_.diff

diff --git a/proxyserver/main.go b/proxyserver/main.go
index cb3d7cb..0b921cc 100644
--- a/proxyserver/main.go
+++ b/proxyserver/main.go
@@ -44,6 +44,7 @@ type ProxyServer struct {
 	accountAutoCreate bool
 	proxyDirectClient *client.ProxyDirectClient
 	metricsCloser     io.Closer
+	debugResponses    bool
 }
 
 func (server *ProxyServer) Type() string {
@@ -145,7 +146,7 @@ func (server *ProxyServer) GetHandler(config conf.Config, metricsPrefix string)
 			{middleware.NewXlo, "filter:slo"},
 		}
 	}
-	pipeline := alice.New(middleware.NewContext(server.mc, server.logger, server.proxyDirectClient))
+	pipeline := alice.New(middleware.NewContext(server.debugResponses, server.mc, server.logger, server.proxyDirectClient))
 	for _, m := range middlewares {
 		mid, err := m.construct(config.GetSection(m.section), metricsScope)
 		if err != nil {
@@ -172,6 +173,7 @@ func GetServer(serverconf conf.Config, flags *flag.FlagSet) (string, int, srv.Se
 	server.logLevel = zap.NewAtomicLevel()
 	server.logLevel.UnmarshalText([]byte(strings.ToLower(logLevelString)))
 	server.accountAutoCreate = serverconf.GetBool("app:proxy-server", "account_autocreate", false)
+	server.debugResponses = serverconf.GetBool("debug", "debug_x_source_code", false)
 	if server.logger, err = srv.SetupLogger("proxy-server", &server.logLevel, flags); err != nil {
 		return "", 0, nil, nil, fmt.Errorf("Error setting up logger: %v", err)
 	}
diff --git a/proxyserver/middleware/context.go b/proxyserver/middleware/context.go
index ba67812..291ba55 100644
--- a/proxyserver/middleware/context.go
+++ b/proxyserver/middleware/context.go
@@ -21,6 +21,7 @@ import (
 	"fmt"
 	"io"
 	"net/http"
+	"runtime"
 	"strconv"
 	"strings"
 	"sync"
@@ -73,6 +74,7 @@ type ProxyContextMiddleware struct {
 	log               srv.LowLevelLogger
 	Cache             ring.MemcacheRing
 	proxyDirectClient *client.ProxyDirectClient
+	debugResponses    bool
 }
 
 type ProxyContext struct {
@@ -327,6 +329,13 @@ func (m *ProxyContextMiddleware) ServeHTTP(writer http.ResponseWriter, request *
 				w.Header().Set("Www-Authenticate", "Swift realm=\"unknown\"")
 			}
 		}
+
+		if m.debugResponses {
+			buf := make([]byte, 1024)
+			runtime.Stack(buf, false)
+			w.Header().Set("X-Source-Code", string(buf))
+		}
+
 		ctx.responseSent = true
 		ctx.status = status
 		return status
@@ -335,13 +344,14 @@ func (m *ProxyContextMiddleware) ServeHTTP(writer http.ResponseWriter, request *
 	m.next.ServeHTTP(newWriter, request)
 }
 
-func NewContext(mc ring.MemcacheRing, log srv.LowLevelLogger, proxyDirectClient *client.ProxyDirectClient) func(http.Handler) http.Handler {
+func NewContext(debug bool, mc ring.MemcacheRing, log srv.LowLevelLogger, proxyDirectClient *client.ProxyDirectClient) func(http.Handler) http.Handler {
 	return func(next http.Handler) http.Handler {
 		return &ProxyContextMiddleware{
 			Cache:             mc,
 			log:               log,
 			next:              next,
 			proxyDirectClient: proxyDirectClient,
+			debugResponses:    debug,
 		}
 	}
 }