From bc54582c5ec9f1b8e0383eaa8628db3bca88f041 Mon Sep 17 00:00:00 2001
From: beorn7 <bjoern@rabenste.in>
Date: Thu, 16 May 2019 11:03:34 +0200
Subject: [PATCH] Make use of pre-existing context in
 InstrumentRoundTripperTrace

Fixes #580

Signed-off-by: beorn7 <bjoern@rabenste.in>
---
 prometheus/promhttp/instrument_client.go | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/prometheus/promhttp/instrument_client.go b/prometheus/promhttp/instrument_client.go
index d5172db..83c49b6 100644
--- a/prometheus/promhttp/instrument_client.go
+++ b/prometheus/promhttp/instrument_client.go
@@ -14,7 +14,6 @@
 package promhttp
 
 import (
-	"context"
 	"crypto/tls"
 	"net/http"
 	"net/http/httptrace"
@@ -213,7 +212,7 @@ func InstrumentRoundTripperTrace(it *InstrumentTrace, next http.RoundTripper) Ro
 				}
 			},
 		}
-		r = r.WithContext(httptrace.WithClientTrace(context.Background(), trace))
+		r = r.WithContext(httptrace.WithClientTrace(r.Context(), trace))
 
 		return next.RoundTrip(r)
 	})