vendor: bump docker/go-metrics v0.0.1:

full diff: 4ea375f775...v0.0.1

- docker/go-metrics#15 Add functions that instruments http handler using promhttp
- docker/go-metrics#20 Rename LICENSE.code → LICENSE
- docker/go-metrics#22 Support Go Modules

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

vendor/github.com/docker/go-metrics/handler.go

@@ -4,10 +4,71 @@ import (
 	"net/http"
 
 	"github.com/prometheus/client_golang/prometheus"
+	"github.com/prometheus/client_golang/prometheus/promhttp"
+)
+
+// HTTPHandlerOpts describes a set of configurable options of http metrics
+type HTTPHandlerOpts struct {
+	DurationBuckets     []float64
+	RequestSizeBuckets  []float64
+	ResponseSizeBuckets []float64
+}
+
+const (
+	InstrumentHandlerResponseSize = iota
+	InstrumentHandlerRequestSize
+	InstrumentHandlerDuration
+	InstrumentHandlerCounter
+	InstrumentHandlerInFlight
+)
+
+type HTTPMetric struct {
+	prometheus.Collector
+	handlerType int
+}
+
+var (
+	defaultDurationBuckets     = []float64{.005, .01, .025, .05, .1, .25, .5, 1, 2.5, 5, 10, 25, 60}
+	defaultRequestSizeBuckets  = prometheus.ExponentialBuckets(1024, 2, 22) //1K to 4G
+	defaultResponseSizeBuckets = defaultRequestSizeBuckets
 )
 
 // Handler returns the global http.Handler that provides the prometheus
-// metrics format on GET requests
+// metrics format on GET requests. This handler is no longer instrumented.
 func Handler() http.Handler {
-	return prometheus.Handler()
+	return promhttp.Handler()
+}
+
+func InstrumentHandler(metrics []*HTTPMetric, handler http.Handler) http.HandlerFunc {
+	return InstrumentHandlerFunc(metrics, handler.ServeHTTP)
+}
+
+func InstrumentHandlerFunc(metrics []*HTTPMetric, handlerFunc http.HandlerFunc) http.HandlerFunc {
+	var handler http.Handler
+	handler = http.HandlerFunc(handlerFunc)
+	for _, metric := range metrics {
+		switch metric.handlerType {
+		case InstrumentHandlerResponseSize:
+			if collector, ok := metric.Collector.(prometheus.ObserverVec); ok {
+				handler = promhttp.InstrumentHandlerResponseSize(collector, handler)
+			}
+		case InstrumentHandlerRequestSize:
+			if collector, ok := metric.Collector.(prometheus.ObserverVec); ok {
+				handler = promhttp.InstrumentHandlerRequestSize(collector, handler)
+			}
+		case InstrumentHandlerDuration:
+			if collector, ok := metric.Collector.(prometheus.ObserverVec); ok {
+				handler = promhttp.InstrumentHandlerDuration(collector, handler)
+			}
+		case InstrumentHandlerCounter:
+			if collector, ok := metric.Collector.(*prometheus.CounterVec); ok {
+				handler = promhttp.InstrumentHandlerCounter(collector, handler)
+			}
+		case InstrumentHandlerInFlight:
+			if collector, ok := metric.Collector.(prometheus.Gauge); ok {
+				handler = promhttp.InstrumentHandlerInFlight(collector, handler)
+			}
+		}
+	}
+	return handler.ServeHTTP
 }