Support datadog extensions to statsd datagrams

Datadog's format extensions allow attaching labels and tags to statsd
metrics, and are documented at
http://docs.datadoghq.com/guides/dogstatsd/#datagram-format

Additionally changes compare method in tests to reflect.DeepEqual, as
the tag maps don't sort deterministically, corrects an inversion in
displaying test failure cases, and treats an invalid sample value as 1
instead of throwing out the sample.

bridge_test.go

@@ -14,7 +14,7 @@
 package main
 
 import (
-	"fmt"
+	"reflect"
 	"testing"
 )
 
@@ -33,6 +33,7 @@ func TestHandlePacket(t *testing.T) {
 				&CounterEvent{
 					metricName: "foo",
 					value:      2,
+					labels:     map[string]string{},
 				},
 			},
 		}, {
@@ -42,6 +43,7 @@ func TestHandlePacket(t *testing.T) {
 				&GaugeEvent{
 					metricName: "foo",
 					value:      3,
+					labels:     map[string]string{},
 				},
 			},
 		}, {
@@ -51,6 +53,27 @@ func TestHandlePacket(t *testing.T) {
 				&TimerEvent{
 					metricName: "foo",
 					value:      200,
+					labels:     map[string]string{},
+				},
+			},
+		}, {
+			name: "datadog tag extension",
+			in:   "foo:100|c|#tag1:bar,tag2:baz,tag3,tag4",
+			out: Events{
+				&CounterEvent{
+					metricName: "foo",
+					value:      100,
+					labels:     map[string]string{"tag1": "bar", "tag2": "baz", "tag3": ".", "tag4": "."},
+				},
+			},
+		}, {
+			name: "datadog tag extension with sampling",
+			in:   "foo:100|c|@0.1|#tag1:bar,tag2,tag3:baz",
+			out: Events{
+				&CounterEvent{
+					metricName: "foo",
+					value:      1000,
+					labels:     map[string]string{"tag1": "bar", "tag2": ".", "tag3": "baz"},
 				},
 			},
 		}, {
@@ -60,26 +83,32 @@ func TestHandlePacket(t *testing.T) {
 				&TimerEvent{
 					metricName: "foo",
 					value:      200,
+					labels:     map[string]string{},
 				},
 				&TimerEvent{
 					metricName: "foo",
 					value:      300,
+					labels:     map[string]string{},
 				},
 				&CounterEvent{
 					metricName: "foo",
 					value:      50,
+					labels:     map[string]string{},
 				},
 				&GaugeEvent{
 					metricName: "foo",
 					value:      6,
+					labels:     map[string]string{},
 				},
 				&CounterEvent{
 					metricName: "bar",
 					value:      1,
+					labels:     map[string]string{},
 				},
 				&TimerEvent{
 					metricName: "bar",
 					value:      5,
+					labels:     map[string]string{},
 				},
 			},
 		}, {
@@ -94,6 +123,13 @@ func TestHandlePacket(t *testing.T) {
 		}, {
 			name: "illegal sampling factor",
 			in:   "foo:1|c|@bar",
+			out: Events{
+				&CounterEvent{
+					metricName: "foo",
+					value:      1,
+					labels:     map[string]string{},
+				},
+			},
 		}, {
 			name: "zero sampling factor",
 			in:   "foo:2|c|@0",
@@ -101,6 +137,7 @@ func TestHandlePacket(t *testing.T) {
 				&CounterEvent{
 					metricName: "foo",
 					value:      2,
+					labels:     map[string]string{},
 				},
 			},
 		}, {
@@ -121,12 +158,12 @@ func TestHandlePacket(t *testing.T) {
 		}
 
 		if len(actual) != len(scenario.out) {
-			t.Fatalf("%d. Expected %d events, got %d", i, len(scenario.out), len(actual))
+			t.Fatalf("%d. Expected %d events, got %d in scenario '%s'", i, len(scenario.out), len(actual), scenario.name)
 		}
 
 		for j, expected := range scenario.out {
-			if fmt.Sprintf("%v", actual[j]) != fmt.Sprintf("%v", expected) {
+			if !reflect.DeepEqual(&expected, &actual[j]) {
-				t.Fatalf("%d.%d. Expected %v, got %v", i, j, actual[j], expected)
+				t.Fatalf("%d.%d. Expected %#v, got %#v in scenario '%s'", i, j, expected, actual[j], scenario.name)
 			}
 		}
 	}

exporter.go

@@ -143,31 +143,38 @@ func (c *SummaryContainer) Get(metricName string, labels prometheus.Labels) prom
 type Event interface {
 	MetricName() string
 	Value() float64
+	Labels() map[string]string
 }
 
 type CounterEvent struct {
 	metricName string
 	value      float64
+	labels     map[string]string
 }
 
 func (c *CounterEvent) MetricName() string        { return c.metricName }
 func (c *CounterEvent) Value() float64            { return c.value }
+func (c *CounterEvent) Labels() map[string]string { return c.labels }
 
 type GaugeEvent struct {
 	metricName string
 	value      float64
+	labels     map[string]string
 }
 
 func (g *GaugeEvent) MetricName() string        { return g.metricName }
 func (g *GaugeEvent) Value() float64            { return g.value }
+func (c *GaugeEvent) Labels() map[string]string { return c.labels }
 
 type TimerEvent struct {
 	metricName string
 	value      float64
+	labels     map[string]string
 }
 
 func (t *TimerEvent) MetricName() string        { return t.metricName }
 func (t *TimerEvent) Value() float64            { return t.value }
+func (c *TimerEvent) Labels() map[string]string { return c.labels }
 
 type Events []Event
 
@@ -194,7 +201,7 @@ func (b *Exporter) Listen(e <-chan Events) {
 		events := <-e
 		for _, event := range events {
 			metricName := ""
-			prometheusLabels := prometheus.Labels{}
+			prometheusLabels := event.Labels()
 
 			labels, present := b.mapper.getMapping(event.MetricName())
 			if present {
@@ -257,22 +264,25 @@ type StatsDListener struct {
 	conn *net.UDPConn
 }
 
-func buildEvent(statType, metric string, value float64) (Event, error) {
+func buildEvent(statType, metric string, value float64, labels map[string]string) (Event, error) {
 	switch statType {
 	case "c":
 		return &CounterEvent{
 			metricName: metric,
 			value:      float64(value),
+			labels:     labels,
 		}, nil
 	case "g":
 		return &GaugeEvent{
 			metricName: metric,
 			value:      float64(value),
+			labels:     labels,
 		}, nil
-	case "ms":
+	case "ms", "h":
 		return &TimerEvent{
 			metricName: metric,
 			value:      float64(value),
+			labels:     labels,
 		}, nil
 	case "s":
 		return nil, fmt.Errorf("No support for StatsD sets")
@@ -301,23 +311,30 @@ func (l *StatsDListener) handlePacket(packet []byte, e chan<- Events) {
 			continue
 		}
 
-		elements := strings.Split(line, ":")
+		elements := strings.SplitN(line, ":", 2)
 		if len(elements) < 2 {
 			networkStats.WithLabelValues("malformed_line").Inc()
 			log.Println("Bad line from StatsD:", line)
 			continue
 		}
 		metric := elements[0]
-		samples := elements[1:]
+		var samples []string
+		if strings.Contains(elements[1], "|#") {
+			// using datadog extensions, disable multi-metrics
+			samples = elements[1:]
+		} else {
+			samples = strings.Split(elements[1], ":")
+		}
 		for _, sample := range samples {
 			components := strings.Split(sample, "|")
 			samplingFactor := 1.0
-			if len(components) < 2 || len(components) > 3 {
+			if len(components) < 2 || len(components) > 4 {
 				networkStats.WithLabelValues("malformed_component").Inc()
 				log.Println("Bad component on line:", line)
 				continue
 			}
 			valueStr, statType := components[0], components[1]
+			labels := map[string]string{}
 			value, err := strconv.ParseFloat(valueStr, 64)
 			if err != nil {
 				log.Printf("Bad value %s on line: %s", valueStr, line)
@@ -325,32 +342,45 @@ func (l *StatsDListener) handlePacket(packet []byte, e chan<- Events) {
 				continue
 			}
 
-			if len(components) == 3 {
+			if len(components) >= 3 {
+				for _, component := range components[2:] {
+					switch component[0] {
+					case '@':
 						if statType != "c" {
 							log.Println("Illegal sampling factor for non-counter metric on line", line)
 							networkStats.WithLabelValues("illegal_sample_factor").Inc()
 						}
-				samplingStr := components[2]
+						samplingFactor, err = strconv.ParseFloat(component[1:], 64)
-				if samplingStr[0] != '@' {
-					log.Printf("Invalid sampling factor %s on line %s", samplingStr, line)
-					networkStats.WithLabelValues("invalid_sample_factor").Inc()
-					continue
-				}
-				samplingFactor, err = strconv.ParseFloat(samplingStr[1:], 64)
 						if err != nil {
-					log.Printf("Invalid sampling factor %s on line %s", samplingStr, line)
+							log.Printf("Invalid sampling factor %s on line %s", component[1:], line)
 							networkStats.WithLabelValues("invalid_sample_factor").Inc()
-					continue
 						}
 						if samplingFactor == 0 {
-					// This should never happen, but avoid division by zero if it does.
-					log.Printf("Invalid zero sampling factor %s on line %s, setting to 1", samplingStr, line)
 							samplingFactor = 1
 						}
 						value /= samplingFactor
+					case '#':
+						networkStats.WithLabelValues("dogstasd_tags").Inc()
+						tags := strings.Split(component[1:], ",")
+						for _, t := range tags {
+							kv := strings.Split(t, ":")
+							if len(kv) == 2 {
+								if len(kv[1]) > 0 {
+									labels[kv[0]] = kv[1]
+								}
+							} else if len(kv) == 1 {
+								labels[kv[0]] = "."
+							}
+						}
+					default:
+						log.Printf("Invalid sampling factor or tag section %s on line %s", components[2], line)
+						networkStats.WithLabelValues("invalid_sample_factor").Inc()
+						continue
+					}
+				}
 			}
 
-			event, err := buildEvent(statType, metric, value)
+			event, err := buildEvent(statType, metric, value, labels)
 			if err != nil {
 				log.Printf("Error building event on line %s: %s", line, err)
 				networkStats.WithLabelValues("illegal_event").Inc()