Add logs when error is generated in error handler

vendor/github.com/vulcand/oxy/forward/rewrite.go

@@ -85,6 +85,10 @@ func forwardedPort(req *http.Request) string {
 		return port
 	}
 
+	if req.Header.Get(XForwardedProto) == "https" || req.Header.Get(XForwardedProto) == "wss" {
+		return "443"
+	}
+
 	if req.TLS != nil {
 		return "443"
 	}

vendor/github.com/vulcand/oxy/utils/handler.go

@@ -4,6 +4,8 @@ import (
 	"io"
 	"net"
 	"net/http"
+
+	log "github.com/sirupsen/logrus"
 )
 
 type ErrorHandler interface {
@@ -28,6 +30,7 @@ func (e *StdHandler) ServeHTTP(w http.ResponseWriter, req *http.Request, err err
 	}
 	w.WriteHeader(statusCode)
 	w.Write([]byte(http.StatusText(statusCode)))
+	log.Debugf("'%d %s' caused by: %v", statusCode, http.StatusText(statusCode), err)
 }
 
 type ErrorHandlerFunc func(http.ResponseWriter, *http.Request, error)