initial commit

metrics/main.go

@@ -0,0 +1,46 @@
+package metrics
+
+import (
+	"fmt"
+	"net/http"
+	"strconv"
+	"time"
+
+	"github.com/prometheus/client_golang/prometheus"
+	"github.com/prometheus/client_golang/prometheus/promauto"
+)
+
+var (
+	responseLatency = promauto.NewHistogramVec(prometheus.HistogramOpts{
+		Name: "response_latency",
+		Help: "latency of the response",
+	},
+		// favor adicionar itens à essa lista com cautela.
+		// uma alta cardinalidade em vetores de uma métrica no prometheus
+		// pode causar impactos na performance do servidor remoto.
+		[]string{"status", "method", "path", "panic"},
+	)
+
+	TransactionLatency = promauto.NewHistogramVec(prometheus.HistogramOpts{
+		Name: "transaction_db_latency",
+		Help: "latency of the response",
+	}, []string{})
+)
+
+func ResponseLatencyObserve(latency time.Duration, statusCode int, panicked bool, r *http.Request) {
+	var (
+		method = r.Method
+		path   = r.URL.Path
+	)
+	observer, err := responseLatency.GetMetricWithLabelValues(
+		strconv.Itoa(statusCode),
+		method,
+		path,
+		fmt.Sprint(panicked),
+	)
+	if err != nil {
+		// não temos como tratar esse erro
+		panic(err)
+	}
+	observer.Observe(latency.Seconds())
+}