Extract metrics to own package and refactor implementations

metrics/prometheus.go

@@ -0,0 +1,45 @@
+package metrics
+
+import (
+	"github.com/containous/traefik/types"
+	"github.com/go-kit/kit/metrics/prometheus"
+	stdprometheus "github.com/prometheus/client_golang/prometheus"
+)
+
+const (
+	metricNamePrefix = "traefik_"
+
+	reqsTotalName    = metricNamePrefix + "requests_total"
+	reqDurationName  = metricNamePrefix + "request_duration_seconds"
+	retriesTotalName = metricNamePrefix + "backend_retries_total"
+)
+
+// RegisterPrometheus registers all Prometheus metrics.
+// It must be called only once and failing to register the metrics will lead to a panic.
+func RegisterPrometheus(config *types.Prometheus) Registry {
+	buckets := []float64{0.1, 0.3, 1.2, 5.0}
+	if config.Buckets != nil {
+		buckets = config.Buckets
+	}
+
+	reqCounter := prometheus.NewCounterFrom(stdprometheus.CounterOpts{
+		Name: reqsTotalName,
+		Help: "How many HTTP requests processed, partitioned by status code and method.",
+	}, []string{"service", "code", "method"})
+	reqDurationHistogram := prometheus.NewHistogramFrom(stdprometheus.HistogramOpts{
+		Name:    reqDurationName,
+		Help:    "How long it took to process the request.",
+		Buckets: buckets,
+	}, []string{"service", "code"})
+	retryCounter := prometheus.NewCounterFrom(stdprometheus.CounterOpts{
+		Name: retriesTotalName,
+		Help: "How many request retries happened in total.",
+	}, []string{"service"})
+
+	return &standardRegistry{
+		enabled:              true,
+		reqsCounter:          reqCounter,
+		reqDurationHistogram: reqDurationHistogram,
+		retriesCounter:       retryCounter,
+	}
+}