Hi.
I need to debug a network issue, for that have I used HAProxy with lua, what
else :-).
The Scenario:
The Jakarta HTTPClient send a REST request to a REST Server and until the server
isn't finished with there task is no traffic passed on the network, after ~4/5
minutes the Client shows the SocketException below and set a error state.
```
An error occurred - while sending the request
java.net.SocketException: Connection reset
```
My assumption is that some network components on the way closes some sockets.
With the great HAProxy was it now easily possible to reproduce the "waiting"
request without do debug the REST Server.
Now after the setup is running I get this Alert from HAProxy/Lua
```
Connect from 10.129.10.13:42258 to 10.129.42.86:4711 (http-in/HTTP)
>>> TCP ACTION
416
Lua function 'my_tcp-sleep': yield not allowed.
[ALERT] (8) : Lua function 'my_tcp-sleep': yield not allowed.
```
What's wrong and how can I fix this?
Do I need the lua sleep or is the line
tcp-request inspect-delay 6m
enough for the simulation?
The HAProxy config.
```
# cat haproxy-minimal.txt
# /usr/local/etc/haproxy/haproxy.cfg
global
log stdout format raw daemon
# lua settings
tune.lua.session-timeout 6m
tune.lua.bool-sample-conversion normal
lua-load /mnt/my_tcp_sleep.lua
defaults
mode http
log global
timeout connect 5s
timeout client 5h
timeout server 5h
listen http-in
bind *:4711
tcp-request inspect-delay 6m
tcp-request content lua.my_tcp-sleep
http-request return status 200
```
The lua sleep function is mainly copied from
https://discourse.haproxy.org/t/lua-tcp-request-content-action-timeout-on-core-sleep/5179
```
# cat my_tcp_sleep.lua
local function my_tcp_action(txn)
txn.Info(txn, ">>> TCP ACTION")
local request_buffer_content_len = txn.req:get_in_len()
core.Debug(request_buffer_content_len)
-- dup not allowed
-- local request_buffer_content = txn.req:dup()
-- core.Debug(tostring(request_buffer_content))
-- 6 Min
core.sleep(3600)
txn.Info(txn, ">>> done sleeping")
end
core.register_action('my_tcp-sleep', {'tcp-req'}, my_tcp_action, 0)
```
I use the Container Image "haproxy:3.1-bookworm"
```
$ haproxy -vv
HAProxy version 3.1.5-076df02 2025/02/20 - https://haproxy.org/
Status: stable branch - will stop receiving fixes around Q1 2026.
Known bugs: http://www.haproxy.org/bugs/bugs-3.1.5.html
Running on: Linux 5.14.0-427.44.1.el9_4.x86_64 #1 SMP PREEMPT_DYNAMIC Fri Nov 1
14:40:56 EDT 2024 x86_64
Build options :
TARGET = linux-glibc
CC = cc
CFLAGS = -O2 -g -fwrapv
OPTIONS = USE_GETADDRINFO=1 USE_OPENSSL=1 USE_LUA=1 USE_PROMEX=1 USE_PCRE2=1
USE_PCRE2_JIT=1
DEBUG =
Feature list : -51DEGREES +ACCEPT4 +BACKTRACE -CLOSEFROM +CPU_AFFINITY +CRYPT_H
-DEVICEATLAS +DL -ENGINE +EPOLL -EVPORTS +GETADDRINFO -KQUEUE -LIBATOMIC
+LIBCRYPT +LINUX_CAP +LINUX_SPLICE +LINUX_TPROXY +LUA +MATH -MEMORY_PROFILING
+NETFILTER +NS -OBSOLETE_LINKER +OPENSSL -OPENSSL_AWSLC -OPENSSL_WOLFSSL -OT
-PCRE +PCRE2 +PCRE2_JIT -PCRE_JIT +POLL +PRCTL -PROCCTL +PROMEX
-PTHREAD_EMULATION -QUIC -QUIC_OPENSSL_COMPAT +RT +SHM_OPEN +SLZ +SSL
-STATIC_PCRE -STATIC_PCRE2 +TFO +THREAD +THREAD_DUMP +TPROXY -WURFL -ZLIB
Default settings :
bufsize = 16384, maxrewrite = 1024, maxpollevents = 200
Built with multi-threading support (MAX_TGROUPS=16, MAX_THREADS=256,
default=32).
Built with OpenSSL version : OpenSSL 3.0.15 3 Sep 2024
Running on OpenSSL version : OpenSSL 3.0.15 3 Sep 2024
OpenSSL library supports TLS extensions : yes
OpenSSL library supports SNI : yes
OpenSSL library supports : TLSv1.0 TLSv1.1 TLSv1.2 TLSv1.3
OpenSSL providers loaded : default
Built with Lua version : Lua 5.4.4
Built with the Prometheus exporter as a service
Built with network namespace support.
Built with libslz for stateless compression.
Compression algorithms supported : identity("identity"), deflate("deflate"),
raw-deflate("deflate"), gzip("gzip")
Built with transparent proxy support using: IP_TRANSPARENT IPV6_TRANSPARENT
IP_FREEBIND
Built with PCRE2 version : 10.42 2022-12-11
PCRE2 library supports JIT : yes
Encrypted password support via crypt(3): yes
Built with gcc compiler version 12.2.0
Available polling systems :
epoll : pref=300, test result OK
poll : pref=200, test result OK
select : pref=150, test result OK
Total: 3 (3 usable), will use epoll.
Available multiplexer protocols :
(protocols marked as <default> cannot be specified using 'proto' keyword)
h2 : mode=HTTP side=FE|BE mux=H2 flags=HTX|HOL_RISK|NO_UPG
<default> : mode=HTTP side=FE|BE mux=H1 flags=HTX
h1 : mode=HTTP side=FE|BE mux=H1 flags=HTX|NO_UPG
fcgi : mode=HTTP side=BE mux=FCGI flags=HTX|HOL_RISK|NO_UPG
<default> : mode=SPOP side=BE mux=SPOP flags=HOL_RISK|NO_UPG
spop : mode=SPOP side=BE mux=SPOP flags=HOL_RISK|NO_UPG
<default> : mode=TCP side=FE|BE mux=PASS flags=
none : mode=TCP side=FE|BE mux=PASS flags=NO_UPG
Available services : prometheus-exporter
Available filters :
[BWLIM] bwlim-in
[BWLIM] bwlim-out
[CACHE] cache
[COMP] compression
[FCGI] fcgi-app
[SPOE] spoe
[TRACE] trace
```
Regards
Alex
