Merge pull request #136 from westphahl/match-metric-type

Allow mapping match on metric type

README.md

@@ -251,6 +251,21 @@ mappings:
 You can drop any metric using the normal match syntax.
 The default action is "map" which does the normal metrics mapping.
 
+StatsD allows emitting of different metric types under the same metric name,
+but the Prometheus client library can't merge those. For this use-case the
+mapping definition allows you to specify which metric type to match:
+
+```
+mappings:
+- match: test.foo.*
+  name: "test_foo"
+  match_metric_type: counter
+  labels:
+    provider: "$1"
+```
+
+Possible values for `match_metric_type` are `gauge`, `counter` and `timer`.
+
 ## Using Docker
 
 You can deploy this exporter using the [prom/statsd-exporter](https://registry.hub.docker.com/u/prom/statsd-exporter/) Docker image.

exporter.go

@@ -182,6 +182,7 @@ type Event interface {
 	MetricName() string
 	Value() float64
 	Labels() map[string]string
+	MetricType() metricType
 }
 
 type CounterEvent struct {
@@ -193,6 +194,7 @@ type CounterEvent struct {
 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 }
+func (c *CounterEvent) MetricType() metricType    { return metricTypeCounter }
 
 type GaugeEvent struct {
 	metricName string
@@ -204,6 +206,7 @@ type GaugeEvent struct {
 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 }
+func (c *GaugeEvent) MetricType() metricType    { return metricTypeGauge }
 
 type TimerEvent struct {
 	metricName string
@@ -214,6 +217,7 @@ type TimerEvent struct {
 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 }
+func (c *TimerEvent) MetricType() metricType    { return metricTypeTimer }
 
 type Events []Event
 
@@ -248,7 +252,7 @@ func (b *Exporter) Listen(e <-chan Events) {
 			metricName := ""
 			prometheusLabels := event.Labels()
 
-			mapping, labels, present := b.mapper.getMapping(event.MetricName())
+			mapping, labels, present := b.mapper.getMapping(event.MetricName(), event.MetricType())
 			if mapping == nil {
 				mapping = &metricMapping{}
 			}

mapper.go

@@ -45,16 +45,19 @@ type metricMapper struct {
 	mutex    sync.Mutex
 }
 
+type matchMetricType string
+
 type metricMapping struct {
-	Match     string `yaml:"match"`
-	Name      string `yaml:"name"`
-	regex     *regexp.Regexp
-	Labels    prometheus.Labels `yaml:"labels"`
-	TimerType timerType         `yaml:"timer_type"`
-	Buckets   []float64         `yaml:"buckets"`
-	MatchType matchType         `yaml:"match_type"`
-	HelpText  string            `yaml:"help"`
-	Action    actionType        `yaml:"action"`
+	Match           string `yaml:"match"`
+	Name            string `yaml:"name"`
+	regex           *regexp.Regexp
+	Labels          prometheus.Labels `yaml:"labels"`
+	TimerType       timerType         `yaml:"timer_type"`
+	Buckets         []float64         `yaml:"buckets"`
+	MatchType       matchType         `yaml:"match_type"`
+	HelpText        string            `yaml:"help"`
+	Action          actionType        `yaml:"action"`
+	MatchMetricType metricType        `yaml:"match_metric_type"`
 }
 
 func (m *metricMapper) initFromYAMLString(fileContents string) error {
@@ -148,7 +151,7 @@ func (m *metricMapper) initFromFile(fileName string) error {
 	return m.initFromYAMLString(string(mappingStr))
 }
 
-func (m *metricMapper) getMapping(statsdMetric string) (*metricMapping, prometheus.Labels, bool) {
+func (m *metricMapper) getMapping(statsdMetric string, statsdMetricType metricType) (*metricMapping, prometheus.Labels, bool) {
 	m.mutex.Lock()
 	defer m.mutex.Unlock()
 
@@ -165,6 +168,10 @@ func (m *metricMapper) getMapping(statsdMetric string) (*metricMapping, promethe
 			matches,
 		))
 
+		if mt := mapping.MatchMetricType; mt != "" && mt != statsdMetricType {
+			continue
+		}
+
 		labels := prometheus.Labels{}
 		for label, valueExpr := range mapping.Labels {
 			value := mapping.regex.ExpandString([]byte{}, valueExpr, statsdMetric, matches)

mapper_test.go

@@ -302,6 +302,27 @@ mappings:
 - match: test.*.*
   timer_type: wrong
   name: "foo"
+  labels: {}
+    `,
+			configBad: true,
+		},
+		// Config with good metric type.
+		{
+			config: `---
+mappings:
+- match: test.*.*
+  match_metric_type: counter
+  name: "foo"
+  labels: {}
+    `,
+		},
+		// Config with bad metric type matcher.
+		{
+			config: `---
+mappings:
+- match: test.*.*
+  match_metric_type: wrong
+  name: "foo"
   labels: {}
     `,
 			configBad: true,
@@ -432,8 +453,9 @@ mappings:
 			t.Fatalf("%d. Expected bad config, but loaded ok: %s", i, scenario.config)
 		}
 
+		var dummyMetricType metricType = ""
 		for metric, mapping := range scenario.mappings {
-			m, labels, present := mapper.getMapping(metric)
+			m, labels, present := mapper.getMapping(metric, dummyMetricType)
 			if present && mapping.name != "" && m.Name != mapping.name {
 				t.Fatalf("%d.%q: Expected name %v, got %v", i, metric, m.Name, mapping.name)
 			}

metric_type.go

@@ -0,0 +1,43 @@
+// Copyright 2018 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package main
+
+import "fmt"
+
+type metricType string
+
+const (
+	metricTypeCounter metricType = "counter"
+	metricTypeGauge   metricType = "gauge"
+	metricTypeTimer   metricType = "timer"
+)
+
+func (m *metricType) UnmarshalYAML(unmarshal func(interface{}) error) error {
+	var v string
+	if err := unmarshal(&v); err != nil {
+		return err
+	}
+
+	switch metricType(v) {
+	case metricTypeCounter:
+		*m = metricTypeCounter
+	case metricTypeGauge:
+		*m = metricTypeGauge
+	case metricTypeTimer:
+		*m = metricTypeTimer
+	default:
+		return fmt.Errorf("invalid metric type '%s'", v)
+	}
+	return nil
+}