Tomcat 7 Internal Logging with Log4j2 XML Configuration

Introduction:
Apache Tomcat 7 is a widely-used web server and servlet container. Effective logging is crucial for monitoring, debugging, and maintaining applications running on Tomcat.

Overview of Tomcat 7 Internal Logging with Log4j2 XML:
Tomcat 7 uses Apache Commons Logging as a facade for various logging frameworks, including Log4j2. By configuring Log4j2 with an XML file, you can manage log levels, appenders, and patterns efficiently.

Importance and Benefits:

• Enhanced Debugging: Detailed logs help identify and resolve issues quickly.
• Performance Monitoring: Logs provide insights into server performance and application behavior.
• Customizable Logging: Log4j2 allows fine-grained control over logging output, making it easier to filter and format logs.
• Resource Management: Proper logging configuration ensures efficient resource usage and cleanup.

Would you like more details on configuring Log4j2 with Tomcat 7?

Setting Up Log4j2 in Tomcat 7

Here are the steps to configure Tomcat 7 internal logging with Log4j2 using an XML configuration:

1. Remove Existing Logging Libraries:

   • Delete or move the logging.properties file from the TOMCAT_HOME/conf directory.
   • Remove jul-to-slf4j.jar and log4j-jul.jar from TOMCAT_HOME/lib.

2. Add Log4j2 Libraries:

   • Download the following Log4j2 JAR files and place them in the TOMCAT_HOME/lib directory:
     • log4j-api-2.x.jar
     • log4j-core-2.x.jar
     • log4j-web-2.x.jar
     • log4j-appserver-2.x.jar (optional, for better integration)

3. Create Log4j2 Configuration File:

   • Create a log4j2.xml file in the TOMCAT_HOME/lib directory with the following content:

     <?xml version="1.0" encoding="UTF-8"?>
     <Configuration status="WARN">
         <Appenders>
             <Console name="Console" target="SYSTEM_OUT">
                 <PatternLayout pattern="%d{ISO8601} [%t] %-5p %c{1} - %msg%n"/>
             </Console>
             <File name="File" fileName="logs/tomcat.log">
                 <PatternLayout pattern="%d{ISO8601} [%t] %-5p %c{1} - %msg%n"/>
             </File>
         </Appenders>
         <Loggers>
             <Root level="INFO">
                 <AppenderRef ref="Console"/>
                 <AppenderRef ref="File"/>
             </Root>
             <Logger name="org.apache.catalina" level="INFO" additivity="false">
                 <AppenderRef ref="Console"/>
                 <AppenderRef ref="File"/>
             </Logger>
         </Loggers>
     </Configuration>
     

4. Configure Tomcat to Use Log4j2:

   • Create a logging.properties file in the TOMCAT_HOME/conf directory with the following content:

     handlers = org.apache.logging.log4j.jul.LogManager
     .level = INFO
     

5. Set System Properties:

   • Add the following system properties to the CATALINA_OPTS in the TOMCAT_HOME/bin/catalina.sh (or catalina.bat for Windows):

     -Dlog4j.configurationFile=TOMCAT_HOME/lib/log4j2.xml
     -Djava.util.logging.manager=org.apache.logging.log4j.jul.LogManager
     

6. Restart Tomcat:

   • Restart Tomcat to apply the changes.

These steps should configure Tomcat 7 to use Log4j2 for its internal logging.

Configuring log4j2.xml

Here’s how to create and configure the log4j2.xml file for Tomcat 7 internal logging:

Step-by-Step Configuration

1. Add Log4j2 Libraries:

   • Download Log4j2 core and API jars from the Apache Log4j2 website.
   • Place the jars in the lib directory of your Tomcat installation.

2. Create log4j2.xml:

   • Place the log4j2.xml file in the conf directory of your Tomcat installation.

3. Configure Logging in log4j2.xml:

   • Here is an example configuration:

<?xml version="1.0" encoding="UTF-8"?>
<Configuration status="WARN">
    <Appenders>
        <Console name="Console" target="SYSTEM_OUT">
            <PatternLayout pattern="%d{yyyy-MM-dd HH:mm:ss} %-5p %c{1}:%L - %m%n"/>
        </Console>
        <File name="File" fileName="logs/tomcat.log">
            <PatternLayout pattern="%d{yyyy-MM-dd HH:mm:ss} %-5p %c{1}:%L - %m%n"/>
        </File>
    </Appenders>
    <Loggers>
        <Logger name="org.apache.catalina" level="INFO" additivity="false">
            <AppenderRef ref="Console"/>
            <AppenderRef ref="File"/>
        </Logger>
        <Root level="ERROR">
            <AppenderRef ref="Console"/>
            <AppenderRef ref="File"/>
        </Root>
    </Loggers>
</Configuration>

Common Configurations

1. Console Logging:
   • Logs to the console (useful for development).

<Console name="Console" target="SYSTEM_OUT">
    <PatternLayout pattern="%d{yyyy-MM-dd HH:mm:ss} %-5p %c{1}:%L - %m%n"/>
</Console>

2. File Logging:
   • Logs to a file (useful for production).

<File name="File" fileName="logs/tomcat.log">
    <PatternLayout pattern="%d{yyyy-MM-dd HH:mm:ss} %-5p %c{1}:%L - %m%n"/>
</File>

3. Logger Configuration:
   • Configures logging levels and appenders for specific packages.

<Logger name="org.apache.catalina" level="INFO" additivity="false">
    <AppenderRef ref="Console"/>
    <AppenderRef ref="File"/>
</Logger>

4. Root Logger:
   • Configures the root logger, which applies to all loggers unless overridden.

<Root level="ERROR">
    <AppenderRef ref="Console"/>
    <AppenderRef ref="File"/>
</Root>

Final Steps

1. Update catalina.properties:
   • Add the following line to catalina.properties to specify the Log4j2 configuration file:

log4j.configurationFile=${catalina.base}/conf/log4j2.xml

2. Remove Default Logging:

   • Remove or comment out the default logging configuration in logging.properties.

3. Restart Tomcat:

   • Restart Tomcat to apply the new logging configuration.

Integrating Log4j2 with Tomcat 7

Here’s a concise guide to integrate Log4j2 with Tomcat 7 for internal logging:

1. Remove JULI: Delete or rename tomcat-juli.jar and tomcat-juli-adapters.jar from TOMCAT_HOME/lib.

2. Add Log4j2 Jars: Download Log4j2 core and API jars, and place them in TOMCAT_HOME/lib.

3. Create Log4j2 Configuration: Create a log4j2.xml configuration file and place it in TOMCAT_HOME/lib. Example configuration:

   <Configuration status="WARN">
       <Appenders>
           <Console name="Console" target="SYSTEM_OUT">
               <PatternLayout pattern="%d{ISO8601} [%t] %-5p %c{1}:%L - %m%n"/>
           </Console>
       </Appenders>
       <Loggers>
           <Root level="INFO">
               <AppenderRef ref="Console"/>
           </Root>
       </Loggers>
   </Configuration>
   

4. Configure Logging Properties: Edit TOMCAT_HOME/conf/logging.properties to include:

   handlers = org.apache.logging.log4j.jul.LogManager
   

5. Set System Properties: Add the following JVM options to TOMCAT_HOME/bin/setenv.sh or setenv.bat:

   -Dlog4j.configurationFile=TOMCAT_HOME/lib/log4j2.xml
   -Djava.util.logging.manager=org.apache.logging.log4j.jul.LogManager
   

6. Restart Tomcat: Restart Tomcat to apply the changes.

This setup ensures that all internal logs from Tomcat are captured correctly using Log4j2.

Testing and Troubleshooting

Methods for Testing Tomcat 7 Internal Logging with Log4j2 XML Setup

1. Setup Log4j2 Configuration:

   • Place log4j2.xml in WEB-INF/classes or lib directory.
   • Ensure the configuration file is correctly named log4j2.xml.

2. Modify Tomcat Configuration:

   • Edit catalina.properties to include Log4j2 JARs in the classpath:

     common.loader="${catalina.base}/lib/*.jar,${catalina.base}/lib/log4j-core-2.x.jar,${catalina.base}/lib/log4j-api-2.x.jar"
     

   • Remove or comment out the default java.util.logging configuration.

3. Test Logging:

   • Deploy a simple web application that generates log messages.
   • Check the log output in the configured log files or console.

Troubleshooting Common Issues

1. No Logs Output:

   • Verify log4j2.xml is correctly placed and named.
   • Check for missing Log4j2 JARs in the classpath.

2. Configuration Errors:

   • Increase verbosity by setting <StatusLogger> level to DEBUG in log4j2.xml:

     <Configuration status="DEBUG">
     

3. ClassNotFoundException:

   • Ensure all required Log4j2 dependencies are included in lib directory.

4. Incorrect Log Levels:

   • Confirm log levels are correctly set in log4j2.xml.

Configuring Tomcat 7 for Internal Logging with Log4j2 XML

To configure Tomcat 7 for internal logging using Log4j2 XML, you need to create a `log4j2.xml` file in the `WEB-INF/classes` or `lib` directory and set up the necessary system properties. This involves modifying the `catalina.properties` file to include Log4j2 JARs in the classpath and removing or commenting out the default Java Util Logging configuration.

Key Points

• Create a `log4j2.xml` file with the correct configuration for internal logging.
• Set up system properties by adding JVM options to the `setenv.sh` or `setenv.bat` file, including the Log4j2 configuration file and the Java Util Logging manager.
• Restart Tomcat to apply the changes.
• Test logging by deploying a simple web application that generates log messages and checking the output in the configured log files or console.

Common Issues

Common issues include no logs output, configuration errors, ClassNotFoundException, and incorrect log levels. Troubleshooting involves verifying the `log4j2.xml` file, checking for missing Log4j2 JARs, increasing verbosity by setting the StatusLogger level to DEBUG, ensuring all required dependencies are included in the lib directory, and confirming log levels are correctly set.

Benefits

This setup ensures that all internal logs from Tomcat are captured correctly using Log4j2, improving logging efficiency.