A Quick Overview

For logging, we use the slf4j facade, usually hooked up to a log4j implementation.

Tests have debug logging across the board, included by default from usage/test-support

Launcher (and all) define a log4j.properties which logs at INFO level with a few selected categories at DEBUG (debug output goes only to a file, ./brooklyn.log).

Some categories are quite useful, as you'll see in the log4j.properties files in the project:

  • brooklyn
  • brooklyn.SSH
  • org.jclouds



If you've not inherited brooklyn-launcher (or brooklyn-all) you'll need a log4j.properties (or log4j.xml, which will dominate). There are plenty of other valid reasons for wanting to supply your own logging as well.

A good starting point is the configuration file in launcher.

Once you've tweaked this, place it in your classpath, or specify -Dlog4j.configuration=/path/to/your/log4j.properties. For more information see logging.apache.org/log4j.


If you've not inherited brooklyn-launcher (or brooklyn-all) you may not have an SLF4J implementation project on your classpath (you'll see some SLF4J complaints at runtime). Adding a dependency on an implementation, such as log4j12, should resolve the problem:


As of this writing we use 1.5.11 for the version, as per the root pom. The optional line means the dependency should not be passed to any projects which depend on your project; you can remove it to force the import your logging implementation choice. (You can of course use a differing slf4j-compliant logger, such as java.util.logging or ch.qos.logback.)


  • SLF4J version >= 1.6 is not compatible with 1.5.x and breaks certain things (such as the web console written in Grails).

  • The webapp can clobber logging settings in strange ways; setting grails, grails.app, and grails.app.brooklyn to INFO seems to help.

  • Logging for tests isn't picked up correctly in some environments (some Eclipse flavours). The root cause seems to be a rogue log4j.properties included in the groovy-all OSGi bundle bsf.jar which sets a FATAL threshhold. To resolve this add an explicit project dependency on test-support, or create your own log4j.properties file.