Add Inner Ring code

pkg/util/profiler/metrics.go

@@ -0,0 +1,32 @@
+package profiler
+
+import (
+	"context"
+
+	"github.com/prometheus/client_golang/prometheus/promhttp"
+	"github.com/spf13/viper"
+	"go.uber.org/zap"
+)
+
+// Metrics is an interface of metric tool.
+type Metrics interface {
+	Start(ctx context.Context)
+	Stop()
+}
+
+const metricsKey = "metrics"
+
+// NewMetrics is a metric tool's constructor.
+func NewMetrics(l *zap.Logger, v *viper.Viper) Metrics {
+	if !v.GetBool(metricsKey + ".enabled") {
+		l.Debug("metrics server disabled")
+		return nil
+	}
+
+	return newHTTPServer(httpParams{
+		Key:     metricsKey,
+		Viper:   v,
+		Logger:  l,
+		Handler: promhttp.Handler(),
+	})
+}