4.7.2. Logging Configuration Internals

Since7.2

This section explains internal working of the Logback configuration, which can be useful for troubleshooting.

The platform provides the LogbackConfigurator class that hooks into standard Logback initialization procedure as an implementation of Configurator. This configurator performs the following steps to find a source of the configuration:

  • Looks for logback.xml in the application home (i.e. a directory specified by the app.home system property).

  • If not found, looks for app-logback.xml on classpath root.

  • If nothing found, performs the basic configuration: output to console with WARN threshold.

Keep in mind, that this procedure comes into play only if there is no logback.xml on the classpath root.

The setupTomcat Gradle task creates logback.xml in deploy/app_home directory, so the initialization procedure explained above takes it on the first step. As a result, any development environment gets a default logback config writing logs to deploy/app_home/logs directory.

The deploy Gradle task copies etc/logback.xml project file (if it exists) to deploy/app_home, so developers can create and customize the logback config in the project and it will be used automatically in development Tomcat.

The buildWar and buildUberJar tasks can create app-logback.xml in classpath root (which is /WEB-INF/classes for WAR and / for UberJAR) from one of the following source files:

  • From logbackConfigurationFile task parameter if it is specified.

  • From logback.xml in cuba-gradle-plugin if useDefaultLogbackConfiguration task parameter is set to true (which is default).

If logbackConfigurationFile is not specified and useDefaultLogbackConfiguration is set to false, no any logback config is created in the archive.

Due to LogbackConfigurator initialization procedure and provided that there is no logback.xml in the classpath root, the configuration embedded into WAR/UberJAR can be overridden by logback.xml file in the application home directory. It enables customization of logging in production environment without rebuilding WAR/UberJAR.