Logging with log4j on tomcat jruby-rack for a Rails 3 application

Question

I just spent the better part of 3 hours trying to get my Rails application logging with Log4j. I've finally got it working, but I'm not sure if what I did is correct. I tried various methods to no avail until my very last attempt. So I'm really looking for some validation here, perhaps some pointers and tips as well -- anything would be appreciated to be honest. I've summarized all my feeble methods into three attempts below. I'm hoping for some enlightenment on where I went wrong with each attempt -- even if it means I get ripped up.

Thanks for the help in advance!

System Specs

• Rails 3.0
• Windows Server 2008
• Log4j 1.2
• Tomact 6.0.29
• Java 6

Attempt 1 - Configured Tomcat to Use Log4J

I basically followed the guide on the Apache Tomcat website here. The steps are:

1. Create a log4j.properties file in $CATALINA_HOME/lib
2. Download and copy the log4j-x.y.z.jar into $CATALINA_HOME/lib
3. Replace $CATALINA_HOME/bin/tomcat-juli.jar with the tomcat-juli.jar from the Apache Tomcat Extras folder
4. Copy tomcat-juli-adapters.jar from the Apache Tomcat Extras folder into $CATALINA_HOME/lib
5. Delete $CATALINA_BASE/conf/logging.properties
6. Start Tomcat (as a service)

Expected Results According to the Guide

I should have seen a tomcat.log file in my $CATALINA_BASE/logs folder.

Actual Results

• No tomcat.log
• Saw three of the standard logs instead
  • jakarta_service_20101231.log
  • stderr_20101231.log
  • stdout_20101231.log

Question

• Shouldn't I have at least seen a tomcat.log file?

Attempt 2 - Use default Tomcat logging (commons-logging)

1. Reverted all the changes from the previous setup

2. Modified $CATALINA_BASE/conf/logging.properties by doing the following:

   1. Adding a setting for my application in the handlers line: 5rails3.org.apache.juli.FileHandler

   2. Adding Handler specific properties

      5rails3.org.apache.juli.FileHandler.level = FINE
      5rails3.org.apache.juli.FileHandler.directory = ${catalina.base}/logs
      5rails3.org.apache.juli.FileHandler.prefix = rails3.
      

   3. Adding Facility specific properties

      org.apache.catalina.core.ContainerBase.[Catalina].[localhost].[/rails3].level = INFO
      org.apache.catalina.core.ContainerBase.[Catalina].[localhost].[/rails3].handlers = 4host-manager.org.apache.juli.FileHandler
      

3. Modified my web.xml by adding the following context parameter as per the Logging section of the jruby-rack README (I also modified my warbler.rb accordingly, but I opted to change the web.xml directly to test things faster).

   <context-param>
     <param-name>jruby.rack.logging</param-name>
     <param-value>commons_logging</param-value>
   </context-param>
   

4. Restarted Tomcat

Results

• A log file was created (rails3.log), however there was no log information in the file.

Attempt 2A - Use Log4j with existing set up

I decided to give Log4j another whirl with this new web.xml setting.

1. Copied the log4j.jar into my WEB-INF/lib folder

2. Created a log4j.properties file and put it into WEB-INF/classes

   log4j.rootLogger=INFO, R
   log4j.logger.javax.servlet=DEBUG
   
   log4j.appender.R=org.apache.log4j.RollingFileAppender
   log4j.appender.R.File=${catalina.base}/logs/rails3.log
   log4j.appender.R.MaxFileSize=5036KB
   log4j.appender.R.MaxBackupIndex=4
   log4j.appender.R.layout=org.apache.log4j.PatternLayout
   log4j.appender.R.layout.ConversionPattern=%d{dd MMM yyyy HH:mm:ss} [%t] %-5p %c %x - %m%n
   

3. Restarted Tomcat

Results

Same as Attempt 2

NOTE: I used log4j.logger.javax.servlet=DEBUG because I read in the jruby-rack README that all logging output is automatically redirected to the javax.servlet.ServletContext#log method. So I thought this would capture it, but I was obviously wrong.

Question

1. Why didn't this work?
2. Isn't Log4J using the commons_logging API?

Attempt 3 - Tried out slf4j (WORKED)

A bit uncertain as to why Attempt 2A didn't work, I thought to myself, maybe I can't use commons_logging for the jruby.rack.logging parameter because it's probably not using commons_logging API... (but I was still not sure). I saw slf4j as an option. I have never heard of it and out of curiosity, I decided to look it up. After reading about it briefly, I thought it was as good of a shot as any and decided to try it out following the instructions here.

Continuing from the setup of Attempt 2A:

1. Copied slf4j-api-1.6.1.jar and slf4j-simple-1.6.1.jar into my WEB-INF/lib folder
2. I also copied slf4j-log4j12-1.6.1.jar into my WEB-INF/lib folder
3. Restarted Tomcat

And VIOLA! I now have logging information going into my rails3.log file.

So the big question is:

WTF?

Even though logging seems to be working now, I'm really not sure if what I did is right. So like I said earlier, I'm really looking for some validation more or less. I'd also appreciate any pointers/tips/advice if you have any. Thanks!

Answer 1

We also did various experiments and finally settled with slf4j option. Coming from Java background we knew slf4j, so we didn't go further.

<context-param>
   <param-name>jruby.rack.logging</param-name>
   <param-value>slf4j</param-value>
 </context-param>

btw, there is no need to copy slf4j-simple-1.6.1.jar into tomcat/lib or WEB-INF/lib when using slf4j-log4jxxx.jar