content: add introducing http tracing post

Updates golang/go#17152.

Change-Id: I08d4174ba62f6dc4028bd17a911b92fc373b81e4
Reviewed-on: https://go-review.googlesource.com/29685
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Andrew Gerrand <adg@golang.org>

1 files changed, 28 insertions, 0 deletions

diff --git a/content/http-tracing/trace.go b/content/http-tracing/trace.go
new file mode 100644
index 0000000..2d6d75e
--- /dev/null
+++ b/content/http-tracing/trace.go
@@ -0,0 +1,28 @@
+// +build OMIT
+
+package main
+
+import (
+	"fmt"
+	"log"
+	"net/http"
+	"net/http/httptrace"
+)
+
+func trace() {
+	// START OMIT
+	req, _ := http.NewRequest("GET", "http://example.com", nil)
+	trace := &httptrace.ClientTrace{
+		DNSDone: func(dnsInfo httptrace.DNSDoneInfo) {
+			fmt.Printf("DNS Info: %+v\n", dnsInfo)
+		},
+		GotConn: func(connInfo httptrace.GotConnInfo) {
+			fmt.Printf("Got Conn: %+v\n", connInfo)
+		},
+	}
+	req = req.WithContext(httptrace.WithClientTrace(req.Context(), trace))
+	if _, err := http.DefaultTransport.RoundTrip(req); err != nil {
+		log.Fatal(err)
+	}
+	// STOP OMIT
+}