bcd3b8312b Mon Sep 17 00:00:00 2001
From: Brian Brazil <brian.brazil@boxever.com>
Date: Thu, 5 Jun 2014 16:59:51 +0100
Subject: [PATCH] Add collector for /proc/stat, enabled by default.

This gives cpu stats, boot time, context switches, forks.
---
 collector/stat.go | 156 ++++++++++++++++++++++++++++++++++++++++++++++
 node_exporter.go  |   2 +-
 2 files changed, 157 insertions(+), 1 deletion(-)
 create mode 100644 collector/stat.go

diff --git a/collector/stat.go b/collector/stat.go
new file mode 100644
index 00000000..798fa551
--- /dev/null
+++ b/collector/stat.go
@@ -0,0 +1,156 @@
+// +build !nostat
+
+package collector
+
+import (
+	"bufio"
+	"os"
+	"strconv"
+	"strings"
+
+	"github.com/prometheus/client_golang/prometheus"
+)
+
+const (
+	procStat = "/proc/stat"
+)
+
+var (
+	cpuMetrics         = prometheus.NewCounter()
+	intrMetric         = prometheus.NewCounter()
+	ctxtMetric         = prometheus.NewCounter()
+	btimeMetric        = prometheus.NewGauge()
+	forksMetric        = prometheus.NewCounter()
+	procsRunningMetric = prometheus.NewGauge()
+	procsBlockedMetric = prometheus.NewGauge()
+)
+
+type statCollector struct {
+	registry prometheus.Registry
+	config   Config
+}
+
+func init() {
+	Factories["stat"] = NewStatCollector
+}
+
+// Takes a config struct and prometheus registry and returns a new Collector exposing
+// network device stats.
+func NewStatCollector(config Config, registry prometheus.Registry) (Collector, error) {
+	c := statCollector{
+		config:   config,
+		registry: registry,
+	}
+	registry.Register(
+		"node_cpu",
+		"Seconds the cpus spent in each mode.",
+		prometheus.NilLabels,
+		cpuMetrics,
+	)
+	registry.Register(
+		"node_intr",
+		"Total number of interrupts serviced",
+		prometheus.NilLabels,
+		intrMetric,
+	)
+	registry.Register(
+		"node_context_switches",
+		"Total number of context switches.",
+		prometheus.NilLabels,
+		ctxtMetric,
+	)
+	registry.Register(
+		"node_forks",
+		"Total number of forks.",
+		prometheus.NilLabels,
+		forksMetric,
+	)
+	registry.Register(
+		"node_boot_time",
+		"Node boot time, in unixtime.",
+		prometheus.NilLabels,
+		btimeMetric,
+	)
+	registry.Register(
+		"node_procs_running",
+		"Number of processes in runnable state.",
+		prometheus.NilLabels,
+		procsRunningMetric,
+	)
+	registry.Register(
+		"node_procs_blocked",
+		"Number of processes blocked waiting for I/O to complete.",
+		prometheus.NilLabels,
+		procsBlockedMetric,
+	)
+	return &c, nil
+}
+
+// Expose a variety of stats from /proc/stats.
+func (c *statCollector) Update() (updates int, err error) {
+	file, err := os.Open(procStat)
+	if err != nil {
+		return updates, err
+	}
+	defer file.Close()
+
+	scanner := bufio.NewScanner(file)
+	for scanner.Scan() {
+		parts := strings.Fields(scanner.Text())
+		switch {
+		case strings.HasPrefix(parts[0], "cpu"):
+			// Export only per-cpu stats, it can be aggregted up in prometheus.
+			if parts[0] == "cpu" {
+				break
+			}
+			// Only some of these may be present, depending on kernel version.
+			cpuFields := []string{"user", "nice", "system", "idle", "iowait", "irq", "softirq", "steal", "guest"}
+			for i, v := range parts[1 : len(cpuFields)+1] {
+				value, err := strconv.ParseFloat(v, 64)
+				if err != nil {
+					return updates, err
+				}
+				value /= 100 // Convert from ticks to seconds
+				cpuMetrics.Set(map[string]string{"cpu": parts[0], "mode": cpuFields[i]}, value)
+			}
+		case parts[0] == "intr":
+			// 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
+			}
+			intrMetric.Set(prometheus.NilLabels, value)
+		case parts[0] == "ctxt":
+			value, err := strconv.ParseFloat(parts[1], 64)
+			if err != nil {
+				return updates, err
+			}
+			ctxtMetric.Set(prometheus.NilLabels, value)
+		case parts[0] == "processes":
+			value, err := strconv.ParseFloat(parts[1], 64)
+			if err != nil {
+				return updates, err
+			}
+			forksMetric.Set(prometheus.NilLabels, value)
+		case parts[0] == "btime":
+			value, err := strconv.ParseFloat(parts[1], 64)
+			if err != nil {
+				return updates, err
+			}
+			btimeMetric.Set(prometheus.NilLabels, value)
+		case parts[0] == "procs_running":
+			value, err := strconv.ParseFloat(parts[1], 64)
+			if err != nil {
+				return updates, err
+			}
+			procsRunningMetric.Set(prometheus.NilLabels, value)
+		case parts[0] == "procs_blocked":
+			value, err := strconv.ParseFloat(parts[1], 64)
+			if err != nil {
+				return updates, err
+			}
+			procsBlockedMetric.Set(prometheus.NilLabels, value)
+		}
+	}
+	return updates, err
+}
diff --git a/node_exporter.go b/node_exporter.go
index 4101aeb3..ded1a4dc 100644
--- a/node_exporter.go
+++ b/node_exporter.go
@@ -25,7 +25,7 @@ var (
 	configFile        = flag.String("config", "node_exporter.conf", "config file.")
 	memProfile        = flag.String("memprofile", "", "write memory profile to this file")
 	listeningAddress  = flag.String("listen", ":8080", "address to listen on")
-	enabledCollectors = flag.String("enabledCollectors", "attributes,diskstats,filesystem,loadavg,meminfo,netdev", "comma-seperated list of collectors to use")
+	enabledCollectors = flag.String("enabledCollectors", "attributes,diskstats,filesystem,loadavg,meminfo,stat,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")
 	scrapeDurations   = prometheus.NewDefaultHistogram()