Grails Goodness: Add a DailyRollingFileAppender to Grails Logging

In Grails we can add new Log4J appenders to our configuration. We must add the new appender definition in the log4j closure in conf/Config.groovy. We define new appenders with the appenders() method. We pass in a closure where we define our appenders. The name of the appender is an identifier we can use when we want to define the log level and packages that need to be logged by the appender.

In the following sample configuration we create a DailyRollingFileAppender so each day a new log file is created and old log files are renamed with the date in the filename. Then we use the root() method to pass a closure telling we want to log all messages at level INFO to the appender.

// File: conf/Config.groovy
import org.apache.log4j.DailyRollingFileAppender

log4j = {
    appenders {
        appender new DailyRollingFileAppender(
            name: 'dailyAppender',
            datePattern: "'.'yyyy-MM-dd",  // See the API for all patterns.
            fileName: "logs/${appName}.log",
            layout: pattern(conversionPattern:'%d [%t] %-5p %c{2} %x - %m%n')        
        )
    }
    
    root {
        info 'dailyAppender'
    }    
}