Re: how to use log4j-to-jul with log4j-web

Hi All:

Thank you all for your help and the good information about log4j-web and 
log4-core.

I already had my per-application logging configured in 
WEB-INF/logging.properties and all output is going to the same log file 
now that I've switched to log4j-to-jul.

Cheers,
Jason

On 6/2/2023 2:13 PM, Jason Guild wrote:
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> Hi All:
>
> I have a web application that uses log4j (v2.20) which runs inside
> Tomcat 9.x on Java 8.
>
> Currently, the WEB-INF/log4j2.xml configuration file in the application
> sends its output to a rolling file appender targeting a separate file on
> the file system, but what I'd like to do is make all log4j output go to
> the regular per-application log under ${catalina_base}/logs which is
> managed by the stock Tomcat JULI implementation.
>
> We now have the log4j-to-jul module which can adapt log4j 2 output back
> to java.util.logging.
> Similar to my understanding of the purpose for log4j-to-slf4j, it seems
> that log4j-to-jul is meant to be used as an implementation by itself for
> log4j-api and without log4j-core.
>
> The application currently uses log4j-web to get the all the essential
> setup for initializing log4j 2 under an application container. The
> log4j-web library appears to have a hard dependency on log4j-core.
>
> After adding log4j-to-jul to the application classpath, I can see that
> it is recognized:
>> Multiple logging implementations found:
>> Factory: org.apache.logging.log4j.core.impl.Log4jContextFactory,
>> Weighting: 10
>> Factory: org.apache.logging.log4j.tojul.JULLoggerContextFactory,
>> Weighting: 20
>
> But then the following error is reported:
>> ERROR StatusLogger LogManager returned an instance of
>> org.apache.logging.log4j.tojul.JULLoggerContextFactory which does not
>> implement org.apache.logging.log4j.core.impl.Log4jContextFactory.
>> Unable to initialize Log4j.
>
> In org.apache.logging.core.config.Configurator, line 47 there is a
> conditional that checks the return type of the logging implementation
> is-a Log4jContextFactory. The problem is then that
> JULLoggerContextFactory implements only LoggerContextFactory.
>
> I'd like to keep my tomcat container as stock as possible. Particularly,
> continuing to use the built-in JULI per-application logging and *not*
> switching the entire container to use log4j as its logging 
> implementation.
>
> Can anyone suggest how I can use log4j-to-jul successfully for my use 
> case?
>
> Thanks,
> Jason
>
>
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-- 
Jason Guild
Systems Programmer
Alaska Department of Transportation & Public Facilities
Statewide Administrative Services
820 E. 15th Ave.
Anchorage, Alaska 99501