Re: Log4j 1.2.x Customer Appender not used as "Plugin" by Log4j 1.2 Bridge

Comments below.

> On Mar 29, 2022, at 3:01 PM, Pablo Rogina <[email protected]> wrote:
> 
> Ralph, thank you for your reply.
> 
>> To be usable in your configuration a Log4j 1.2 Appender cannot be a Log4j2 plugin.
> Ok. It is not, as my CustomAppender extends RollingFileAppender (from
> Log4j v 1.2.x)
> 
>> You would configure it exactly as you do in log4j 1.x, via its class name.
> Ok. I think it's what I'm doing.
> This is the properties I'm using to configure my app logging:
> log4j.appender.MYAPPLOGFILE=com.mycompany.log4j.CustomAppender
> log4j.appender.MYAPPLOGFILE.Append=false
> log4j.appender.MYAPPLOGFILE.SpecialValue=ABC
> log4j.appender.MYAPPLOGFILE.HeaderVersion=1
> log4j.appender.MYAPPLOGFILE.File=logs/MyApp.log
> log4j.appender.MYAPPLOGFILE.MaxBackupIndex=19
> log4j.appender.MYAPPLOGFILE.MaxFileSize=2000KB
> log4j.appender.MYAPPLOGFILE.layout=org.apache.log4j.PatternLayout
> log4j.appender.MYAPPLOGFILE.layout.ConversionPattern=%d{[dd MMM yyyy
> HH\:mm\:ss,SSS]}[%t]\:%-5p\:%l -->%m%n
> log4j.rootLogger=INFO, MYAPPLOGFILE


For this can you run your application with -Dlog4j2.debug=true? I’d like to see what is happening.

> 
>> That said, Do you really need your custom RollingFileAppender? The RollingFileAppender
>> in Log4j 2 has many more options than Log4j 1 did.
> 
> Well, I also have a CustomAppender for Log4j 2 that resembles a
> RollingFileAppender, defined like this:
> 
> @Plugin(name = CustomAppender.PLUGIN_NAME, category =
> Core.CATEGORY_NAME, elementType = Appender.ELEMENT_TYPE, printObject =
> true)
> public final class CustomAppender extends
> AbstractOutputStreamAppender<RollingFileManager> {
> ...
> 
> however I also got the "Unable to load plugin class name ..." issue if
> using the CustomAppender v2.
> And I also find difficult to configure it via Properties using the
> Log4j 1.2 Bridge

Yes, that is understandable. The problem is that the Log4j 1 support cannot directly deal with 
a Log4j 2 Appender. It has to wrap it to make it look like a Log4j 1 Appender. So you could 
either create your own Builder that is similar to the other AppenderBuilders or you can define 
your custom Log4j.2 Appender in its own Log4j 2 configuration file and then merge it with your 
Log4j 1 configuration as a composite configuration - see https://logging.apache.org/log4j/2.x/manual/configuration.html#CompositeConfiguration <https://logging.apache.org/log4j/2.x/manual/configuration.html#CompositeConfiguration>.

Ralph