Liferay 6 and Sentry

Introduction

Sentry [1] is a great tool for error tracking and Liferay [2] is a very popular portal software that we deploy for out customer as part of our main product.

Log4j configuration with Liferay

As stated in [3], custom log4j configuration is done adding these files:

• portal-log4j-ext.xml
• log4j.dtd

to folder: tomcat-[version]/webapps/ROOT/WEB-INF/classes/META-INF where [version] is something like 7.0.23 and depends on the concrete Liferay version you are working with.

The portal-log4j-ext.xml overrides the file portal-log4j.xml which can be found inside portal-impl.jar (in webapps/ROOT/WEB-INF/lib). You can get a copy from here [4]. The companion file log4j.dtd can be found here [5].

Get Sentry Java Client (raven-java)

To log any errors in our Liferay instance to Sentry, we need a Sentry Java Client which works together with log4j (a Log4j appender) and can be downloaded from here [7].

Although Liferay already includes log4j 1.2.x we choose the jar that includes all dependencies (for a reason I explain below):

Download the file raven-log4j-[version]-jar-with-dependencies.jar where [version] is currently: 1.0-SNAPSHOT. 

Configure Liferay to log to Sentry

This is done it two steps:

1. Copy the downloaded raven-log4j JAR to tomcat-/lib
2. Customize portal-log4j-ext.xml

Copy raven-log4j file

Copy the downloaded raven-[version]-jar-with-dependencies.jar to tomcat-[version]/lib.
Although all the java dependencies should normally live together with the web application and the downloaded file contains log4j 1.2.x, we have chosen this approach for the following reasons:

• Then specific log4j appender and Sentry java client (raven-java) will be available for other deployed web applications. Take into account that in Liferay deployment each extra portlet is considered a separate web application with its own J2EE application context. Each of them will have to be configured individually to log to Sentry.
• The log4j version included in raven-log4j-[version]-jar-with-dependencies.jar has the same major and minor version (1.2), i.e. the Sentry log appender (SentryAppender and AsyncSentryAppender) should be 100% compatible. Special caution should be given when using other versions.
• The tomcat/lib contains class libraries (JAR) which are shared between all of the deployed web applications (WAR). But (!) the J2EE classloader magic avoids calls from a shared class library back to a web application class. In this case, it doesn't happen.
• The web application classes and class libraries have preference when searching for a class

Customize portal-log4j-ext.xml

Following this example [6] where Nuxeo is configured for Sentry, we have to add an appender and activate it in portal-log4j-ext.xml, like this:

 <?xml version="1.0"?>  
 <!DOCTYPE log4j:configuration SYSTEM "log4j.dtd">  
 <log4j:configuration xmlns:log4j="http://jakarta.apache.org/log4j/">  
   <appender class="org.apache.log4j.ConsoleAppender" name="CONSOLE">  
     <layout class="org.apache.log4j.PatternLayout">  
       <param name="ConversionPattern" value="%d{ABSOLUTE} %-5p [%c{1}:%L] %m%n" />  
     </layout>  
   </appender>  
   <appender class="org.apache.log4j.rolling.RollingFileAppender" name="FILE">  
     <rollingpolicy class="org.apache.log4j.rolling.TimeBasedRollingPolicy">  
       <param name="FileNamePattern" value="@liferay.home@/logs/liferay.%d{yyyy-MM-dd}.log" />  
     </rollingpolicy>  
     <layout class="org.apache.log4j.PatternLayout">  
       <param name="ConversionPattern" value="%d{ABSOLUTE} %-5p [%c{1}:%L] %m%n" />  
     </layout>  
   </appender>  
   <appender class="net.kencochrane.raven.log4j.SentryAppender" name="Sentry">  
     <param name="dsn" value="http://[two hashes separared by a colon]@log.tangrambpm.es/5" />  
     <filter class="org.apache.log4j.varia.LevelRangeFilter">  
       <param name="levelMin" value="INFO" />  
     </filter>  
   </appender>  
   <category name="com.ecyrd.jspwiki">  
     <priority value="ERROR">  
   </priority></category>  
 ...  
   <root>  
     <priority value="INFO">  
     <appender-ref ref="CONSOLE">  
     <appender-ref ref="FILE">  
     <appender-ref ref="Sentry">  
   </appender-ref></appender-ref></appender-ref></priority></root>  
 </log4j:configuration>  

After theses steps and a Liferay restart you should be done.

References

• [1] Sentry doc main page: http://sentry.readthedocs.org/
• [2] Liferay main product page: https://www.liferay.com/
• [3] Liferay log4j configuration wiki: http://www.liferay.com/es/community/wiki/-/wiki/Main/How+to+configure+the+logs+in+Liferay/
• [4] Liferay Log4j configuration file portal-log4j.xml: https://github.com/liferay/liferay-portal/blob/6.1.x/portal-impl/src/META-INF/portal-log4j.xml
• [5] Liferay Log4j DTD file for Liferay: https://github.com/liferay/liferay-portal/blob/6.1.x/portal-impl/src/META-INF/log4j.dtd 
• [6] Nuxeo Log4j configuration example for Sentry: http://answers.nuxeo.com/questions/5914/how-to-use-third-party-log4j-appenders-in-nuxeo-tomcat-distribution
• [7] raven-java downloads: https://github.com/kencochrane/raven-java/downloads
• [8] raven-log4j  Maven repository entry at mvnrepository.com: http://mvnrepository.com/artifact/net.kencochrane.raven/raven-log4j/4.1.2