Small correction I'm still on 1.8.20.
I have since managed to do a tcpdump on the HAProxy box for the backend
connection to the web/socket server.
I can see that HAProxy forwards the connection upgrade request, the
connection is upgraded and I can see websocket traffic (viewing dump in

The connection still times out based on the server timeout and not the
tunnel timeout setting.

How can I debug this on the HAProxy side?


-----Original Message-----
From: Rabie Van Der Merwe <>
Sent: Friday, 27 September 2019 12:14
To: '' <>
Subject: WebSocket connection upgrade not using tunnel timeout


I'm on 1.8.21 and have a webapp that uses websockets.
The application works, but the app complains very quickly that the
connection to the server has been lost.
On the second line we get "sD--" Which is:
sD      The server did not send nor acknowledge any data for as long as
the "timeout server" setting during the data phase. This is often caused
by too short timeouts on L4 equipments before the server (firewalls,
load-balancers, .), as well as keep-alive sessions maintained between the
client and the server expiring first on haproxy.

I have added a tunnel timeout statement, however I'm unsure if haproxy is
aware of this and if it is why is it still timing out on server timeout? I
have noticed that I can increase the server timeout which would delay the
disconnect, however this is not a solution.

Any suggestions? How can I check to see if haproxy 'sees' the connection

Sep 27 11:43:52 localhost haproxy[22504]:
[27/Sep/2019:11:43:52.201] mainhttps~ smartcm01/apxblvcm01 0/0/0/7/7 200
1217 - - ---- 9/9/1/2/0 0/0 {|} "GET /nui/images/settings.gif HTTP/1.1"
Sep 27 11:44:51 localhost haproxy[22504]:
[27/Sep/2019:11:43:50.389] mainhttps~ smartcm01/apxblvcm01 0/0/1/7/61486
101 606 - - sD-- 3/3/0/0/0 0/0 {|} "GET /rest/events HTTP/1.1"
Sep 27 11:51:25 localhost haproxy[22504]:
[27/Sep/2019:11:51:25.423] mainhttps~ smartcm01/apxblvcm01 0/0/2/7/9 304
100 - - ---- 8/8/0/1/0 0/0 {|} "GET / HTTP/1.1"

Rabie van der Merwe

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