Move tracer to httptransport

2 files changed, 85 insertions, 2 deletions

diff --git a/internal/httptransport/trace.go b/internal/httptransport/trace.go
new file mode 100644
index 00000000..9ece5fc4
--- /dev/null
+++ b/internal/httptransport/trace.go
@@ -0,0 +1,77 @@
+package httptransport
+
+import (
+	"crypto/tls"
+	"net/http/httptrace"
+	"time"
+
+	"gitlab.com/gitlab-org/labkit/log"
+)
+
+func (mrt *meteredRoundTripper) newTracer(start time.Time) *httptrace.
+	ClientTrace {
+	trace := &httptrace.ClientTrace{
+		GetConn: func(host string) {
+			mrt.httpTraceObserve("httptrace.ClientTrace.GetConn", start)
+
+			log.WithFields(log.Fields{
+				"host": host,
+			}).Traceln("httptrace.ClientTrace.GetConn")
+		},
+		GotConn: func(connInfo httptrace.GotConnInfo) {
+			mrt.httpTraceObserve("httptrace.ClientTrace.GotConn", start)
+
+			log.WithFields(log.Fields{
+				"reused":       connInfo.Reused,
+				"was_idle":     connInfo.WasIdle,
+				"idle_time_ms": connInfo.IdleTime.Milliseconds(),
+			}).Traceln("httptrace.ClientTrace.GotConn")
+		},
+		GotFirstResponseByte: func() {
+			mrt.httpTraceObserve("httptrace.ClientTrace.GotFirstResponseByte", start)
+		},
+		DNSStart: func(d httptrace.DNSStartInfo) {
+			mrt.httpTraceObserve("httptrace.ClientTrace.DNSStart", start)
+		},
+		DNSDone: func(d httptrace.DNSDoneInfo) {
+			mrt.httpTraceObserve("httptrace.ClientTrace.DNSDone", start)
+
+			log.WithFields(log.Fields{}).WithError(d.Err).
+				Traceln("httptrace.ClientTrace.DNSDone")
+		},
+		ConnectStart: func(net, addr string) {
+			mrt.httpTraceObserve("httptrace.ClientTrace.ConnectStart", start)
+
+			log.WithFields(log.Fields{
+				"network": net,
+				"address": addr,
+			}).Traceln("httptrace.ClientTrace.ConnectStart")
+		},
+		ConnectDone: func(net string, addr string, err error) {
+			mrt.httpTraceObserve("httptrace.ClientTrace.ConnectDone", start)
+
+			log.WithFields(log.Fields{
+				"network": net,
+				"address": addr,
+			}).WithError(err).Traceln("httptrace.ClientTrace.ConnectDone")
+		},
+		TLSHandshakeStart: func() {
+			mrt.httpTraceObserve("httptrace.ClientTrace.TLSHandshakeStart", start)
+		},
+		TLSHandshakeDone: func(connState tls.ConnectionState, err error) {
+			mrt.httpTraceObserve("httptrace.ClientTrace.TLSHandshakeDone", start)
+
+			log.WithFields(log.Fields{
+				"version":            connState.Version,
+				"connection_resumed": connState.DidResume,
+			}).WithError(err).Traceln("httptrace.ClientTrace.TLSHandshakeDone")
+		},
+	}
+
+	return trace
+}
+
+func (mrt *meteredRoundTripper) httpTraceObserve(label string, start time.Time) {
+	mrt.tracer.WithLabelValues(label).
+		Observe(time.Since(start).Seconds())
+}
diff --git a/internal/httptransport/transport.go b/internal/httptransport/transport.go
index 304ac1c6..bc871ea7 100644
--- a/internal/httptransport/transport.go
+++ b/internal/httptransport/transport.go
@@ -5,6 +5,7 @@ import (
 	"crypto/x509"
 	"net"
 	"net/http"
+	"net/http/httptrace"
 	"strconv"
 	"strings"
 	"sync"
@@ -27,6 +28,7 @@ var (
 type meteredRoundTripper struct {
 	next      http.RoundTripper
 	name      string
+	tracer    *prometheus.HistogramVec
 	durations *prometheus.HistogramVec
 	counter   *prometheus.CounterVec
 }
@@ -46,11 +48,13 @@ func newInternalTransport() *http.Transport {
 
 // NewTransportWithMetrics will create a custom http.RoundTripper that can be used with an http.Client.
 // The RoundTripper will report metrics based on the collectors passed.
-func NewTransportWithMetrics(name string, histogramVec *prometheus.HistogramVec, counterVec *prometheus.CounterVec) http.RoundTripper {
+func NewTransportWithMetrics(name string, tracerVec, durationsVec *prometheus.
+	HistogramVec, counterVec *prometheus.CounterVec) http.RoundTripper {
 	return &meteredRoundTripper{
 		next:      InternalTransport,
 		name:      name,
-		durations: histogramVec,
+		tracer:    tracerVec,
+		durations: durationsVec,
 		counter:   counterVec,
 	}
 }
@@ -84,6 +88,8 @@ func loadPool() {
 func (mrt *meteredRoundTripper) RoundTrip(r *http.Request) (*http.Response, error) {
 	start := time.Now()
 
+	r = r.WithContext(httptrace.WithClientTrace(r.Context(), mrt.newTracer(start)))
+
 	resp, err := mrt.next.RoundTrip(r)
 	if err != nil {
 		mrt.counter.WithLabelValues("error").Inc()