[TimWolla]

I was the person creating the patch. For now all it does is compiling in support for `Type=notify` (using sd_notify [1]) in the unit file: haproxy is able to notify systemd when it completed the `start` or the `reload`.

In the future this could be extended to support systemd's socket passing and status messages. The latter allowing you to show a short string in `systemctl status haproxy`. See this example for php-fpm:

    [root@example~]systemctl status php7.0-fpm.service 
    ● php7.0-fpm.service - The PHP 7.0 FastCGI Process Manager
       Loaded: loaded (/lib/systemd/system/php7.0-fpm.service; enabled)
       Active: active (running) since Sat 2017-11-25 13:28:22 CET; 1 day 8h ago
         Docs: man:php-fpm7.0(8)
     Main PID: 4624 (php-fpm7.0)
       Status: "Processes active: 3, idle: 29, Requests: 1203613, slow: 545, Traffic: 10.1req/sec"
    *snip*

See the mailing list thread for the full discussion of the feature: https://www.mail-archive.com/[e-mail]/msg27874.h...

[1] https://www.freedesktop.org/software/systemd/man/sd_notify.h...