bugfix: preserve optional interfaces on http.ResponseWriter (#91)

* bugfix: preserves optional interfaces on http.ResponseWriter

* add test for preserving optional interfaces

* removes support for go 1.7 and 1.8

.travis.yml

@@ -5,8 +5,6 @@ go_import_path: github.com/aws/aws-xray-sdk-go
 sudo: required
 
 go:
-  - "1.7"
-  - "1.8"
   - "1.9"
   - "1.10"
   - "1.11" 
@@ -25,28 +23,20 @@ env:
 
 before_install:
   - echo $TRAVIS_GO_VERSION
-  - if [ $TRAVIS_GO_VERSION == "1.7" ] ||
-    [ $TRAVIS_GO_VERSION == "1.8" ]; then
-      export DEP_MANAGEMENT_TOOL="GLIDE";
-    elif [ $TRAVIS_GO_VERSION == "1.9" ] ||
+  - if [ $TRAVIS_GO_VERSION == "1.9" ] ||
     [ $TRAVIS_GO_VERSION == "1.10" ]; then
       export DEP_MANAGEMENT_TOOL="DEP";
     else
       export DEP_MANAGEMENT_TOOL="MODULE";
     fi
   - echo $DEP_MANAGEMENT_TOOL
-  - if [ $DEP_MANAGEMENT_TOOL == "GLIDE" ]; then
-      go get -v github.com/Masterminds/glide;
-      cd $GOPATH/src/github.com/Masterminds/glide && git checkout 67790b3dbede72cfdc54aa53be4706322c9499e0 && go install && cd -;
-    elif [ $DEP_MANAGEMENT_TOOL == "DEP" ]; then
+  - if [ $DEP_MANAGEMENT_TOOL == "DEP" ]; then
       curl -L -s https://github.com/golang/dep/releases/download/v${DEP_VERSION}/dep-linux-amd64 -o $GOPATH/bin/dep;
       chmod +x $GOPATH/bin/dep;
     fi
 
 install:
-  - if [ $DEP_MANAGEMENT_TOOL == "GLIDE" ]; then
-      glide install;
-    elif [ $DEP_MANAGEMENT_TOOL == "DEP" ]; then
+  - if [ $DEP_MANAGEMENT_TOOL == "DEP" ]; then
       dep ensure;
     else
       go get;
@@ -57,6 +47,4 @@ script:
 
 matrix:
   allow_failures:
-    - go: tip
-    - go: "1.7"
-    - go: "1.8"
+    - go: tip

README.md

@@ -6,7 +6,7 @@
 
 ## Installing
 
-The AWS X-Ray SDK for Go is compatible with Go 1.7 and above.
+The AWS X-Ray SDK for Go is compatible with Go 1.9 and above.
 
 Install the SDK using the following command (The SDK's non-testing dependencies will be installed):
 Use `go get` to retrieve the SDK to add it to your `GOPATH` workspace, or your project's Go module dependencies (Go 1.11 and up):

xray/handler.go

@@ -158,20 +158,21 @@ func httpTrace(seg *Segment, h http.Handler, w http.ResponseWriter, r *http.Requ
 	w.Header().Set(TraceIDHeaderKey, respHeader.String())
 	seg.Unlock()
 
-	resp := &responseCapturer{w, 200, 0}
+	capturer := &responseCapturer{w, 200, 0}
+	resp := capturer.wrappedResponseWriter()
 	h.ServeHTTP(resp, r)
 
 	seg.Lock()
-	seg.GetHTTP().GetResponse().Status = resp.status
-	seg.GetHTTP().GetResponse().ContentLength, _ = strconv.Atoi(resp.Header().Get("Content-Length"))
+	seg.GetHTTP().GetResponse().Status = capturer.status
+	seg.GetHTTP().GetResponse().ContentLength, _ = strconv.Atoi(capturer.Header().Get("Content-Length"))
 
-	if resp.status >= 400 && resp.status < 500 {
+	if capturer.status >= 400 && capturer.status < 500 {
 		seg.Error = true
 	}
-	if resp.status == 429 {
+	if capturer.status == 429 {
 		seg.Throttle = true
 	}
-	if resp.status >= 500 && resp.status < 600 {
+	if capturer.status >= 500 && capturer.status < 600 {
 		seg.Fault = true
 	}
 	seg.Unlock()
@@ -190,22 +191,6 @@ func clientIP(r *http.Request) (string, bool) {
 	return ip, false
 }
 
-type responseCapturer struct {
-	http.ResponseWriter
-	status int
-	length int
-}
-
-func (w *responseCapturer) WriteHeader(status int) {
-	w.status = status
-	w.ResponseWriter.WriteHeader(status)
-}
-
-func (w *responseCapturer) Write(data []byte) (int, error) {
-	w.length += len(data)
-	return w.ResponseWriter.Write(data)
-}
-
 func btoi(b bool) int {
 	if b {
 		return 1

xray/handler_test.go

@@ -9,15 +9,17 @@
 package xray
 
 import (
+	"io"
 	"net/http"
 	"net/http/httptest"
 	"strings"
 	"testing"
 
 	"context"
-	"github.com/stretchr/testify/assert"
 	"os"
 	"time"
+
+	"github.com/stretchr/testify/assert"
 )
 
 func TestNewFixedSegmentName(t *testing.T) {
@@ -155,3 +157,30 @@ func TestNonRootHandler(t *testing.T) {
 	assert.Equal(t, "reqid", s.ParentID)
 	assert.Equal(t, true, s.Sampled)
 }
+
+func TestXRayHandlerPreservesOptionalInterfaces(t *testing.T) {
+	handler := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		_, isCloseNotifier := w.(http.CloseNotifier)
+		_, isFlusher := w.(http.Flusher)
+		_, isHijacker := w.(http.Hijacker)
+		_, isPusher := w.(http.Pusher)
+		_, isReaderFrom := w.(io.ReaderFrom)
+
+		assert.True(t, isCloseNotifier)
+		assert.True(t, isFlusher)
+		assert.True(t, isHijacker)
+		assert.True(t, isReaderFrom)
+		// Pusher is only available when using http/2, so should not be present
+		assert.False(t, isPusher)
+
+		w.WriteHeader(202)
+	})
+
+	ts := httptest.NewServer(Handler(NewFixedSegmentNamer("test"), handler))
+	defer ts.Close()
+
+	req := httptest.NewRequest("GET", ts.URL, strings.NewReader(""))
+
+	_, err := http.DefaultTransport.RoundTrip(req)
+	assert.NoError(t, err)
+}