Generate Stack Traces for http response with status code zero

When we spit out a http reponse with a `0` http status code we
should log a trace back so we can easily find where things went wrong.

Change-Id: Ic2aadec3a3de85fbdf64da66d6d12e3c631f409d

Kubernetes-commit: 72792d59f46f822cf360e797d886e582a6a2dc60

pkg/server/filters/wrap.go

@@ -25,6 +25,17 @@ import (
 	"k8s.io/apiserver/pkg/server/httplog"
 )
 
+func badHTTPResponse() httplog.StacktracePred {
+	return func(status int) bool {
+		// http status code should not be zero
+		if status == 0 {
+			klog.Errorf("Bad HTTP Response - status is zero")
+			return true
+		}
+		return false
+	}
+}
+
 // WithPanicRecovery wraps an http Handler to recover and log panics.
 func WithPanicRecovery(handler http.Handler) http.Handler {
 	return withPanicRecovery(handler, func(w http.ResponseWriter, req *http.Request, err interface{}) {
@@ -39,7 +50,7 @@ func withPanicRecovery(handler http.Handler, crashHandler func(http.ResponseWrit
 			crashHandler(w, req, err)
 		})
 
-		logger := httplog.NewLogged(req, &w)
+		logger := httplog.NewLogged(req, &w).StacktraceWhen(badHTTPResponse())
 		defer logger.Log()
 
 		// Dispatch to the internal handler