[Prometheus] Add new prometheus metrics and metrics endpoint

metrics/prometheus/metrics.go

@@ -1,37 +1,42 @@
 package prometheus
 
-import "github.com/prometheus/client_golang/prometheus"
-
-type Metrics struct {
-	Counter      *prometheus.CounterVec
-	ResponseTime *prometheus.HistogramVec
-}
+// Metrics prototypes
+// Example:
+// 	Counter      *prometheus.CounterVec
+// 	ResponseTime *prometheus.HistogramVec
+type Metrics struct{}
 
+// Method for creation new custom Prometheus  metrics
+// Example:
+// 	pm := &Metrics{
+//		Counter: prometheus.NewCounterVec(
+//			prometheus.CounterOpts{
+//				Name:        "servicename_requests_total",
+//				Help:        "Description",
+//				ConstLabels: map[string]string{
+//					"version":   version,
+//					"hash":      hash,
+//					"buildTime": buildTime,
+//				},
+//			},
+//			[]string{"endpoint"},
+//		),
+//		ResponseTime: prometheus.NewHistogramVec(
+//			prometheus.HistogramOpts{
+//				Name:        "servicename_response_time_seconds",
+//				Help:        "Description",
+//				ConstLabels: map[string]string{
+//					"version":   version,
+//					"hash":      hash,
+//					"buildTime": buildTime,
+//				},
+//			},
+//			[]string{"endpoint"},
+//		),
+//	}
+//	prometheus.Register(pm.Counter)
+//  prometheus.Register(pm.ResponseTime)
 func NewMetrics(version, hash, buildTime string) *Metrics {
-	labels := map[string]string{
-		"version":   version,
-		"hash":      hash,
-		"buildTime": buildTime,
-	}
-	pm := &Metrics{
-		Counter: prometheus.NewCounterVec(
-			prometheus.CounterOpts{
-				Name:        "sts_requests_total",
-				Help:        "Secure token service requests served per endpoint",
-				ConstLabels: labels,
-			},
-			[]string{"endpoint"},
-		),
-		ResponseTime: prometheus.NewHistogramVec(
-			prometheus.HistogramOpts{
-				Name:        "sts_response_time_seconds",
-				Help:        "Secure token service response time served per endpoint",
-				ConstLabels: labels,
-			},
-			[]string{"endpoint"},
-		),
-	}
-	prometheus.Register(pm.Counter)
-	prometheus.Register(pm.ResponseTime)
+	pm := &Metrics{}
 	return pm
 }

metrics/prometheus/middleware.go

@@ -2,7 +2,6 @@ package prometheus
 
 import (
 	"net/http"
-	"time"
 )
 
 type MetricsManager struct {
@@ -15,9 +14,14 @@ func NewMetricsManager(version, hash, buildTime string) *MetricsManager {
 	}
 }
 
+// Main middleware method to collect metrics for Prometheus.
+// Example:
+//	start := time.Now()
+//	next(rw, r)
+//	Request counter metric
+//	pmm.prometheusMetrics.Counter.WithLabelValues(r.URL.Path).Inc()
+//	Response time metric
+//	pmm.prometheusMetrics.ResponseTime.WithLabelValues(r.URL.Path).Observe(time.Since(start).Seconds())
 func (pmm *MetricsManager) ServeHTTP(rw http.ResponseWriter, r *http.Request, next http.HandlerFunc) {
-	start := time.Now()
 	next(rw, r)
-	pmm.prometheusMetrics.Counter.WithLabelValues(r.URL.Path).Inc()
-	pmm.prometheusMetrics.ResponseTime.WithLabelValues(r.URL.Path).Observe(time.Since(start).Seconds())
 }