Jenkins/Hudson CLI API to modify the node labels using Groovy

Question

Does anyone know how to modify the Jenkins/Hudson node labels in a non-manually way? I mean, thorough an API like the CLI API that this tool offers (without restarting Jenkins/H

Answer 1

Note: the other answers are a bit old, so it could be that the API has appeared since then.

Node labels are accessed in the API as a single string, just like in the Configure screen.

To read and write labels: Node.getLabelString() and Node.setLabelString(String).

Note that you can get the effective labels as well via: Node.getAssignedLabels(), which returns a Collection of LabelAtom that includes dynamically computed labels such as the 'self-label' (representing the node name itself).

Last, these methods on the Node class are directly accessible from the slave objects also, e.g. as a System Groovy Script:

hudson = hudson.model.Hudson.instance
hudson.slaves.findAll { it.nodeName.equals("slave4") }.each { slave -> 
  print "Slave  $slave.nodeName : Labels: $slave.labelString"
  slave.labelString = slave.labelString + " " + "offline"
  println "   --> New labels: $slave.labelString"
}
hudson.save()

Answer 2

I've found a way to do this using the Groovy Postbuild Plugin.

I have a Jenkins job that takes a few parameters (NodeToUpdate, LabelName, DesiredState) and executes this content in the Groovy Postbuild Plugin:

nodeName = manager.envVars['NodeToUpdate']
labelName = manager.envVars['LabelName']
set = manager.envVars['DesiredState']

for (node in jenkins.model.Jenkins.instance.nodes) {
    if (node.getNodeName().equals(nodeName)) {
        manager.listener.logger.println("Found node to update: " + nodeName)
        oldLabelString = node.getLabelString()
        if (set.equals('true')) {
            if (!oldLabelString.contains(labelName)) {
                manager.listener.logger.println("Adding label '" + labelName     + "' from node " + nodeName);
                newLabelString = oldLabelString + " " + labelName
                node.setLabelString(newLabelString)
                node.save()
            } else {
                manager.listener.logger.println("Label '" + labelName + "' already exists on node " + nodeName)
            }
        }
        else {
            if (oldLabelString.contains(labelName)) {
                manager.listener.logger.println("Removing label '" + labelName + "' from node " + nodeName)
                newLabelString = oldLabelString.replaceAll(labelName, "")
                node.setLabelString(newLabelString)
                node.save()
            } else {
                manager.listener.logger.println("Label '" + labelName + "' doesn't exist on node " + nodeName)
            }
        }
    }
}

Answer 3

I've not seen a way yet to change the slave label either.

I've taken to editing the main config.xml file and issuing a reload from the CLI.

This has it's own problems though - any jobs currently running are lost until the next jenkins restart - see https://issues.jenkins-ci.org/browse/JENKINS-3265