That's right: there is no GELF source in syslog-ng. However, you should be able to send logs from Graylog using one of the syslog protocols, and those are pretty well supported by syslog-ng 🙂
From: syslog-ng <syslog-ng-bounces@lists.balabit.hu> on behalf of Steve Bernacki <steve@copacetic.net> Sent: Wednesday, August 21, 2024 13:13 To: Syslog-ng users' and developers' mailing list <syslog-ng@lists.balabit.hu>; Roberto Carna <robertocarna36@gmail.com> Subject: Re: [syslog-ng] Send GELF log messages to Syslog-NG server
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While syslog-ng can send logs in GELF format, I don't see anything in
the documentation about it being able to receive (accept) them in this
format.