From 00ea31f2f65526d9338f41f15d615db6998ce360 Mon Sep 17 00:00:00 2001
From: Mechiel Lukkien <mechiel@ueber.net>
Date: Tue, 21 Mar 2023 09:25:49 +0100
Subject: [PATCH] do not generate http status 502 for canceled http requests

do log them with level debug, and print the error in the http access log line.
---
 http/web.go       | 6 +++++-
 http/webserver.go | 5 +++++
 2 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/http/web.go b/http/web.go
index 4137d07..86c4ad4 100644
--- a/http/web.go
+++ b/http/web.go
@@ -152,7 +152,11 @@ func (w *loggingWriter) Done() {
 			tlsinfo = "(other)"
 		}
 	}
-	xlog.WithContext(w.R.Context()).Debugx("http request", w.WriteErr,
+	err := w.WriteErr
+	if err == nil {
+		err = w.R.Context().Err()
+	}
+	xlog.WithContext(w.R.Context()).Debugx("http request", err,
 		mlog.Field("httpaccess", ""),
 		mlog.Field("handler", w.Handler),
 		mlog.Field("method", method),
diff --git a/http/webserver.go b/http/webserver.go
index 666ea64..fafb7d9 100644
--- a/http/webserver.go
+++ b/http/webserver.go
@@ -1,6 +1,7 @@
 package http
 
 import (
+	"context"
 	"errors"
 	"fmt"
 	htmltemplate "html/template"
@@ -415,6 +416,10 @@ func HandleForward(h *config.WebForward, w http.ResponseWriter, r *http.Request,
 	proxy.FlushInterval = time.Duration(-1) // Flush after each write.
 	proxy.ErrorLog = golog.New(mlog.ErrWriter(mlog.New("net/http/httputil").WithContext(r.Context()), mlog.LevelDebug, "reverseproxy error"), "", 0)
 	proxy.ErrorHandler = func(w http.ResponseWriter, r *http.Request, err error) {
+		if errors.Is(err, context.Canceled) {
+			log().Debugx("forwarding request to backend webserver", err, mlog.Field("url", r.URL))
+			return
+		}
 		log().Errorx("forwarding request to backend webserver", err, mlog.Field("url", r.URL))
 		if os.IsTimeout(err) {
 			http.Error(w, "504 - gateway timeout"+recvid(), http.StatusGatewayTimeout)