In our Jenkins init script, we run the following to set loggers to only get messages of the WARNING level from a certain Java class printed to the log:

// Part of our init script
import java.util.logging.Level
import java.util.logging.Logger

Logger.getLogger(<class_name>).setLevel(Level.WARNING);

A problem is that this doesn't seem to work for some classes. Messages of the level INFO from these classes still appear in the log, and under <jenkins_master>/log/all the loggers for the affected classes don't show up.

Loggers that work, and show up up under log/all:

• com.amazon.jenkins.ec2fleet.CloudNanny
• hudson.model.Run
• hudson.plugins.promoted_builds.integrations.jobdsl.PromotionsExtensionPoint
• javaposse.jobdsl.plugin.JenkinsJobManagement
• jp.ikedam.jenkins.plugins.groovy_label_assignment.GroovyLabelAssignmentProperty
• org.jenkinsci.plugins.ParameterizedRemoteTrigger.utils.DropCachePeriodicWork

Loggers that don't work, and don't show up under log/all:

• com.amazon.jenkins.ec2fleet.EC2FleetCloud
• org.jenkinsci.plugins.p4.tasks.CheckoutTask