ref: add metrics prometheus exporter

pkg/otelify/otelify.go

@@ -4,8 +4,6 @@ import (
 	"context"
 	"log"
 
-	"github.com/prometheus/client_golang/prometheus"
-	"github.com/prometheus/client_golang/prometheus/promauto"
 	"google.golang.org/grpc"
 
 	"go.opentelemetry.io/otel"
@@ -17,13 +15,6 @@ import (
 	semconv "go.opentelemetry.io/otel/semconv/v1.7.0"
 )
 
-var MetricRequestLatencyProxy = promauto.NewHistogram(prometheus.HistogramOpts{
-	Namespace: "ngonx",
-	Name:      "request_latency_seconds",
-	Help:      "Request Latency",
-	Buckets:   prometheus.ExponentialBuckets(.0001, 2, 50),
-})
-
 // Initializes an OTLP exporter, and configures the corresponding trace and
 // metric providers.
 func InitProvider(name, version, namEnv, endpoint string) func() {

pkg/otelify/prometheus.go

@@ -0,0 +1,24 @@
+package otelify
+
+import (
+	"fmt"
+	"log"
+	"net/http"
+
+	"github.com/prometheus/client_golang/prometheus"
+	"github.com/prometheus/client_golang/prometheus/promauto"
+	"github.com/prometheus/client_golang/prometheus/promhttp"
+)
+
+var MetricRequestLatencyProxy = promauto.NewHistogram(prometheus.HistogramOpts{
+	Namespace: "ngonx",
+	Name:      "request_latency_seconds",
+	Help:      "Request Latency",
+	Buckets:   prometheus.ExponentialBuckets(.0001, 2, 50),
+})
+
+func ExposeMetricServer(configPort int) {
+	http.Handle("/metrics", promhttp.Handler())
+	port := fmt.Sprintf(":%d", configPort)
+	log.Fatal(http.ListenAndServe(port, nil))
+}