separate info, error logs using logback grails

// File: grails-app/conf/logback-grails.groovy
import grails.util.BuildSettings
import grails.util.Environment

import org.springframework.boot.ApplicationPid

import java.nio.charset.Charset

// Log information about the configuration.
statusListener(OnConsoleStatusListener)

// Get PID for Grails application.
// We use it in the logging output.
if (!System.getProperty("PID")) {
    System.setProperty("PID", (new ApplicationPid()).toString())
}

conversionRule 'clr', org.springframework.boot.logging.logback.ColorConverter
conversionRule 'wex', org.springframework.boot.logging.logback.WhitespaceThrowableProxyConverter

// See http://logback.qos.ch/manual/groovy.html for details on configuration
appender('STDOUT', ConsoleAppender) {
    encoder(PatternLayoutEncoder) {
        charset = Charset.forName('UTF-8')
        pattern =
                '%clr(%d{yyyy-MM-dd HH:mm:ss.SSS}){faint} ' + // Date
                        '%clr(%5p) ' + // Log level
                        '%clr(%property{PID}){magenta} ' + // PID
                        '%clr(---){faint} %clr([%15.15t]){faint} ' + // Thread
                        '%clr(%-40.40logger{39}){cyan} %clr(:){faint} ' + // Logger
                        '%m%n%wex' // Message
    }
}

root(WARN, ['STDOUT'])

if(Environment.current == Environment.DEVELOPMENT) {
    root(INFO, ['STDOUT'])

    def targetDir = BuildSettings.TARGET_DIR
    if(targetDir) {

        appender("FULL_STACKTRACE", FileAppender) {

            file = "${targetDir}/stacktrace.log"
            append = true
            encoder(PatternLayoutEncoder) {
                pattern = "%level %logger - %msg%n"
            }
        }
        logger("StackTrace", ERROR, ['FULL_STACKTRACE'], false )
    }
}