fix headers

Signed-off-by: Victor Vieux <vieux@docker.com>

api/api.go

@@ -51,6 +51,7 @@ func getInfo(c *context, w http.ResponseWriter, r *http.Request) {
 		c.debug,
 	}
 
+	w.Header().Set("Content-Type", "application/json")
 	json.NewEncoder(w).Encode(info)
 }
 
@@ -72,6 +73,7 @@ func getVersion(c *context, w http.ResponseWriter, r *http.Request) {
 		Arch:       runtime.GOARCH,
 	}
 
+	w.Header().Set("Content-Type", "application/json")
 	json.NewEncoder(w).Encode(version)
 }
 
@@ -112,6 +114,8 @@ func getContainersJSON(c *context, w http.ResponseWriter, r *http.Request) {
 	}
 
 	sort.Sort(sort.Reverse(ContainerSorter(out)))
+
+	w.Header().Set("Content-Type", "application/json")
 	json.NewEncoder(w).Encode(out)
 }
 
@@ -143,6 +147,8 @@ func getContainerJSON(c *context, w http.ResponseWriter, r *http.Request) {
 
 		// insert node IP
 		data = bytes.Replace(data, []byte("\"HostIp\":\"0.0.0.0\""), []byte(fmt.Sprintf("\"HostIp\":%q", container.Node.IP)), -1)
+
+		w.Header().Set("Content-Type", "application/json")
 		w.Write(data)
 	}
 }
@@ -170,6 +176,8 @@ func postContainersCreate(c *context, w http.ResponseWriter, r *http.Request) {
 		httpError(w, err.Error(), http.StatusInternalServerError)
 		return
 	}
+
+	w.Header().Set("Content-Type", "application/json")
 	fmt.Fprintf(w, "{%q:%q}", "Id", container.Id)
 	return
 }

api/utils.go

@@ -41,6 +41,16 @@ func getContainerFromVars(c *context, vars map[string]string) (*cluster.Containe
 	return nil, errors.New("Not found")
 }
 
+// from https://github.com/golang/go/blob/master/src/net/http/httputil/reverseproxy.go#L82
+func copyHeader(dst, src http.Header) {
+	for k, vv := range src {
+		for _, v := range vv {
+			fmt.Println(k, v)
+			dst.Add(k, v)
+		}
+	}
+}
+
 func proxy(tlsConfig *tls.Config, container *cluster.Container, w http.ResponseWriter, r *http.Request) error {
 	// Use a new client for each request
 	client, scheme := newClientAndScheme(tlsConfig)
@@ -56,6 +66,8 @@ func proxy(tlsConfig *tls.Config, container *cluster.Container, w http.ResponseW
 	if err != nil {
 		return err
 	}
+
+	copyHeader(w.Header(), resp.Header)
 	w.WriteHeader(resp.StatusCode)
 	io.Copy(w, resp.Body)