Consolidate collector selection

Remove special tags necessary for gmond and runit collectors. All
collectors get built. Selection of which collectors to use continues to
happen via parameter.

collector/gmond.go

@@ -0,0 +1,111 @@
+// +build !nogmond
+
+package collector
+
+import (
+	"bufio"
+	"encoding/xml"
+	"fmt"
+	"io"
+	"net"
+	"regexp"
+	"time"
+
+	"github.com/golang/glog"
+	"github.com/prometheus/client_golang/prometheus"
+	"github.com/prometheus/node_exporter/collector/ganglia"
+)
+
+const (
+	gangliaAddress       = "127.0.0.1:8649"
+	gangliaProto         = "tcp"
+	gangliaTimeout       = 30 * time.Second
+	gangliaMetricsPrefix = "ganglia_"
+)
+
+type gmondCollector struct {
+	metrics map[string]*prometheus.GaugeVec
+	config  Config
+}
+
+func init() {
+	Factories["gmond"] = NewGmondCollector
+}
+
+var illegalCharsRE = regexp.MustCompile(`[^a-zA-Z0-9_]`)
+
+// Takes a config struct and prometheus registry and returns a new Collector scraping ganglia.
+func NewGmondCollector(config Config) (Collector, error) {
+	c := gmondCollector{
+		config:  config,
+		metrics: map[string]*prometheus.GaugeVec{},
+	}
+
+	return &c, nil
+}
+
+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 fmt.Errorf("Can't connect to gmond: %s", err)
+	}
+	conn.SetDeadline(time.Now().Add(gangliaTimeout))
+
+	ganglia := ganglia.Ganglia{}
+	decoder := xml.NewDecoder(bufio.NewReader(conn))
+	decoder.CharsetReader = toUtf8
+
+	err = decoder.Decode(&ganglia)
+	if err != nil {
+		return fmt.Errorf("Couldn't parse xml: %s", err)
+	}
+
+	for _, cluster := range ganglia.Clusters {
+		for _, host := range cluster.Hosts {
+
+			for _, metric := range host.Metrics {
+				name := illegalCharsRE.ReplaceAllString(metric.Name, "_")
+
+				c.setMetric(name, cluster.Name, metric)
+			}
+		}
+	}
+	for _, m := range c.metrics {
+		m.Collect(ch)
+	}
+	return err
+}
+
+func (c *gmondCollector) setMetric(name, cluster string, metric ganglia.Metric) {
+	if _, ok := c.metrics[name]; !ok {
+		var desc string
+		var title string
+		for _, element := range metric.ExtraData.ExtraElements {
+			switch element.Name {
+			case "DESC":
+				desc = element.Val
+			case "TITLE":
+				title = element.Val
+			}
+			if title != "" && desc != "" {
+				break
+			}
+		}
+		glog.V(1).Infof("Register %s: %s", name, desc)
+		c.metrics[name] = prometheus.NewGaugeVec(
+			prometheus.GaugeOpts{
+				Namespace: gangliaMetricsPrefix,
+				Name:      name,
+				Help:      desc,
+			},
+			[]string{"cluster"},
+		)
+	}
+	glog.V(1).Infof("Set %s{cluster=%q}: %f", name, cluster, metric.Value)
+	c.metrics[name].WithLabelValues(cluster).Set(metric.Value)
+}
+
+func toUtf8(charset string, input io.Reader) (io.Reader, error) {
+	return input, nil //FIXME
+}