add http metrics (#205)

metrics/http_metrics.go

@@ -0,0 +1,106 @@
+package metrics
+
+import (
+	"github.com/prometheus/client_golang/prometheus"
+	"time"
+)
+
+const (
+	requestStartedKey         = "request_started"
+	requestDurationSecondsKey = "request_duration_seconds"
+	requestSucceededTotalKey  = "request_succeeded_total"
+	requestClientErrTotalKey  = "request_client_error_total"
+	requestServerErrTotalKey  = "request_server_error_total"
+)
+
+type HttpServerMetric interface {
+	Start(labelValues ...string) time.Time
+	Duration(start time.Time, labelValues ...string)
+	Success(labelValues ...string)
+	ServerError(labelValues ...string)
+	ClientError(labelValues ...string)
+}
+
+type httpServerMetric struct {
+	requestStarted         *prometheus.GaugeVec
+	requestDurationSeconds *prometheus.HistogramVec
+	requestSucceededTotal  *prometheus.CounterVec
+	requestClientErrTotal  *prometheus.CounterVec
+	requestServerErrTotal  *prometheus.CounterVec
+}
+
+func NewHttpServerMetric(
+	namespace string,
+	labelNames []string,
+	staticLabels prometheus.Labels,
+	reg prometheus.Registerer,
+) HttpServerMetric {
+	requestStarted := prometheus.NewGaugeVec(prometheus.GaugeOpts{
+		Namespace: namespace,
+		Name:      requestStartedKey,
+		Help:      "Last Unix time when request started.",
+	}, labelNames)
+
+	requestDurationSeconds := prometheus.NewHistogramVec(prometheus.HistogramOpts{
+		Namespace: namespace,
+		Name:      requestDurationSecondsKey,
+		Help:      "Duration of the executions.",
+	}, labelNames)
+
+	requestSucceededTotal := prometheus.NewCounterVec(prometheus.CounterOpts{
+		Namespace: namespace,
+		Name:      requestSucceededTotalKey,
+		Help:      "Total number of the 2xx requests which succeeded.",
+	}, labelNames)
+
+	requestClientErrTotal := prometheus.NewCounterVec(prometheus.CounterOpts{
+		Namespace: namespace,
+		Name:      requestClientErrTotalKey,
+		Help:      "Total number of the 4xx requests.",
+	}, labelNames)
+
+	requestServerErrTotal := prometheus.NewCounterVec(prometheus.CounterOpts{
+		Namespace: namespace,
+		Name:      requestServerErrTotalKey,
+		Help:      "Total number of the 5xx requests.",
+	}, labelNames)
+
+	Register(staticLabels, reg, requestStarted, requestDurationSeconds, requestSucceededTotal, requestClientErrTotal, requestServerErrTotal)
+
+	return &httpServerMetric{
+		requestStarted:         requestStarted,
+		requestDurationSeconds: requestDurationSeconds,
+		requestSucceededTotal:  requestSucceededTotal,
+		requestClientErrTotal:  requestClientErrTotal,
+		requestServerErrTotal:  requestServerErrTotal,
+	}
+}
+
+func (m *httpServerMetric) Start(labelValues ...string) time.Time {
+	start := time.Now()
+	m.requestStarted.WithLabelValues(labelValues...).SetToCurrentTime()
+	return start
+}
+
+func (m *httpServerMetric) Duration(start time.Time, labelValues ...string) {
+	duration := time.Since(start)
+	m.requestDurationSeconds.WithLabelValues(labelValues...).Observe(duration.Seconds())
+}
+
+func (m *httpServerMetric) Success(labelValues ...string) {
+	m.requestSucceededTotal.WithLabelValues(labelValues...).Inc()
+	m.requestServerErrTotal.WithLabelValues(labelValues...).Add(0)
+	m.requestClientErrTotal.WithLabelValues(labelValues...).Add(0)
+}
+
+func (m *httpServerMetric) ServerError(labelValues ...string) {
+	m.requestSucceededTotal.WithLabelValues(labelValues...).Add(0)
+	m.requestServerErrTotal.WithLabelValues(labelValues...).Inc()
+	m.requestClientErrTotal.WithLabelValues(labelValues...).Add(0)
+}
+
+func (m *httpServerMetric) ClientError(labelValues ...string) {
+	m.requestSucceededTotal.WithLabelValues(labelValues...).Add(0)
+	m.requestServerErrTotal.WithLabelValues(labelValues...).Add(0)
+	m.requestClientErrTotal.WithLabelValues(labelValues...).Inc()
+}

middleware/metrics.go

@@ -11,7 +11,7 @@ const labelPath = "path"
 const labelMethod = "method"
 
 func MetricsMiddleware(namespace string, labels prometheus.Labels, reg prometheus.Registerer) gin.HandlerFunc {
-	perfMetric := metrics.NewPerformanceMetric(namespace, []string{labelPath, labelMethod}, labels, reg)
+	perfMetric := metrics.NewHttpServerMetric(namespace, []string{labelPath, labelMethod}, labels, reg)
 	return func(c *gin.Context) {
 		path := c.FullPath()
 		method := c.Request.Method
@@ -29,14 +29,13 @@ func MetricsMiddleware(namespace string, labels prometheus.Labels, reg prometheu
 		perfMetric.Duration(startTime, labelValues...)
 
 		statusCode := c.Writer.Status()
-		if successfulHttpStatusCode(statusCode) {
+		switch {
+		case 200 <= statusCode && statusCode <= 299:
 			perfMetric.Success(labelValues...)
-		} else {
-			perfMetric.Failure(labelValues...)
+		case 500 <= statusCode && statusCode <= 599:
+			perfMetric.ServerError(labelValues...)
+		case 400 <= statusCode && statusCode <= 499:
+			perfMetric.ClientError(labelValues...)
 		}
 	}
 }
-
-func successfulHttpStatusCode(statusCode int) bool {
-	return 200 <= statusCode && statusCode < 300
-}