[Canary] lib: monkey: Import afunix patched bundled canary commit of libevent

[cosmo0920]

THIS IS CANARY PR. DO NOT MERGE.

With this importing AF_UNIX patch on libevent, we can completely eliminate the usages of tcp lookbacked socketpair in libevent's event system in Windows.
monkey/monkey#439

The previous canary still has some of the usages of local loopbacks but in this PR, there's no listeners of local loopback except for explicitly listening addresses.

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Enter [N/A] in the box, if an item is not applicable to your change.

Testing
Before we can approve your change; please submit the following in a comment:

• Example configuration file for the change

PS>bin/fluent-bit -i dummy -o stdout -H -P 2021 -v

• Debug log output from testing the change

Fluent Bit v5.0.6
* Copyright (C) 2015-2026 The Fluent Bit Authors
* Fluent Bit is a CNCF graduated project under the Fluent organization
* https://fluentbit.io

______ _                  _    ______ _ _           _____  _____
|  ___| |                | |   | ___ (_) |         |  ___||  _  |
| |_  | |_   _  ___ _ __ | |_  | |_/ /_| |_  __   _|___ \ | |/' |
|  _| | | | | |/ _ \ '_ \| __| | ___ \ | __| \ \ / /   \ \|  /| |
| |   | | |_| |  __/ | | | |_  | |_/ / | |_   \ V //\__/ /\ |_/ /
\_|   |_|\__,_|\___|_| |_|\__| \____/|_|\__|   \_/ \____(_)\___/


[2026/05/20 14:41:34.376] [ info] Configuration:
[2026/05/20 14:41:34.377] [ info]  flush time     | 1.000000 seconds
[2026/05/20 14:41:34.377] [ info]  grace          | 5 seconds
[2026/05/20 14:41:34.377] [ info]  daemon         | 0
[2026/05/20 14:41:34.377] [ info] ___________
[2026/05/20 14:41:34.377] [ info]  inputs:
[2026/05/20 14:41:34.377] [ info]      dummy
[2026/05/20 14:41:34.377] [ info] ___________
[2026/05/20 14:41:34.377] [ info]  filters:
[2026/05/20 14:41:34.377] [ info] ___________
[2026/05/20 14:41:34.377] [ info]  outputs:
[2026/05/20 14:41:34.377] [ info]      stdout.0
[2026/05/20 14:41:34.377] [ info] ___________
[2026/05/20 14:41:34.377] [ info]  collectors:
[2026/05/20 14:41:34.380] [ info] [fluent bit] version=5.0.6, commit=da72511d82, pid=14056
[2026/05/20 14:41:34.380] [debug] [engine] maxstdio set: 512
[2026/05/20 14:41:34.380] [debug] [engine] coroutine stack size: 98302 bytes (96.0K)
[2026/05/20 14:41:34.382] [ info] [storage] ver=1.5.4, type=memory, sync=normal, checksum=off, max_chunks_up=128
[2026/05/20 14:41:34.382] [ info] [simd    ] disabled
[2026/05/20 14:41:34.382] [ info] [cmetrics] version=2.1.4
[2026/05/20 14:41:34.382] [ info] [ctraces ] version=0.7.1
[2026/05/20 14:41:34.383] [ info] [input:dummy:dummy.0] initializing
[2026/05/20 14:41:34.383] [ info] [input:dummy:dummy.0] storage_strategy='memory' (memory only)
[2026/05/20 14:41:34.383] [debug] [dummy:dummy.0] created event channels: read=1008 write=1020
[2026/05/20 14:41:34.384] [debug] [stdout:stdout.0] created event channels: read=796 write=1036
[2026/05/20 14:41:34.389] [debug] [downstream] listening on 0.0.0.0:2021
[2026/05/20 14:41:34.389] [ info] [http_server] listen iface=0.0.0.0 tcp_port=2021
[2026/05/20 14:41:34.389] [ info] [sp] stream processor started
[2026/05/20 14:41:34.390] [ info] [output:stdout:stdout.0] worker #0 started
[2026/05/20 14:41:34.391] [ info] [engine] Shutdown Grace Period=5, Shutdown Input Grace Period=2
[2026/05/20 14:41:36.401] [debug] [task] created task=0000022A60BC5480 id=0 OK
[2026/05/20 14:41:36.401] [debug] [output:stdout:stdout.0] task_id=0 assigned to thread #0
[0] dummy.0: [[1779255695.379084400, {}], {"message"=>"dummy"}]
[2026/05/20 14:41:36.401] [debug] [out flush] cb_destroy coro_id=0
[2026/05/20 14:41:36.401] [debug] [task] destroy task=0000022A60BC5480 (task_id=0)
[2026/05/20 14:41:37.385] [debug] [task] created task=0000022A60BC5160 id=0 OK
[0] dummy.0: [[1779255696.401601200, [2026/05/20 14:41:37.385] [debug] [output:stdout:stdout.0] task_id=0 assigned to thread #0
{}], {"message"=>"dummy"}]
[2026/05/20 14:41:37.386] [debug] [out flush] cb_destroy coro_id=1
[2026/05/20 14:41:37.386] [debug] [task] destroy task=0000022A60BC5160 (task_id=0)
[2026/05/20 14:41:38.383] [debug] [task] created task=0000022A60BC5200 id=0 OK
[2026/05/20 14:41:38.383] [debug] [output:stdout:stdout.0] task_id=0 assigned to thread #0
[0] dummy.0: [[1779255697.386107300, {}], {"message"=>"dummy"}]
[2026/05/20 14:41:38.383] [debug] [out flush] cb_destroy coro_id=2
[2026/05/20 14:41:38.383] [debug] [task] destroy task=0000022A60BC5200 (task_id=0)
[2026/05/20 14:41:39.392] [debug] [task] created task=0000022A60BC5020 id=0 OK
[0] dummy.0: [[1779255698.383753200, {}], [2026/05/20 14:41:39.392] [debug] [output:stdout:stdout.0] task_id=0 assigned to thread #0
{"message"=>"dummy"}]
[2026/05/20 14:41:39.393] [debug] [out flush] cb_destroy coro_id=3
[2026/05/20 14:41:39.393] [debug] [task] destroy task=0000022A60BC5020 (task_id=0)
[2026/05/20 14:41:40.390] [debug] [task] created task=0000022A60BC4BC0 id=0 OK
[2026/05/20 14:41:40.390] [debug] [output:stdout:stdout.0] task_id=0 assigned to thread #0
[0] dummy.0: [[1779255699.393456500, {}], {"message"=>"dummy"}]
[2026/05/20 14:41:40.391] [debug] [out flush] cb_destroy coro_id=4
[2026/05/20 14:41:40.391] [debug] [task] destroy task=0000022A60BC4BC0 (task_id=0)
[2026/05/20 14:41:41.401] [debug] [task] created task=0000022A60BC4BC0 id=0 OK
[2026/05/20 14:41:41.401] [debug] [output:stdout:stdout.0] task_id=0 assigned to thread #0
[0] dummy.0: [[1779255700.390931100, {}], {"message"=>"dummy"}]
[2026/05/20 14:41:41.401] [debug] [out flush] cb_destroy coro_id=5
[2026/05/20 14:41:41.401] [debug] [task] destroy task=0000022A60BC4BC0 (task_id=0)
[2026/05/20 14:41:42.383] [debug] [task] created task=0000022A60BC5160 id=0 OK
[2026/05/20 14:41:42.383] [debug] [output:stdout:stdout.0] task_id=0 assigned to thread #0
[0] dummy.0: [[1779255701.401284800, {}], {"message"=>"dummy"}]
[2026/05/20 14:41:42.383] [debug] [out flush] cb_destroy coro_id=6
[2026/05/20 14:41:42.383] [debug] [task] destroy task=0000022A60BC5160 (task_id=0)
[2026/05/20 14:41:43.378] [debug] [task] created task=0000022A60BC4BC0 id=0 OK
[0] dummy.0: [[[2026/05/20 14:41:43.378] [debug] [output:stdout:stdout.0] task_id=0 assigned to thread #0
1779255702.383773500, {}], {"message"=>"dummy"}]
[2026/05/20 14:41:43.379] [debug] [out flush] cb_destroy coro_id=7
[2026/05/20 14:41:43.379] [debug] [task] destroy task=0000022A60BC4BC0 (task_id=0)
[2026/05/20 14:41:44.389] [debug] [task] created task=0000022A60BC4F80 id=0 OK
[0] dummy.0: [[1779255703.379145100, {[2026/05/20 14:41:44.389] [debug] [output:stdout:stdout.0] task_id=0 assigned to thread #0
}], {"message"=>"dummy"}]
[2026/05/20 14:41:44.390] [debug] [out flush] cb_destroy coro_id=8
[2026/05/20 14:41:44.390] [debug] [task] destroy task=0000022A60BC4F80 (task_id=0)
[2026/05/20 14:41:45.399] [debug] [task] created task=0000022A60BC4BC0 id=0 OK
[2026/05/20 14:41:45.399] [debug] [output:stdout:stdout.0] task_id=0 assigned to thread #0
[0] dummy.0: [[1779255704.389821400, {}], {"message"=>"dummy"}]
[2026/05/20 14:41:45.399] [debug] [out flush] cb_destroy coro_id=9
[2026/05/20 14:41:45.399] [debug] [task] destroy task=0000022A60BC4BC0 (task_id=0)
[2026/05/20 14:41:45] [engine] caught signal (SIGINT)
[2026/05/20 14:41:46.380] [debug] [task] created task=0000022A60BC4BC0 id=0 OK
[0] dummy.0: [[1779255705.399199600, [2026/05/20 14:41:46.380] [debug] [output:stdout:stdout.0] task_id=0 assigned to thread #0
{}], {"message"=>"dummy"}]
[2026/05/20 14:41:46.381] [debug] [out flush] cb_destroy coro_id=10
[2026/05/20 14:41:46.381] [debug] [task] destroy task=0000022A60BC4BC0 (task_id=0)
[2026/05/20 14:41:46.507] [debug] [task] created task=0000022A60BC4BC0 id=0 OK
[0] dummy.0: [[1779255706.381411500, {[2026/05/20 14:41:46.507] [debug] [output:stdout:stdout.0] task_id=0 assigned to thread #0
}], [2026/05/20 14:41:46.507] [ warn] [engine] service will shutdown in max 5 seconds
[2026/05/20 14:41:46.507] [debug] [engine] task 0 already scheduled to run, not re-scheduling it.
{[2026/05/20 14:41:46.507] [ info] [engine] pausing all inputs..
"message"=>"[2026/05/20 14:41:46.507] [ info] [input] pausing dummy.0
dummy"}]
[2026/05/20 14:41:46.507] [debug] [out flush] cb_destroy coro_id=11
[2026/05/20 14:41:46.508] [debug] [task] destroy task=0000022A60BC4BC0 (task_id=0)
[2026/05/20 14:41:47.521] [ info] [engine] service has stopped (0 pending tasks)
[2026/05/20 14:41:47.521] [ info] [input] pausing dummy.0
[2026/05/20 14:41:47.521] [ info] [output:stdout:stdout.0] thread worker #0 stopping...
[2026/05/20 14:41:47.521] [ info] [output:stdout:stdout.0] thread worker #0 stopped

Experiment result

Plus, we got with Get-NetTCPConnection Cmdlet:

PS> Get-NetTCPConnection -OwningProcess <modified fluent-bit pid>

LocalAddress                        LocalPort RemoteAddress                       RemotePort State       AppliedSetting
------------                        --------- -------------                       ---------- -----       --------------
0.0.0.0                             2021      0.0.0.0                             0          Listen

• Attached Valgrind output that shows no leaks or memory corruption was found

If this is a change to packaging of containers or native binaries then please confirm it works for all targets.

• Run local packaging test showing all targets (including any new ones) build.
• Set ok-package-test label to test for all targets (requires maintainer to do).

Documentation

• Documentation required for this feature

Backporting

• Backport to latest stable release.

---

Fluent Bit is licensed under Apache 2.0, by submitting this pull request I understand that this code will be released under the terms of that license.

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✨ Finishing Touches

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• Create PR with unit tests
• Commit unit tests in branch cosmo0920-canary-libevent-monkey-afunix-socketpair-patch-on-windows

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