Inject the mappings count metric into the library package

so that it can be initialized with an exporter-specific name.

Signed-off-by: Matthias Rampke <mr@soundcloud.com>

main.go

@@ -188,7 +188,7 @@ func main() {
 		go tl.Listen(events)
 	}
 
-	mapper := &mapper.MetricMapper{}
+	mapper := &mapper.MetricMapper{MappingsCount: mappingsCount}
 	if *mappingConfig != "" {
 		err := mapper.InitFromFile(*mappingConfig)
 		if err != nil {

pkg/mapper/mapper.go

@@ -44,6 +44,8 @@ type MetricMapper struct {
 	Defaults mapperConfigDefaults `yaml:"defaults"`
 	Mappings []MetricMapping      `yaml:"mappings"`
 	mutex    sync.Mutex
+
+	MappingsCount prometheus.Gauge
 }
 
 type matchMetricType string
@@ -159,7 +161,9 @@ func (m *MetricMapper) InitFromYAMLString(fileContents string) error {
 	m.Defaults = n.Defaults
 	m.Mappings = n.Mappings
 
-	mappingsCount.Set(float64(len(n.Mappings)))
+	if m.MappingsCount != nil {
+		m.MappingsCount.Set(float64(len(n.Mappings)))
+	}
 
 	return nil
 }

pkg/mapper/telemetry.go

@@ -1,29 +0,0 @@
-// Copyright 2013 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 mapper
-
-import (
-	"github.com/prometheus/client_golang/prometheus"
-)
-
-var (
-	mappingsCount = prometheus.NewGauge(prometheus.GaugeOpts{
-		Name: "statsd_exporter_loaded_mappings",
-		Help: "The current number of configured metric mappings.",
-	})
-)
-
-func init() {
-	prometheus.MustRegister(mappingsCount)
-}

telemetry.go

@@ -91,6 +91,10 @@ var (
 		},
 		[]string{"outcome"},
 	)
+	mappingsCount = prometheus.NewGauge(prometheus.GaugeOpts{
+		Name: "statsd_exporter_loaded_mappings",
+		Help: "The current number of configured metric mappings.",
+	})
 	conflictingEventStats = prometheus.NewCounterVec(
 		prometheus.CounterOpts{
 			Name: "statsd_exporter_events_conflict_total",
@@ -112,5 +116,6 @@ func init() {
 	prometheus.MustRegister(tagsReceived)
 	prometheus.MustRegister(tagErrors)
 	prometheus.MustRegister(configLoads)
+	prometheus.MustRegister(mappingsCount)
 	prometheus.MustRegister(conflictingEventStats)
 }