[logback-user] Custom appender: output of addWarn() not showing

Ton van Bart tonvanbart at gmail.com
Fri Jul 7 14:53:26 CEST 2023

Thank you for the tip, that was very helpful!
TBH I wasn't aware of StatusListeners... I added an OnConsoleStatusListener
in logback.xml, as I mentioned this appender is added to Kafka Connect -
which we have running in Kubernetes - and messages started showing up
(albeit with a delay, which I think is due to fact that I'm logging in the
callback passed to Kafka produce().
So, for my understanding, any statuses added during appender start() are
picked up and shown, but statuses added during append() are not shown
_unless_ you explicitly add a status listener, is that correct?

Thanks again for your help, kind regards, Ton

On Thu, Jul 6, 2023 at 1:00 PM Ceki Gülcü via logback-user <
logback-user at qos.ch> wrote:

> Hello Ton,
> Have you tried adding a statusListener on the command line?
> See https://logback.qos.ch/manual/configuration.html#logback.statusLC
> StatusListeners should work the same way in logback version 1.2.
> Let us know if this helps,
> --
> Ceki Gülcü
> Sponsoring SLF4J/logback/reload4j at https://github.com/sponsors/qos-ch
> On 7/5/2023 11:14 PM, Ton van Bart via logback-user wrote:
> > Hello,
> > I have created a custom Logback appender which sends the log events to a
> > Kafka topic. In order to verify if producing to Kafka was successful, I
> > check the result and do an addWarn("Failed to produce logging", e) if
> > there was an exception.
> > Similarly, I tried to add an addInfo("produced offset:" +
> > matadata.offset()) when a produce is successful.
> >
> > I'm using this appender in Kafka Connect, where I have wrapped it in an
> > AsyncAppender; however, neither message is showing. I also tried
> > printing to System.out / System.err from within the appender with the
> > same (lack of) result: during start up of Connect, I do see addInfo()
> > messages, but during normal processing, everything goes silent. No
> > messages appear on the topic so I assume something went wrong; when
> > testing the setup in a local docker compose, it works, so there must be
> > some problem somewhere.
> >
> > I understand that this may be due to the combination with Kafka Connect,
> > my question is: should I expect addInfo() etc. to show up in normal
> > appender processing (i.e. calling it from within append() or is this
> > internal logging for use only in appender start() ? What would be the
> > standard way for an appender to report errors during append()?
> >
> > Note: due to circumstances beyond my control, I'm currently stuck on
> > Logback 1.2.11 .
> >
> > Thanks in advance for any tips, kind regards, Ton
> >
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