QuickKnol: Integrating Logback with Scala

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Logback is the successor of Log4j and is one of the better logging frameworks around. In this post, we would quickly see how to set it up on a Scala project and how to start using it.

The relevant dependency to be included in your build.sbt is

libraryDependencies += “ch.qos.logback” % “logback-classic” % “1.0.1”

Once, you have this set, next you have to get a logback.xml file in your classpath. If you are using a sbt generated project, the best place to put it would be /src/main/resources and for your tests, you could put a logback-test.xml in /src/test/resources

A sample, logback.xml file would look like this

<configuration>
	<appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender">
		<encoder>
			<pattern>%d{HH:mm:ss.SSS} TKD [%thread] %-5level %logger{36} - %msg%n
			</pattern>
		</encoder>
	</appender>

	<root level="debug">
		<appender-ref ref="STDOUT" />
	</root>
</configuration>

Once these are done, next let us just test it out. Following is a small Scala program to check

package com.knoldus.logme
import org.slf4j.LoggerFactory
import ch.qos.logback.core.util.StatusPrinter
import ch.qos.logback.classic.LoggerContext

object LogTester extends App{
  def logger = LoggerFactory.getLogger("KDURLFilter")
  StatusPrinter.print((LoggerFactory.getILoggerFactory).asInstanceOf[LoggerContext])
  logger.info("vikas")
}

and the output

13:05:43,469 |-INFO in ch.qos.logback.classic.LoggerContext[default] - Could NOT find resource [logback.groovy]
13:05:43,470 |-INFO in ch.qos.logback.classic.LoggerContext[default] - Could NOT find resource [logback-test.xml]
13:05:43,470 |-INFO in ch.qos.logback.classic.LoggerContext[default] - Found resource [logback.xml] at [file:/home/vikas/dev/12kd/LogbackWAssembly/bin/logback.xml]
13:05:43,789 |-INFO in ch.qos.logback.classic.joran.action.ConfigurationAction - debug attribute not set
13:05:43,810 |-INFO in ch.qos.logback.core.joran.action.AppenderAction - About to instantiate appender of type [ch.qos.logback.core.ConsoleAppender]
13:05:43,818 |-INFO in ch.qos.logback.core.joran.action.AppenderAction - Naming appender as [STDOUT]
13:05:43,975 |-INFO in ch.qos.logback.core.joran.action.NestedComplexPropertyIA - Assuming default type [ch.qos.logback.classic.encoder.PatternLayoutEncoder] for [encoder] property
13:05:44,048 |-INFO in ch.qos.logback.classic.joran.action.RootLoggerAction - Setting level of ROOT logger to DEBUG
13:05:44,048 |-INFO in ch.qos.logback.core.joran.action.AppenderRefAction - Attaching appender named [STDOUT] to Logger[ROOT]
13:05:44,049 |-INFO in ch.qos.logback.classic.joran.action.ConfigurationAction - End of configuration.
13:05:44,051 |-INFO in ch.qos.logback.classic.joran.JoranConfigurator@1e6db24 - Registering current configuration as safe fallback point

13:05:44.057 TKD [main] INFO  KDURLFilter - vikas

Entire code for this sample is present on the Knoldus github site

Happy Logging.