Configuring logging in Grails is not as simple one would think. Grails uses Log4J as its logging framework. Log4J configuration is stored in the log4j.properties file. Grails Logging
log5j - Google Code
The Simple Logging Facade for Java (SLF4J) serves as a simple facade or abstraction for various logging frameworks (e.g. java.util.logging, logback, log4j) allowing the end user to plug in the desired logging framework at deployment time. Before you start using SLF4J, we highly recommend that you read the two-page SLF4J user manual. Note that SLF4J-enabling your library implies the addition of only a single mandatory dependency, namely slf4j-api.jar. If no binding is found on the class path, then SLF4J will default to a no-operation implementation. In case you wish to migrate your Java source files to SLF4J, consider our migrator tool which can migrate your project to use the SLF4J API in just a few minutes.
This tutorial explains how to set up log4j with email, files and stdout. It compares XML to properties configuration files, shows how to change LogLevels for a running application. Furthermore, we explain best practices on logging and exception handling. Log4j tutorial with Tomcat examples
Annotated logging interceptor with Spring AOP