logging.adoc

Logging and Diagnostics

Standard logging

Jenkins uses java.util.logging for logging, including in Remoting and Swarm. By default, java.util.logging uses the configuration from ${JAVA_HOME}/jre/lib/logging.properties. This is typically something like the following:

handlers = java.util.logging.ConsoleHandler
.level = INFO
java.util.logging.ConsoleHandler.level = INFO
java.util.logging.ConsoleHandler.formatter = java.util.logging.SimpleFormatter

The default handler, ConsoleHandler, sends INFO-level log records to System.err, using SimpleFormatter.

Configuration

To get more detailed logs from the Swarm client, create a custom logging.properties file and pass it in via the java.util.logging.config.file property. This repository contains a sample verbose logging.properties file. For example:

$ java -Djava.util.logging.config.file='logging.properties' -jar swarm-client.jar

For more information about the property file format, see the Oracle documentation and this guide.