According to the documentation for Google App Engine for Java:
The App Engine Java SDK includes a template logging.properties file, in the appengine-java-sdk/config/user/ directory. To use it, copy the file to your WEB-INF/classes directory (or elsewhere in the WAR), then the system property java.util.logging.config.file to "WEB-INF/classes/logging.properties" (or whichever path you choose, relative to the application root). You can set system properties in the appengine-web.xml file, as follows:
<appengine-web-app xmlns="http://appengine.google.com/ns/1.0">
...
<system-properties>
<property name="java.util.logging.config.file" value="WEB-INF/classes/logging.properties" />
</system-properties>
</appengine-web-app>
The Google Plugin for Eclipse new project wizard creates these logging configuration files for you, and copies them to WEB-INF/classes/ automatically. For java.util.logging, you must set the system property to use this file.
If your write to standard out or standard error, that will automatically get logged as INFO or WARNING.
So, why do you need to use a logging.properties
file?
Does this give you some additional control over your logging?