net/http/httputil: make ReverseProxy return 502 Bad Gateway instead of 500

... when the backend can't be reached.

Fixes #9864

Change-Id: I9e4814824943060e0101b6236d6dfd8d7822b4c7
Reviewed-on: https://go-review.googlesource.com/21363
Reviewed-by: Andrew Gerrand <adg@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

diff --git a/src/net/http/httputil/reverseproxy.go b/src/net/http/httputil/reverseproxy.go
index ecee0f242a98fad5e5a6128b33bcad23c2612ac7..44d15ff6be7f086fdf98fe35fad4f51bc3716428 100644 (file)
--- a/src/net/http/httputil/reverseproxy.go
+++ b/src/net/http/httputil/reverseproxy.go
@@ -210,7 +210,7 @@ func (p *ReverseProxy) ServeHTTP(rw http.ResponseWriter, req *http.Request) {
        res, err := transport.RoundTrip(outreq)
        if err != nil {
                p.logf("http: proxy error: %v", err)
-               rw.WriteHeader(http.StatusInternalServerError)
+               rw.WriteHeader(http.StatusBadGateway)
                return
        }
 

diff --git a/src/net/http/httputil/reverseproxy_test.go b/src/net/http/httputil/reverseproxy_test.go
index 0849427b85cce40f6e7a262d0db2806c2bb8f209..e9c0658271f06cdf68c754bb7c4e19b2c23f4d40 100644 (file)
--- a/src/net/http/httputil/reverseproxy_test.go
+++ b/src/net/http/httputil/reverseproxy_test.go
@@ -33,6 +33,11 @@ func TestReverseProxy(t *testing.T) {
        const backendResponse = "I am the backend"
        const backendStatus = 404
        backend := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+               if r.Method == "GET" && r.FormValue("mode") == "hangup" {
+                       c, _, _ := w.(http.Hijacker).Hijack()
+                       c.Close()
+                       return
+               }
                if len(r.TransferEncoding) > 0 {
                        t.Errorf("backend got unexpected TransferEncoding: %v", r.TransferEncoding)
                }
@@ -69,6 +74,7 @@ func TestReverseProxy(t *testing.T) {
                t.Fatal(err)
        }
        proxyHandler := NewSingleHostReverseProxy(backendURL)
+       proxyHandler.ErrorLog = log.New(ioutil.Discard, "", 0) // quiet for tests
        frontend := httptest.NewServer(proxyHandler)
        defer frontend.Close()
 
@@ -113,6 +119,20 @@ func TestReverseProxy(t *testing.T) {
        if g, e := res.Trailer.Get("X-Trailer"), "trailer_value"; g != e {
                t.Errorf("Trailer(X-Trailer) = %q ; want %q", g, e)
        }
+
+       // Test that a backend failing to be reached or one which doesn't return
+       // a response results in a StatusBadGateway.
+       getReq, _ = http.NewRequest("GET", frontend.URL+"/?mode=hangup", nil)
+       getReq.Close = true
+       res, err = http.DefaultClient.Do(getReq)
+       if err != nil {
+               t.Fatal(err)
+       }
+       res.Body.Close()
+       if res.StatusCode != http.StatusBadGateway {
+               t.Errorf("request to bad proxy = %v; want 502 StatusBadGateway", res.Status)
+       }
+
 }
 
 func TestXForwardedFor(t *testing.T) {