feat: Add configuration option to enable/disable profiling metrics

Added a new configuration `enable_profiling_metrics` which
enable/disable the default runtime metrics exported by the Prometheus
client package.

BREAKING CHANGE: Changed default behavior to exclude runtime metrics.
        Enable with enable_profiling_metrics configuration option.
Signed-off-by: Alf-Rune Siqveland <alf.rune@siqveland.no>

cmd/mqtt2prometheus.go

@@ -151,9 +151,16 @@ func main() {
 		time.Sleep(10 * time.Second)
 	}
 
-	prometheus.MustRegister(ingest.Collector())
-	prometheus.MustRegister(collector)
-	http.Handle("/metrics", promhttp.Handler())
+	var gatherer prometheus.Gatherer
+	if cfg.EnableProfiling {
+		gatherer = prometheus.DefaultGatherer
+	} else {
+		reg := prometheus.NewRegistry()
+		reg.MustRegister(ingest.Collector())
+		reg.MustRegister(collector)
+		gatherer = reg
+	}
+	http.Handle("/metrics", promhttp.HandlerFor(gatherer, promhttp.HandlerOpts{}))
 	s := &http.Server{
 		Addr:    getListenAddress(),
 		Handler: http.DefaultServeMux,

config.yaml.dist

@@ -19,6 +19,10 @@ mqtt:
   # device_id_regex: "(.*/)?(?P<deviceid>.*)"
   # The MQTT QoS level
   qos: 0
+# Export internal profiling metrics including CPU, Memory, uptime, open file
+# descriptors, as well as metrics exported by Go runtime such as information about
+# heap and garbage collection stats.
+enable_profiling_metrics: false
 cache:
   # Timeout. Each received metric will be presented for this time if no update is send via MQTT.
   # Set the timeout to -1 to disable the deletion of metrics from the cache. The exporter presents the ingest timestamp

pkg/config/config.go

@@ -89,10 +89,11 @@ func MustNewRegexp(pattern string) *Regexp {
 }
 
 type Config struct {
-	JsonParsing *JsonParsingConfig `yaml:"json_parsing,omitempty"`
-	Metrics     []MetricConfig     `yaml:"metrics"`
-	MQTT        *MQTTConfig        `yaml:"mqtt,omitempty"`
-	Cache       *CacheConfig       `yaml:"cache,omitempty"`
+	JsonParsing     *JsonParsingConfig `yaml:"json_parsing,omitempty"`
+	Metrics         []MetricConfig     `yaml:"metrics"`
+	MQTT            *MQTTConfig        `yaml:"mqtt,omitempty"`
+	Cache           *CacheConfig       `yaml:"cache,omitempty"`
+	EnableProfiling bool               `yaml:"enable_profiling_metrics,omitempty"`
 }
 
 type CacheConfig struct {