haproxy/reg-tests
Alexander Stephan 64383e655b BUG/MEDIUM: cli: fix master CLI connection slot leak on client disconnect
In master-worker mode the master CLI proxy (mworker_proxy) has a
hardcoded maxconn of 10. When a client connects to the master CLI
socket and issues a command that gets forwarded to an unresponsive
worker (e.g. one that is stuck or very slow), the connection hangs
waiting for the worker's response. If the client then disconnects
(timeout, Ctrl-C, etc.), the connection slot is never released because
the client-side FIN is never acknowledged by the unresponsive worker.

After 10 such leaked slots the master CLI socket becomes completely
unreachable, returning "Resource temporarily unavailable" to any new
connection attempt. In containerized deployments this means readiness
probes start failing and the pod gets restarted.

The fix adds a timeout server-fin of 1s to the mworker_proxy. When
the client disconnects while waiting for a worker response, this
timeout ensures the dangling backend connection is cleaned up after
1s, freeing the connection slot. This does not affect normal CLI
operations since the timeout only starts after the client has already
closed its side of the connection.

A regression test is included that blocks the worker CLI thread using
"debug dev delay" with nbthread 1, fills all 10 master CLI slots,
waits for client-side timeouts, then verifies a new connection still
succeeds.

This fixes GH issue #3351.

This should be backported to all stable branches.

Co-authored-by: Martin Strenge <github@trixer.net>
Co-authored-by: William Lallemand <wlallemand@haproxy.com>
2026-04-30 17:06:19 +02:00
..

                 * Regression testing for HAProxy with VTest *


This little README file is about how to compile and run vtest test case files (VTC files)
to test HAProxy for any regression.

To do so, you will have to compile vtest program sources which depends on
Varnish cache application sources. vtest, formerly varnishtest, is a very useful
program which has been developed to test Varnish cache application. vtest has been
modified in collaboration with Varnish cache conceptor Poul-Henning Kamp to support
HAProxy in addition to Varnish cache.

See also: doc/regression-testing.txt

* vtest compilation *

    $ git clone https://github.com/vtest/VTest2

    $ cd VTest

    $ make vtest

  Then vtest program may be found at the root directory of vtest sources directory.
  The Varnish cache manuals are located in 'man' directory of Varnish cache sources
  directory. You will have to have a look at varnishtest(7) and vtc(7) manuals to
  use vtest.

  Some information may also be found in doc/regression-testing.txt in HAProxy
  sources.

  Note that VTC files for Varnish cache may be found in bin/varnishtest/tests directory
  of Varnish cache sources directory which may be found here:
  https://github.com/varnishcache/varnish-cache


* vtest execution *

  You must set HAPROXY_PROGRAM environment variable to give the location
  of the HAProxy program to test to vtest:

    $ HAPROXY_PROGRAM=<my haproxy program> vtest ...

  The HAProxy VTC files found in HAProxy sources may be run with the reg-tests
  Makefile target. You must set the VTEST_PROGRAM environment variable to
  give the location of the vtest program which has been previously compiled.

    $ VTEST_PROGRAM=<my vtest program> make reg-tests

  "reg-tests" Makefile target run scripts/run-regtest.sh script.
  To get more information about this script run it with --help option.

  Note that vtest is run with -t10 and -l option. -l option is to keep
  keep vtest temporary directory in case of failed test cases. core files
  may be found in this directory (if enabled by ulimit).


* vtest patches for HAProxy VTC files *

  When producing a patch to add a VTC regression testing file to reg-tests directory,
  please follow these simple rules:

    - If your VTC file needs others files, if possible, use the same basename as that
      of the VTC file,
    - Put these files in a directory with the same name as the code area concerned
      by the bug ('peers', 'lua', 'acl' etc).

Please note that most tests use a common set of timeouts defined by the
environment variable HAPROXY_TEST_TIMEOUT. As much as possible, for regular I/O
(i.e. not errors), please try to reuse that setting so that the value may
easily be adjusted when running in some particularly slow environments, or be
shortened to fail faster on developers' machines.