Add prometheus_client output module

Adds a client implementation using the prometheus go_client library
that exposes metrics. Currently only supports Gauge type events.

X-Github-Issue: influxdata#306

outputs/all/all.go

@@ -7,4 +7,5 @@ import (
 	_ "github.com/influxdb/telegraf/outputs/kafka"
 	_ "github.com/influxdb/telegraf/outputs/mqtt"
 	_ "github.com/influxdb/telegraf/outputs/opentsdb"
+	_ "github.com/influxdb/telegraf/outputs/prometheus"
 )

outputs/prometheus_client/prometheus_client.go

@@ -0,0 +1,102 @@
+package prometheus
+
+import (
+	"fmt"
+	"github.com/influxdb/influxdb/client/v2"
+	"github.com/influxdb/telegraf/outputs"
+	"github.com/prometheus/client_golang/prometheus"
+	"net/http"
+)
+
+type PrometheusClient struct {
+	Listen string
+	server *http.Server
+	gauges map[string]*prometheus.GaugeVec
+}
+
+var sampleConfig = `
+  # Address to listen on
+  listen = ":8000"
+`
+
+func (p *PrometheusClient) Connect() error {
+	if p.Listen == "" {
+		p.Listen = ":8000"
+	}
+	http.Handle("/metrics", prometheus.Handler())
+	server := &http.Server{
+		Addr:    p.Listen,
+		Handler: prometheus.Handler(),
+	}
+	p.server = server
+	p.gauges = make(map[string]*prometheus.GaugeVec)
+	go p.server.ListenAndServe()
+	return nil
+}
+
+func (p *PrometheusClient) Close() error {
+	// TODO: Add a proper close function
+	return nil
+}
+
+func (p *PrometheusClient) SampleConfig() string {
+	return sampleConfig
+}
+
+func (p *PrometheusClient) Description() string {
+	return "Configuration for the Prometheus client to spawn"
+}
+
+func (p *PrometheusClient) Write(points []*client.Point) error {
+	if len(points) == 0 {
+		return nil
+	}
+
+	for _, point := range points {
+		var labels []string
+		name := point.Name()
+		key := name
+
+		for k, _ := range point.Tags() {
+			if len(k) > 0 {
+				labels = append(labels, k)
+				// key += "_" + k
+			}
+		}
+		// sort.Strings(labels)
+
+		if _, ok := p.gauges[key]; !ok {
+			// Setup a new gauge vector
+			p.gauges[key] = prometheus.NewGaugeVec(
+				prometheus.GaugeOpts{
+					Name: key,
+					Help: fmt.Sprintf("Telegraf collected point '%s'", name),
+				},
+				labels,
+			)
+			prometheus.MustRegister(p.gauges[key])
+		}
+
+		l := prometheus.Labels{}
+		for tk, tv := range point.Tags() {
+			l[tk] = tv
+		}
+
+		for _, val := range point.Fields() {
+			switch val.(type) {
+			case int64:
+				ival := val.(int64)
+				p.gauges[key].With(l).Set(float64(ival))
+			case float64:
+				p.gauges[key].With(l).Set(val.(float64))
+			}
+		}
+	}
+	return nil
+}
+
+func init() {
+	outputs.Add("prometheus_client", func() outputs.Output {
+		return &PrometheusClient{}
+	})
+}

plugins/aerospike/aerospike.go

@@ -250,7 +250,8 @@ func get(key []byte, host string) (map[string]string, error) {
 func readAerospikeStats(stats map[string]string, acc plugins.Accumulator, host, namespace string) {
 	for key, value := range stats {
 		tags := map[string]string{
-			"host": host,
+			"host":      host,
+			"namespace": "_service",
 		}
 
 		if namespace != "" {