[logback-user] Trouble setting up logback in tomcat.

Sebastien Pennec sebastien at qos.ch
Wed Dec 20 14:29:39 CET 2006

Hello Marten,

I read your email again and would like to clarify a few more points about my previous 

The information I gave you should allow you to configure and use logback as your 
logging implementation, for your application.

I've seen that you put commons-logging-1.1.jar *and* jcl104-over-slf4j-1.1.0-RC1.jar 
in commons/lib directory. This will probably lead to unexpected behaviour, no matter 
how it is used. These two jars contains the same classes, up to a certain extent. 
jcl104-over-slf4j.jar is used to intercept calls to commons-logging and redirect them 
to a chosen SLF4J implementation. Having both commons-logging-1.1.jar and 
jcl104-over-slf4j.jar in the same classpath will provide you with two implementations 
of the same classes: one that redirects to SLF4J and the usual commons-logging 
implementation. If your application uses logback, but some other application that 
runs under Tomcat (or any dependency of your application) uses commons-logging, your 
might use jcl104-over-slf4j.jar to intercept these calls and redirect them to any 
SLF4J implementation.

On the other hand, intercepting Tomcat's own *internal* logging is something that we 
do not recommand at this time.


Marten Deinum wrote:
> For my current project I would like to switch out all the logging which is
> currently being done by log4j and here en there by commons-logging to one
> framework. After some searching I discoverd SLF4J and Logback as the
> successor to log4j. In your code I swapped out all the log4j and
> commons-logging to the SLF4J api and I want to use Logback as my logger. I
> converted our log4j.properties file with the configuration converter on the
> website, so I assume that is correct.
> In the tomcat directory I have the following logging libs (I want tomcat to
> use SLF4J to)
> commons/lib/commons-logging-1.1.jar
> commons/lib/jcl104-over-slf4j-1.1.0-RC1.jar
> commons/classes/logback.xml
> In our webapplication (which is a packaged war and doesn't get unpacked!) I
> have
> WEB-INF/lib/slf4j-api-1.1.0-RC1.jar
> WEB-INF/lib/logback-classic-0.7.jar
> WEB-INF/lib/logback-core-0.7.jar
> WEB-INF/classes/logback.xml
> The contents of the logback.xml in the commons directory just contains a
> simple ConsoleAppender and is configured to WARN level.
> The file in the WEB-INF directory is configured as a file which should be
> written to c:\logs\mylog.log, configured different levels for different
> packages we use.
> However logback isn't getting picked up, everything is being logged by the
> java.util classes (as it appears thatone is being initialized by tomcat
> instead of the logback logger). 
> I tried different configurations, all the logback/slf4j jars in the
> commons/lib and one config file in commons/classes. Different jars in
> commons/lib and WEB-INF/lib but until now everytime with the same result,
> only logging to JUL and nothing to logback and my configured logfile. 
> Currently I'm at a loss on what to do and how to make it work. I need some
> assistance with this.
> Kind Regards,
>  Marten

Sébastien Pennec
sebastien at qos.ch

Logback: The reliable, generic, fast and flexible logging framework for Java.

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